Left atrial dilatation in systolic heart failure: a marker of poor prognosis, not just a buffer between the left ventricle and pulmonary circulation

This study sought to define the prevalence, severity, and significance of pulmonary hypertension (PH) in heart failure with preserved ejection fraction (HFpEF) in the general community. Although HFpEF is known to cause PH, its development is highly variable. Community-based data are lacking, and the relative contribution of pulmonary venous versus pulmonary arterial hypertension (HTN) to PH in HFpEF is unknown. We hypothesized that PH would be a marker of symptomatic pulmonary congestion, distinguishing HFpEF from pre-clinical hypertensive heart disease. This community-based study of 244 HFpEF patients (age 76 +/- 13 years; 45% male) was followed up using Doppler echocardiography over 3 years. Control subjects were 719 adults with HTN without HF (age 66 +/- 10 years; 44% male). Pulmonary artery systolic pressure (PASP) was derived from the tricuspid regurgitation velocity and PH defined as PASP >35 mm Hg. Pulmonary capillary wedge pressure (PCWP) was estimated from the ratio of early transmitral flow velocity to early mitral annular diastolic velocity. In HFpEF, PH was present in 83% and the median (25th, 75th percentile) PASP was 48 (37, 56) mm Hg. PASP increased with PCWP (r = 0.21; p < 0.007). Adjusting for PCWP, PASP was higher in HFpEF than HTN (p < 0.001). The PASP distinguished HFpEF from HTN with an area under the receiver-operating characteristic curve of 0.91 (p < 0.001) and strongly predicted mortality in HFpEF (hazard ratio: 1.3 per 10 mm Hg; p < 0.001). PH is highly prevalent and often severe in HFpEF. Although pulmonary venous HTN contributes to PH, it does not fully account for the severity of PH in HFpEF, suggesting that a component of pulmonary arterial HTN also contributes. The potent effect of PASP on mortality lends support for therapies aimed at pulmonary arterial HTN in HFpEF.

Left ventricular (LV) diastolic dysfunction is prevalent in the community. Current assessment of diastolic function can be complex, involving Doppler evaluation of an array of hemodynamic data. The relation between left atrial (LA) volume and diastolic function, and between LA volume and cardiovascular risk and disease burden are not well known. In the present prospective study of 140 adults, mean age 58 +/- 19 years, referred for a clinically-indicated echocardiogram and in sinus rhythm, with no history of atrial arrhythmias or valvular heart disease, we determined the LA volume, LV diastolic function status, cardiovascular risk score (based on age, gender, history of systemic hypertension, diabetes mellitus, hyperlipidemia, and smoking), and cardiovascular disease burden (based on confirmed vascular disease, congestive heart failure, and transient ischemic attack or stroke). LA volume was found to correlate positively with age, body surface area, cardiovascular risk score, LV end-diastolic and end-systolic dimensions, LV mass, diastolic function grade, tissue Doppler E/E', tricuspid regurgitation velocity, and negatively with LV ejection fraction (all p <0.006). In a multivariate clinical model, LA volume indexed to body surface area (indexed LA volume) was independently associated with cardiovascular risk score (p <0.001), congestive heart failure (p = 0.014), vascular disease (p = 0.012), transient ischemic attack or stroke (p = 0.021), and history of smoking (p = 0.008). In a clinical and echocardiographic model, indexed LA volume was strongly associated with diastolic function grade (p <0.001), independent of LV ejection fraction, age, gender, and cardiovascular risk score. In patients without a history of atrial arrhythmias or valvular heart disease, LA volume expressed the severity of diastolic dysfunction and provided an index of cardiovascular risk and disease burden.

Pulmonary hypertension (PH), a common complication of left heart diseases (LHD), negatively impacts symptoms, exercise capacity, and outcome. Although the true prevalence of PH-LHD is unknown, a subset of patients might present significant PH that cannot be explained by a passive increase in left-sided filling pressures. The term "out-of-proportion" PH has been used to identify that population without a clear definition, which has been found less than ideal and created confusion. We propose a change in terminology and a new definition of PH due to LHD. We suggest to abandon "out-of-proportion" PH and to distinguish "isolated post-capillary PH" from "post-capillary PH with a pre-capillary component" on the basis of the pressure difference between diastolic pulmonary artery pressure and pulmonary artery wedge pressure. Although there is no validated treatment for PH-LHD, we provide insights into management and discuss completed and randomized trials in this condition. Finally, we provide recommendations for future clinical trials to establish safety and efficacy of novel compounds to target this area of unmet medical need. Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.