Introduction
Heart failure (HF) is extremely prevalent and has a considerable impact on mortality
and quality of life.
1
It affects nearly 1-3% of the adult population in developed countries, exponentially
increasing with age and affecting more than 10% of the population over 70 years. Given
the increase in the average life expectancy, better diagnostic methods and increased
comorbidities, a greater prevalence of heart failure is expected.
2
It is a clinical syndrome characterized by classic symptoms (such as fatigue, dyspnea)
that may be accompanied by clinical signs (elevated jugular pressure, pulmonary crackles
and peripheral edema). It is caused by structural and/or functional cardiac abnormalities,
resulting in reduced cardiac output and/or elevated intracardiac pressures at rest
or during stress.
3
The main terminology used to describe HF is based on the measurement of the left ventricular
ejection fraction (EF), differentiating patients with reduced <40% (HFrEF), mid-range
40-49% (HFmrEF) and preserved ≥50% (HFpEF) ejection fraction. This classification
is important due to different underlying etiologies, pathophysiology, available treatment
and its respective response.
3
HFpEF accounts for about half of the cases of HF in developed countries.
4
Its pathophysiology is complex, heterogeneous and still poorly understood. The wide
variety of phenotypes resulting from the several pathophysiological mechanisms, comorbidities
and dominant clinical characteristics, make diagnosis and treatment extremely challenging.
4
Unlike HFrEF, no treatment has unquestionably shown a reduction of morbidity or mortality
in patients with HFpEF or HFmrEF. Several clinical trials evaluating drugs proven
to be effective in HFrEF have failed to demonstrate prognostic benefits in these patients.
4
Current recommendations are based on symptom relief, screening, and treatment of comorbidities.
3
New therapies are presently under research, especially directed at the pathophysiological
mechanisms of the disease.
5
This review addresses the pathophysiology of HFpEF and summarizes the studies that
have been carried out regarding treatment, including failures, hopes and future prospects.
For this article, we carried out a systematic search in three databases: Medline -
Pubmed, ISI Web of knowledge and Scopus, using the following keywords in English and
Portuguese: "Heart failure AND preserved ejection fraction", "Heart failure AND preserved
ejection fraction AND physiopathology” and “Heart failure AND preserved ejection fraction
AND treatment". The study was conducted between January and March of 2019. Prospective
and retrospective studies were included. Clinical cases, abstracts presented at conferences
(not published as articles) and studies with a sample size of less than 10 patients
were excluded. The eligibility of each study was independently assessed by three researchers.
The divergent opinions regarding the relevance of the articles were resolved by consensus
among the authors.
Pathophysiology
The pathophysiology of the disease is complex and remains insufficiently understood.
It is known that these patients are generally older, females and have multiple cardiovascular
comorbidities, such as hypertension, atrial fibrillation (AF), coronary artery disease
(CAD), pulmonary hypertension (PH), and non-cardiovascular diseases such as diabetes,
chronic kidney disease (CKD), anemia, chronic obstructive pulmonary disease (COPD),
among others. They also have a higher percentage of non-cardiovascular pathologies,
with a great impact on morbidity and mortality, and a lower incidence of acute myocardial
infarction (AMI) as well as sudden cardiac death or death from HF.
6
Historically, HFpEF was exclusively associated with diastolic dysfunction, opposed
to HFrEF, which was associated with systolic dysfunction. It is currently known that
this is not such a clear-cut matter, as both types of HF may also show systolic and/or
diastolic dysfunction. Different mechanisms are involved in HFpEF. This is thought
to result from a complex variety of cardiac, vascular and systemic dysfunctions, with
the contribution of several comorbidities.
4
(Figure 1)
Figure 1
Pathophysiology of HFpEF - possible mechanisms involved. AF: atrial fibrillation;
CAD: coronary artery disease; CKD: chronic kidney disease; COPD: chronic obstructive
pulmonary disease; HFpEF: heart failure with preserved ejection fraction; HT: arterial
hypertension; NO-cGMP-PKG: nitric oxide, reduced cyclic guanosine monophosphate and
protein kinase G; PH: pulmonary hypertension; RAAS: renin-angiotensin-aldosterone
system; RV: right ventricle.
Diastolic dysfunction is usually present and results from structural changes (cardiac
fibrosis, hypertrophy and remodeling ), microvascular dysfunction and metabolic abnormalities,
with increased stiffness and decreased cardiac compliance. This leads not only to
an increase in LV filling pressures, but also to structural and functional changes
at the atrial, pulmonary and right ventricular levels, due to a rise in upstream pressures.
The systolic reserve is also affected, mainly due to changes in the ventricular-vascular
coupling ratio.
4
Atrial changes, with dilatation and remodeling, favor the appearance of AF. Pulmonary
hypertension, present in 53-83% of the cases and associated with a worse prognosis,
also seems to contribute to the disease progression.
7
The onset of right ventricular dysfunction, with systemic venous congestion, also
predicts worse results, associated with edema, malabsorption, congestive hepatopathy,
cardiorenal syndrome and cachexia.
Another mechanism involved is chronotropic incompetence, with inadequate heart rate
(HR) variations, probably due to autonomic nervous system dysfunctions.
4
Electrical and/or mechanical, systolic and diastolic asynchronies were also observed
in some patients.
7
Its magnitude is related to the extent of diastolic dysfunction and exercise capacity.
4
Many of these changes are not apparent, nor do they entail any impairment at rest,
with functional reserve limitations being evident only under stress.
Neurohormonal alterations, such as autonomic dysfunction and activation of the renin-angiotensin-aldosterone
system (RAAS) are also important mechanisms involved.
4
At the vascular level, we can observe endothelial dysfunction, systemic inflammation,
increased vessel stiffness and impaired vasodilation. A potential mechanism could
be the deregulation of the NO-sGC-cGMP-PKG signaling pathway (nitric oxide, soluble
guanylate cyclase, reduced cyclic guanosine monophosphate and protein kinase G), which
is responsible for smooth muscle relaxation, cardiac protection, gene transcription,
endothelial permeability and platelet inhibition.
5
At the peripheral level, musculoskeletal changes seem to contribute to aerobic capacity
reduction, with less exercise tolerance.
Both the age and the several comorbidities intensify these mechanisms and contribute
to disease progression. The interaction between the various pathophysiological factors
and comorbidities and the relative dominance of each of them makes this pathology
complex and heterogeneous, making its diagnosis and treatment extremely difficult.
A subgroup analysis with certain phenotypes can facilitate this process by allowing
a more particular and direct approach.
4
Diagnosis
The diagnosis of HFpEF is more challenging than the diagnosis of HFrEF. There have
been several proposed classifications and inclusion criteria in the conducted studies,
contributing to the enormous heterogeneity of patients assessed in the clinical trials.
1
The current guidelines proposed by the European Society of Cardiology suggest the
existence of 3 diagnostic criteria: symptoms and signs of HF, LVEF ≥ 50%, elevated
levels of natriuretic peptides and relevant structural heart disease and/or diastolic
dysfunction.
3
Notwithstanding these recommendations, and given the clinical heterogeneity, absence
of pathognomonic criteria and the multiplicity of differential diagnoses, there are
several challenges and uncertainties to be faced.
5
Treatment
Unlike HFrEF, no treatment has yet shown a reduction in morbidity or mortality. Therefore,
current recommendations are based on symptom relief with diuretics, screening and
treatment of comorbidities.
3
Diuretics are recommended in case of congestion, for symptom relief, regardless of
the LVEF.
3
They are widely used, especially loop diuretics, even though there are no specific
recommendations concerning which diuretic therapy should be followed.
8
Several clinical trials have studied the effect of drugs proven to be effective in
HFrEF for the treatment of patients with HFpEF (Table 1-A).
Table 1
A) Main studies performed in patients with HFpEF using effective drugs in the treatment
of the HFrEF; B) New drugs and new approaches in HFpEF
A
Clinical Trial
Year
Intervention
Patients, n
Major inclusion criteria
Mean follow-up
Main conclusions
Beta Blockers
SENIORS
9
2005
Nebivolol vs. placebo
2128
≥70 years, mean LVEF of 36%, 35% with LVEF > 35%, 68% CAD
1,8 years
Well tolerated and effective in reducing mortality and CV hospitalization (HR 0.86,
95%CI: 0.74-0.99; p = 0.039)
ACEI/ARB
CHARM Preserved
13
2003
Candesartan vs. placebo
3023
>18 years, LVEF > 40%, NYHA II-IV
3 years
Tends towards a reduction in CV mortality and HF hospitalization (unadjusted HR 0.89
95%CI: 0.77-1.03, p = 0.118; adjusted 0.86 [0.74-1·0], p = 0.051)
PEP-CHF
14
2006
Perindopril vs. placebo
850
≥70 years, HF under diuretic therapy, diastolic dysfunction, without systolic or valvular
dysfunction
2,1 years
No difference in mortality or CV hospitalization (HR 0.92 95%CI: 0.70-1.21, p = 0.545).
Some improvements in symptoms, exercise capacity and HF hospitalization in the first
year of follow-up (younger patients with AMI or hypertension)
I-PRESERVE
12
2008
Irbesartan vs. placebo
4128
>60 years, LVEF > 45%, NYHA II-IV
4.1 years
No difference in mortality or CV hospitalization (HR 95%CI: 0.86-1.05, p = 0.35)
Enalapril
15
2010
Enalapril vs. placebo
71
70 ± 1 years (80% women), LVEF ≥ 50%, Compensated HF and controlled Hypertension
1 year
No impact on exercise capacity (p = 0.99), aortic distensibility (p = 0.93), ventricular
volume and mass (p = 1) or quality of life (p = 0.07)
MRA
Aldo -DHF
16
2013
Spironolactone vs. placebo
422
≥50 years, LVEF ≥ 50%, NYHA II-III, diastolic dysfunction
1 year
Improved diastolic function (E/e' p < 0.001, ventricular remodeling p = 0.09 and neurohormonal
activation; p = 0.03). Did not improve exercise capacity, symptoms or quality of life
(p = 0.03)
TOPCAT
17
2014
Spironolactone vs. placebo
3445
≥50 years, LVEF ≥ 45%, Symptomatic HF, hospitalization within last 12 months or elevated
natriuretic peptides
3.3 years
No reduction in CV mortality, cardiac arrest or HF hospitalization (HR 0.89, 95%CI:
0.77-1.04, p = 0.14). Some benefit in terms of natriuretic peptide levels
ARNI
PARAMOUNT
19
2012
Sacubitril/valsartan vs. valsartan
301
LVEF ≥ 45%, NYHA II-III and NT-proBNP > 400 pg/ml
12 and 36 weeks
Reduction in NT-proBNP at 12 weeks (HR 0.77, 95%CI: 0.64-0.92, p = 0.005); LA volume
reduction (p = 0.003) and NYHA class improvement (p = 0.05) at 36 weeks
PARAGON
20
2019*
Sacubitril/valsartan vs. valsartan
4300
LVEF ≥ 45%, NYHA II-IV, elevated natriuretic peptides and evidence of structural heart
disease
>2 years
Evaluation of CV mortality and HF hospitalizations
Ivabradine
If- ChannelInhibitors
22
2013
Ivabradine vs. placebo
61
LVEF ≥ 50%, diastolic dysfunction, NYHA II-III, sinus rhythm, HR ≥ 60 bpm, exercise
capacity <80% for age and gender
7 days
Increased exercise capacity (p = 0.001), with improvement in hemodynamic status during
the exercise (p = 0.004); improved LV filling pressure (p = 0.02)
EDIFY
21
2017
Ivabradine vs. placebo
179
LVEF ≥ 45%, NYHA II-III, sinus rhythm, HR ≥70 bpm, NT-proBNP ≥ 220 pg/mL(BNP ≥ 80 pg/mL
8 months
No improvement in diastolic function (HR 1.4 90%CI: 0.3-2.5, p = 0.135), exercise
capacity (p = 0.882) or NT-proBNP level (HR 1.01, 90%CI: -0.86-1.19; p = 0.882)
Digoxin
DIG PEF
23
2006
Digoxin vs. placebo
988
LVEF > 40% (mean 53%), sinus rhythm
3.1 years
No effect on natural history endpoints such as mortality and hospitalizations (HR
0.82; 95%CI: 0.63-1.07; p = 0.136)
Nitrates and Nitrites
NEAT HFpEF
24
2015
Isosorbide mononitrate vs. placebo
110
≥50 years, LVEF ≥ 50%, evidence of HF
6 weeks
No effect on quality of life (p = 0.37) or NT-proBNP levels (p = 0.22); Reduction
in daily activity level (-381 95%CI -780-17, p = 0.06) and increased symptoms of HF
Inorganic nitrate on exercise capacity
25
2015
NO3-rich beetroot juice vs. placebo (single dose)
17
Symptomatic HF, LVEF > 50%
12 days
Increased exercise capacity (p = 0.04) (reduction in systemic vascular resistance,
increased cardiac output and increased oxygen delivery)
Sildenafil
RELAX
26
2013
Sildenafil vs. placebo
216
LVEF ≥ 50%, NYHA II-IV, NT-proBNP > 400 pg/mL, Peak VO2 < 60%, or elevated LV filling pressures
24 weeks
No effect on exercise capacity (p = 0.90), clinical status (p = 0.85) or diastolic
function (p = 0.16). Worsening of renal function, NTproBNP, endothelin-1 and uric
acid
sCG Stimulators
DILATE-1
27
2014
Riociguat vs. placebo (single dose)
39
≥18 years, LVEF > 50% and PH; mPAP ≥ 25 mmHg and PCWP > 15 mmHg
30 days
Well tolerated; improved exploratory hemodynamic and echocardiographic parameters;
No impact on mPAP (p = 0.60)
SOCRATES-Preserved
28
2016
Vericiguat vs. placebo
470
LVEF ≥ 45%, NYHA II-IV, elevated natriuretic peptides
12 weeks
No effect on NT-proBNP (p = 0.20) or LA volume (p = 0.37). Some potential in improving
quality of life (p = 0.016), particularly with higher doses
Ranolazine
RALI-DHF
29
2013
Ranolazine vs. placebo
20
LVEF ≥ 45%, E/E` > 15 or NT-proBNP > 220pg/mL,tau ≥ 50ms, LVEDP ≥ 18 mmHg
14 days
Despite hemodynamic improvements at 24 h, there was no effect on diastolic function parameters
B
Clinical Trial
Year
Intervention
Patients, n
Major inclusion criteria
Mean follow-up
Main conclusions
Albuterol
BEAT - HFpEF
30
2019
Albuterol vs. placebo
30
LVEF ≥ 50%, elevated LV filling pressures, PCWP > 15 mmHg and/or ≥ 25 mmHg during
exercise
-
Symptom evaluation through its effect on pulmonary vascular resistance at rest and
during exercise
Shunt
REDUCE LAP-HF I
31
2017
Interatrial septal shunt device vs. sham procedure
94
LVEF>40% and elevated PCWP
1 month
Showed to be safe and effective; Reduction of PCWP (p = 0.028) without significant
increase in PAP or pulmonary vascular resistance
Monitoring
CHAMPION
34
2014
Hemodynamic monitoring vs. control
119
LVEF > 40% (mean 50.6%), NYHA III
17.6 months
Significant reduction in HF hospitalizations (HR 0.50; 95%CI: 0.35-0.70; P < 0.0001)
Exercise
EX DHF
36
2011
Supervised resistance training vs. usual care
64
> 45 years, LVEF ≥ 50%, NYHA II-III, diastolic dysfunction, sinus rhythm and ≥ 1 CV
risk factor
3 months
It showed to be achievable, safe and effective; Improved functional capacity, diastolic
function and quality of life (´p < 0.001)
Comorbidities
OPTIMIZE-HFPEF
38
2016
Systematic screening and optimal treatment of comorbidities vs. usual care
360
>60 years, LVEF ≥ 50%, NYHA II-IV
2 years
Assessment of clinical status
Pacing
RAPID-HF
39
(NCT02145351)
2019
Dual chamber pacemaker with pacing on vs. pacing off
30*
LVEF ≥ 50%, NYHA II-III, diastolic dysfunction and chronotropic incompetence
4 weeks
Assessment of exercise capacity, symptoms and quality of life
Iron Supplementation
FAIR
40
(NCT03074591)
2019
Ferric Carboxymaltose IV vs placebo
200*
LVEF ≥ 45%, NYHA II-III, diastolic dysfunction, iron deficiency, Hb 9-14g/dL
52 weeks
Evaluation of exercise capacity, quality of life, NYHA functional class, mortality
and HF hospitalizations
SGLT2 Inhibitors
EMPERIAL Preserved
46
(NCT03448406)
2019
Empagliflozin vs. placebo
300*
LVEF > 40%, NYHA II-IV, NT-proBNP > 300pg/mL,6 min-walking distance ≤ 350 metros
12 weeks
Assessment of exercise capacity measured by the 6 min-walking distance
Preserved-HF
47
(NCT03030235)
2019
Dapagliflozin vs. placebo
320*
LVEF ≥ 45%, NYHA II-III, NT-proBNP ≥ 225pg/mL or BNP ≥ 75 pg/mL
12 weeks
NT-proBNP evaluation
EMPEROR-Preserved
48
(NCT03057951)
2021
Empagliflozin vs. placebo
6000*
LVEF > 40%, NYHA II-IV, NT-proBNP > 300pg/mL
38 months
Evaluation of CV death and HF hospitalization
AMI: acute myocardial infarction; CAD: coronary artery disease; CO: cardiac output;
CV: cardiovascular; HF: heart failure; HR: hazard ratio; LA: left atrium; LVEF: left
ventricle ejection fraction; mPAP: mean pulmonary artery pressure; NYHA: New York
Heart Association; PAP: pulmonary artery pressure; PCWP: Pulmonary Capillary Wedge
Pressure; 95% CI: 95% confidence interval;
*
Estimated target number.
1. Beta-blockers (BB)
The Randomized trial to determine the effect of nebivolol on mortality and cardiovascular
hospital admission in elderly patients with heart failure, the “SENIORS” trial,
9
evaluated the effect of nebivolol in patients over 70 years with a history of HFrFE
and HFpEF (LVEF > 35%). Despite the reduction in morbidity and mortality, most patients
had reduced LVEF (mean 36%) and a history of coronary artery disease and, thus, it
was not possible to extrapolate the results to patients with true HFpEF. In a meta-analysis
performed later, the BB were the only drugs able to reduce cardiovascular and all-cause
mortality.
10
However, patients with different LVEF were included, so the obtained results might
possibly have been due to pleiotropic effects in patients with HFmrEF. Recently, our
group showed the role of BB in patients with acute coronary syndrome and HFmrEF, demonstrating
a reduction of in-hospital mortality, as well as myocardial revascularization.
11
2. Angiotensin-converting enzyme inhibitor (ACEI)/Angiotensin receptor blocker (ARB)
In spite of the proven efficacy in patients with HFrFE, post-AMI, hypertension and/or
high cardiovascular risk, the benefit in patients with HFpEF is limited.
12
The Effects of candesartan in patients with chronic heart failure and preserved left-ventricular
ejection fraction, the “CHARM-Preserved” trial,
13
showed that candesartan, despite reducing hospital admissions, had no impact on cardiovascular
mortality when compared to placebo. The perindopril in elderly people with chronic
heart failure, the “PEP-CHF” trial
14
evaluated the impact of perindopril in patients with diastolic HF, showing no statistical
benefit on long-term mortality or hospitalization. However, it appeared to improve
symptoms, exercise capacity and HF hospitalization, particularly in younger patients
with a history of AMI or hypertension. In addition, irbesartan showed no benefits
in terms of mortality, hospitalizations or quality of life assessed in the Irbesartan
in Patients with Heart Failure and Preserved Ejection Fraction, the “I-PRESERVE” trial.
12
Another clinical trial showed that 12 months of enalapril had no effect on exercise
capacity, aortic distensibility, ventricular parameters or quality of life.
15
3. Mineralocorticoid/aldosterone receptor antagonists (MRA)
Activation of the mineralocorticoid receptors contributes to the pathophysiology of
HF through sodium and water retention, potassium loss, endothelial dysfunction, inflammation,
fibrosis, and hypertrophy.
16
These patients would be expected to benefit from MRA use. The Effect of Spironolactone
on Diastolic Function and Exercise Capacity in Patients With Heart Failure With Preserved
Ejection Fraction, the “ALDO-DHF” trial,
16
showed advantages in structural reverse cardiac remodeling and improved diastolic
function, but did not affect maximal exercise capacity, patient symptoms, or quality
of life. The study did not have enough power to evaluate the effect of spironolactone
on HF hospitalizations or mortality. The Spironolactone for Heart Failure with Preserved
Ejection Fraction, the “TOPCAT” trial,
17
added more information and assessed the clinical impact of spironolactone on HFpEF.
Although it did not significantly reduce the primary outcome (cardiovascular death,
cardiac arrest or HF hospitalization), a subgroup analysis revealed benefits in patients
with elevated natriuretic peptide levels. These results have led current American
guidelines to consider spironolactone in selected groups of patients with symptomatic
HFpFE, particularly those with high natriuretic peptide levels, aiming to reduce hospitalizations
(Class IIb).
18
4. Angiotensin receptor neprilysin inhibitor (ARNI)
Increasing natriuretic peptide levels with ARNI is expected to improve myocardial
relaxation, natriuresis, vasodilation and attenuation of sympathetic and fibrotic
activity, aiming to improve cardiac function and symptoms. The angiotensin receptor
neprilysin inhibitor LCZ696 in heart failure with preserved ejection fraction”, the
PARAMOUT”
19
trial: a phase II study, randomized 301 patients with HFpEF to receive either ARNI
or valsartan. The primary endpoint, which was the change in NT-proBNP levels at 12
weeks, was significantly better in the sacubitril/valsartan group. At 36 weeks, there
was also a reduction in left atrial (LA) volume, a marker of LV filling pressures,
and an improvement in the NYHA functional class. Angiotensin Receptor Neprilysin Inhibition
in Heart Failure With Preserved Ejection Fraction, the “PARAGON”(20 )trial: a phase
III study, will assess the clinical benefit and safety of this drug in chronic symptomatic
patients with HFpEF.
5. Ivabradine
An elevated heart rate (HR) is a predictive factor of worse outcomes and increased
mortality in patients with heart failure, including those with HFpEF. Ivabradine is
a specific and selective inhibitor of the sinoatrial node, if current, and thereby
decreases HR in patients with sinus rhythm.
21
In patients with HFpEF, short-term treatment increased exercise capacity by improving
LV filling pressures.
22
As these patients are mostly symptomatic during exercise, therapies targeting hemodynamic
changes during exercise may be useful. The Effect of ivabradine in patients with heart
failure with preserved ejection fraction, the “EDIFY” trial,
21
evaluated the effect of the drug over 8 months. Unlike the previous study, there was
no improvement in the evaluated parameters (diastolic function, exercise capacity
and NT-proBNP reduction). Future studies may show benefits in certain subgroups.
6. Digoxin
Digoxin is also part of the therapeutic algorithm in HFrEF, although it is not the
first-line therapy.
3
A potential benefit in patients with diastolic dysfunction and HFpEF could arise from
its neurohormonal action. The Effects of Digoxin on Morbidity and Mortality in Diastolic
Heart Failure, the “DIG PEP” trial,
23
showed no effect on the natural history endpoints, such as mortality and hospitalizations.
Although it was associated with a trend toward reduction in HF hospitalizations, it
did not affect the overall results, partly because of a non-significant increase in
the risk of hospitalization for unstable angina.
7. Nitrates and Nitrites
Another pathophysiological mechanism involved in HFpEF is the deregulation of the
NO-sGC-cGMP-PKG pathway. A possible therapeutic approach would consist in the use
of drugs that act at this level, such as nitrates, phosphodiesterase-5 inhibitors,
riociguat and vericiguat.
The Isosorbide Mononitrate in Heart Failure with Preserved Ejection Fraction, the
“NEAT- HFpEF” trial,
24
evaluated an isosorbide mononitrate regimen, using increasing doses, for 6 weeks.
In addition to the lack of improvement in quality of life or NT-proBNP levels, there
was a reduction in daily activity level and increased HF symptoms. Other mechanisms
eventually limit the hemodynamic benefits of organic nitrates and predispose patients
to excessive hypotension and other adverse effects.
The hypothesis that the results would be better with inorganic nitrates (NO3) was
tested in a pilot study that assessed exercise capacity and the impact on vasculature
and skeletal muscle, using NO3-rich beetroot juice. Although the primary endpoint
was not reached, the results seemed to be positive.
25
It will be important to confirm the results in larger, long-term trials.
8. Sildenafil
Inhibition of phosphodiesterase-5 seems to reverse cardiac remodeling and improve
vascular, neuroendocrine and renal function, with clinical improvement in patients
with idiopathic pulmonary arterial hypertension (PAH) and HFrEF. The Effect of Phosphodiesterase-5
Inhibition on Exercise Capacity and Clinical Status in Heart Failure With Preserved
Ejection Fraction, the “RELAX” trial,
26
evaluated these parameters in patients with HFpEF, comparing sildenafil with placebo
for 24 weeks. Not only was there no improvement in exercise capacity, clinical status,
cardiac remodeling or diastolic function, but also the renal function and NTproBNP,
endothelin-1 and uric acid levels were adversely affected. In the subgroup of patients
with HFpEF and severe pulmonary vascular disease, the results might perhaps be different
and more encouraging.
5
9. sCG Stimulators (Riociguat and Vericiguat)
Pulmonary hypertension (PH) is frequently seen in patients with HF and has been shown
to be a major determinant of worse outcomes, thereby representing a potential novel
therapeutic target in HFpEP. Riociguat is a novel soluble guanylate cyclase (sGC)
stimulator. Its vasodilatory, antifibrotic, antiproliferative and antiinflammatory
effect has shown to be efficient in pulmonary arterial hypertension and chronic thromboembolic
PH with LV systolic dysfunction. The Acute Hemodynamic Effects of Riociguat in Patients
With Pulmonary Hypertension Associated With Diastolic Heart Failure, the “DILATE-1”
trial,
27
evaluated its effect in patients with PH and diastolic dysfunction. It was an initial
study, which assessed a small number of patients and used single doses of riociguat.
Despite being well tolerated and improving exploratory hemodynamic and echocardiographic
parameters, further studies with larger sample sizes and longer duration are needed
to assess its long-term clinical effect.
In the Vericiguat in patients with worsening chronic heart failure and preserved ejection
fraction, the “SOCRATES-Preserved” trial,
28
12 weeks of treatment with vericiguat also did not change the primary endpoints, NT-proBNP
levels and LA volume. Some potential to improve quality of life has been suggested,
particularly at higher doses, which may be tested in further studies, possibly with
higher doses, longer follow-up and additional endpoints.
10. Ranolazine
It is known that both HF and ischemic heart disease show increased late sodium current
on intracellular calcium cycling, compromising cardiac relaxation. By inhibiting the
late sodium channels with ranolazine, an improvement in the diastolic function would
theoretically be expected.
6
The RAnoLazIne for the Treatment of Diastolic Heart Failure in Patients With Preserved
Ejection Fraction, the “RALI-DHF” trial
29
was an exploratory study that evaluated the drug in patients with HFpEF. Despite hemodynamic
improvements after 24 hours, there were no significant changes in diastolic function
after 14 days of treatment.
Another Direction
The failure of clinical trials in testing proven effective drugs in HFrEF, has led
to a new direction in the treatment of patients with HFpEF. Attempts were made to
better understand the pathophysiological mechanism of the disease and act on those
different pathways (Figure 2). New drugs have been tested and new approaches are under
research. (Table 1-B)
Figure 2
Potential therapeutic targets and drugs evaluated in HFpEF. ACEI/ARB: angiotensin-converting
enzyme inhibitors/angiotensin II receptor blocker; ARNI: angiotensin receptor neprilysin
inhibitor; BB: Beta Blockers; MRA: mineralocorticoid receptor antagonists; PH: pulmonary
hypertension.
11. Albuterol
Given the frequent lung involvement in these patients, drugs acting at this level
are being tested. This is the case of albuterol, an inhaled bronchodilator. The Inhaled
Beta-adrenergic Agonists to Treat Pulmonary Vascular Disease in Heart Failure With
Preserved EF, the “BEAT - HFpEF” trial,
30
aims to assess the impact of this drug on symptoms, through its effect on pulmonary
vascular resistance at rest and during exercise.
12. Interatrial septal shunt
It is known that the atrial volume and pressure overload not only contributes to the
development of symptoms and exercise intolerance, but it is also a major determinant
of morbimortality. Pulmonary capillary wedge pressure (PCWP) is an invasive hemodynamic
parameter with prognostic value, which reflects the pressure in the LA and pulmonary
veins. Based on these hemodynamic changes and in view of the limited success of pharmacological
management of patients with HFpEF, an interatrial communication device was developed,
which is used to reduce LA pressure. The prospective, non-randomized, open-label study,
called “A Transcatheter Intracardiac Shunt Device for Heart Failure with Preserved
Ejection Fraction “REDUCE LAP-HF”
31
evaluated the performance and safety of this device in 64 patients with HFpEF and
elevated PCWP. Preliminary analyses demonstrated clinical and hemodynamic benefits
at 6 months. Pressure reductions in LA resulted in improved functional capacity, at
the expense of a slight increase in the right cardiac pressure and output. These benefits
persisted in a long-term evaluation with sustained improvement of the hemodynamic
profile, NYHA functional class, quality of life and exercise capacity at the end of
one year, with no evidence of complications.
32
Subsequently, a randomized controlled phase II trial was performed with PCWP evaluation
during exercise, one month after the implantation of the interatrial septal shunt
device vs. sham procedure. It showed to be safe and effective, with a reduction of
PCWP and without a significant increase in pulmonary artery pressure (PAP) or pulmonary
vascular resistance, which are possible consequences of right cardiac overload.
33
It remains unclear whether this hemodynamic effect will lead to sustained clinical
improvements.
13. Monitoring
Congestive symptoms are present in the majority of patients hospitalized for decompensated
HF regardless of LVEF. Changes in body volume and cardiac filling pressures are predictive
of adverse events. A strategy of hemodynamic monitoring, with consequent targeted
and early therapeutic intervention, may reduce the risk of hospitalization for HF.
TheWireless pulmonary artery haemodynamic monitoring in chronic heart failure, the
“CHAMPION” trial,
34
tested this hypothesis by using a microelectromechanical system pressure sensor permanently
implanted during right cardiac catheterization. Through daily assessment of PAP and
active reduction of filling pressures with diuretics and vasodilators, significant
reductions were demonstrated in hospital admissions. The benefits persisted in the
subgroup of patients with HFpEF, with reductions of 50% in HF hospitalizations after
17 months.
35
14. Exercise
Physical exercise is beneficial in certain conditions strictly related to HFpEF, such
as hypertension and metabolic syndrome. The effect of structured and supervised training
on exercise capacity, diastolic function and quality of life was evaluated. The Exercise
Training Improves Exercise Capacity and Diastolic Function in Patients With Heart
Failure With Preserved Ejection Fraction, the “EX DHF” trial,
36
showed that a short-term supervised endurance/resistance training is achievable, safe,
and effective in patients with HFpEF. The program maintenance in the long term and
the involvement of elderly patients, at advanced stages of the disease and with multiple
comorbidities, are possible limitations. Nevertheless, it seems a promising strategy
with potential synergism with other pharmacological and non-pharmacological approaches.
It is important to define the regimen approach, improve long-term adherence and expand
availability.
37
15. Comorbidities
Another of the proposed pathophysiological mechanisms involves the existence of a
systemic proinflammatory state induced by multiple comorbidities, resulting in endothelial
dysfunction, cardiac remodeling and dysfunction. It was hypothesized that by screening
and treating comorbidities in a targeted manner, the overall prognosis of these patients
could be improved. The Optimizing the Management of Heart Failure with Preserved Ejection
Fraction in the Elderly by Targeting Comorbidities, the “OPTIMIZE-HFpEF” trial,
38
proposes a systematic screening and optimized treatment of comorbidities as a pathophysiological
mechanism of HF, rather than the simple treatment of previously diagnosed concomitant
pathologies. Although it lacks sufficient power to assess cost-effectiveness, it is
a good starting point to test a new promising approach.
16. Pacing
Patients with HFpEF and chronotropic incompetence may benefit from pacemaker devices,
which may help to restore the normal HR during daily activity and exercise. The Rate-Adaptive
Atrial Pacing In Diastolic Heart Failure (RAPID-HF) trial
39
aims to evaluate the impact of this intervention on short-term exercise capacity,
symptoms and quality of life.
17. Iron Supplementation
Iron kinetics is part of the initial evaluation of patients with HF. Intravenous iron
supplementation is part of the therapeutic approach in patients with HFrEF and reduced
iron stores.
3
The Effect of IV Iron Ferric Carboxymaltose (Ferinject) on Exercise Tolerance, Symptoms
and Quality of Life in Patients With Heart Failure With Preserved Ejection Fraction
and Iron Deficiency With and Without Anaemia, the “FAIR” trial,
40
aims to evaluate the effect of intravenous iron on exercise capacity, quality of life,
NYHA functional class, mortality and hospitalizations for HF in patients with HFpEF
and iron deficiency, with or without anemia.
18. Sodium-glucose cotransporter-2 inhibitors (SGLT2i)
HF and diabetes frequently coexist, associated with an increased risk of cardiovascular
mortality and HF hospitalization.
41
Several studies with SGLT2 inhibitors have demonstrated a significant reduction in
HF hospitalizations in diabetic patients at high cardiovascular risk or with established
cardiovascular disease (Empagliflozin, Cardiovascular Outcomes, and Mortality in Type
2 Diabetes “EMPA-REG”,
42
Canagliflozin and Cardiovascular and Renal Events in Type 2 Diabetes “CANVAS”,
43
Dapagliflozin and Cardiovascular Outcomes in Type 2 Diabetes “DECLARE”
44
trials). Given the potential benefits of this pharmacological group in improving diastolic
function in patients with HF,
45
studies are underway to determine the impact of these drugs in patients with HFpEF,
with and without diabetes (A Phase III Randomised, Double-blind Trial to Evaluate
the Effect of 12 Weeks Treatment of Once Daily EMPagliflozin 10 mg Compared With Placebo
on ExeRcise Ability and Heart Failure Symptoms, In Patients With Chronic HeArt FaiLure
With Preserved Ejection Fraction (HFpEF) “EMPERIAL - Preserved”,(
46
) Dapagliflozin in PRESERVED Ejection Fraction Heart Failure “PRESERVED-HF”,(
47
) EMPagliflozin outcomE tRial in Patients With chrOnic heaRt Failure With Preserved
Ejection Fraction “EMPEROR-Preserved”(
48
).
Conclusions
HFpEF is a common pathology, still poorly understood and without any treatment proven
to be effective in reducing morbidity or mortality.
There seems to be no single cause to justify the failure of the obtained results;
however, potential contributions can be identified: incomplete understanding of the
pathophysiology, heterogeneity of the studied population, lack of universal diagnostic
criteria with recruitment of patients without true HFpEF or at the very early stages,
treatment not targeting the predominant pathophysiological mechanism, suboptimal designs
or weak statistical power of the trials.
The pathophysiology of HFpEF is multifactorial, with several mechanisms and comorbidities
involved, and probably different from those of HFrEF. It results from a complex interaction
of factors that culminate in the reduction of cardiac and vascular functional reserve
- systolic and diastolic dysfunction, atrial reserve, heart rate and rhythm, autonomic
control, vasculature and microcirculation. The interaction and relative dominance
of these factors make this pathology extremely heterogeneous. The definition and division
into subgroups with certain phenotypes may allow a more targeted treatment, with possible
improvement of the clinical results.
Several clinical trials are being carried out, using different therapeutic approaches.
It is important to remember that these patients tend to be older and have multiple
pathologies. Thus, the benefit of the treatments may be better evaluated by their
effect on hospitalizations, functional status, symptoms and quality of life.