Introduction
Transcatheter aortic valve implantation (TAVI) includes the risk for development of
heart block. The presence of left bundle branch block (LBBB) after TAVI with PQ interval
prolongation is not clearly defined as an indication for pacemaker implantation.
Case report
A 76-year-old woman with a combined aortic valve disease, with a predominance of severe
aortic stenosis, who had been previously disqualified from the classical cardiac surgery
of aortic valve replacement because of the high risk of the procedure, was qualified
for transcatheter aortic valve implantation (TAVI) due to increasing symptoms of heart
failure. Moreover, she had a history of long-term arterial hypertension, symptomatic
heart failure (NYHA II/III), rheumatoid arthritis (RA) and degeneration of the spine
in the thoracic-lumbar part and lumbar scoliosis limiting her mobility. Baseline ECG
revealed: regular sinus rhythm 70 bpm, the mean electrical axis in the frontal plane
= ‘–20°’, PQ interval = 170 ms, QRS = 98 ms, QTc = 410 ms. The baseline echocardiography
examination revealed left ventricular (LV) hypertrophy (LV = 42 mm, posterior wall
(PW) of LV = 14 mm, interventricular septum (IVS) = 15 mm), significantly stenotic,
extremely calcified aortic valve (peak pressure gradient (PPG) = 174 mm Hg, mean PG
(MPG) = 101.2 mm Hg, and Vmax = 6.6 m/s) with good ejection fraction (EF) of the LV
(EF – 65%). Computed tomography scans disclosed multiple calcifications of the aortic
valve (Figure 1 A) and within the coronary sinus area (aortic valve area 417 mm2,
perimeter 23.4 mm). Operative mortality was estimated using the following scoring
systems: Euro SCORE standard = 7 p., logistic [%] = 6.19%, EUROSCORE II = 2.11%, STS
score mortality [%] = 11.12%, mortality & morbidity = 58.526. The TAVI was carried
out in general anesthesia from a femoral approach using the Prostar system. Before
valve implantation balloon aortic valvuloplasty using Numed Z-Med II-X 18 mm × 50
mm was performed. Following that a CoreValve 29 mm was implanted (the depth of implantation
calculated on computed tomography scan was 4 mm), which resulted in a complete elimination
of the transvalvular gradient with a trace of paravalvular aortic regurgitation. There
were no complications of the procedure.
Figure 1
A – Computed tomography scan of ascending aorta with calcified aortic valve. B – Chest
X-ray examination of the heart in anterior-posterior projection; CoreValve prosthesis
of aortic valve and quadripolar, diagnostic catheters during electrophysiological
study located on the high right atrium (HRA), in the His area (HBE) and in the apex
of the right ventricle (RV) are visualized
On the first day after TAVI the patient’s general condition was good. ECG revealed:
regular sinus rhythm 86 bpm, new onset of left bundle branch block (LBBB) with QRS
complex prolongation from 96 to 173 ms (Figure 2 A) and QTc = 465 ms. For the next
5 days the patient remained in a good general condition. Physical rehabilitation started
on the second day after the TAVI procedure. Continuous ECG monitoring was applied
throughout the patients’ stay in the cardiac intensive care unit. On the 6th day an
episode of pre-syncope (lightheadedness and dizziness lasting approximately 15 to
20 s) occurred. Its mechanism remained unknown since the patient had unplugged the
ECG while going to a rest room. The ECG showed: regular sinus rhythm 64 bpm, with
PQ interval prolongation to 194 ms, LBBB with QRS complex prolongation to 173 ms (Figure
2 A) and QTc = 473 ms. The 24 h Holter-ECG monitoring did not reveal any other arrhythmias
or conduction abnormalities. On the 7th day 2 more pre-syncope episodes occurred (during
normal activities, with no ECG tracing). The patient complained of a short onset of
heart palpitation prior to the pre-syncope episode. Lacking ECG documentation of these
episodes and considering the patient’s safety, the decision of invasive electrophysiology
(EP) testing was made. The EP was performed on the 8th day after TAVI, after obtaining
the patient’s informed consent. Three quadripolar, diagnostic catheters were used
with the diameter of 6 Fr located on the right atrium (HRA), in the His area (HBE)
and in the apex of the right ventricle (RV) – Figure 1 B. Baseline ECG during EP:
sinus rhythm with LBBB. PQ interval varied and ranged from 205 to 220 ms, QRS = 173
ms (LBBB), QTc = 494 ms, RR = 1000 ms, AH interval = 128 ms, HV interval = 62 ms.
Right ventricle stimulation (PCL 800+S2 and 700+S2) with no retrograde conduction.
Effective refractory period RV = 300 ms. Each stimulation of the right atrium resulted
in an immediate progression of AV block to advanced second-degree AV block. During
EP examination a variable PQ interval was observed (with maximum prolongation to 318
ms) and HV interval from 60–70 ms to 160 ms. Having positioned the electrodes towards
the apex of the right ventricle and His area (HBE) a dynamic increase of infra-Hisian
and advanced second-degree AV block occurred with AV conduction 11 : 1; 6 : 1 (advanced
second-degree AV block with maximal RR interval up to 10.4s) – Figure 2 B. Apart from
LBBB multilevel AV conduction disturbances were found, with domination of advanced
AV distal-type block. No arrhythmias were induced during the electrophysiological
study.
Figure 2
A – Electrocardiogram (paper speed 25 mm/s) before transcatheter aortic valve implantation
(TAVI), on days 6 and 8 after TAVI; left bundle branch block progression with PQ interval
prolongation to 194 ms on day 6. Also, with a more intense prolongation of PQ interval
to 220 ms followed by an episode of syncope (day 8). B – ECG (paper speed 13 mm/s)
spontaneous advanced second-degree atrioventricular block with 10.4 s gap
After the EP study the patient was secured with an electrode for temporary pacing
and underwent a DDD pacemaker implantation on the 8th day after TAVI. The patient’s
rehabilitation and recovery on subsequent days were uneventful. Follow-up at 1 month
and 6 months in the outpatient clinic revealed 99% up to 100% of right ventricular
pacing.
Discussion
Here we present the analysis of clinical progression of the ECG changes in a patient
after TAVI (CoreValve) who had a pre-syncope episode on the 6th and 7th days after
valve replacement. It was necessary to make a decision whether to implant a pacemaker
and, if so, when to do it. Although the literature data suggest that LBBB occurrence
after TAVI is frequent (14–83%) [1], there are no clear criteria relating to the optimal
time of elective pacemaker implantation and advisability of this procedure. The presence
of right bundle branch block (RBBB) before TAVI is a factor correlating with an increased
risk for pacemaker implantation [2]. RBBB, however, was not present in our case. According
to the literature, patients who received CoreValve and Lotus devices have higher risk
of AV conduction disturbances requiring pacemaker implantation (19.2% to 42.5%) in
comparison to the Sapien valve (1.8% to 8.5%) [3, 4].
The presence of LBBB after TAVI is a common finding, and LBBB coexisting with PQ interval
prolongation is not clearly defined as an indication for PM implantation. The EP testing
revealed a vast area of heart tissues with damaged electrophysiological properties
causing AV conduction abnormalities such as multilevel AV block, possibly developing
into a third-degree AV block. Probably, the mechanism of AV conduction disorders is
complex. Any direct mechanical trauma or compression to the His bundle related to
a self-expandable valve prosthesis in the region of the membranous septum and right
trigone beneath the noncoronary/right coronary cups and the area of the upper 1/3
of the intra-ventricular septum needs to be considered. Significant calcification
of aortic valve leaflets may also contribute to conduction disturbances. Therefore,
the optimal valve implantation in the LVOT above the His bundle is crucial. The location
of the His bundle and its distal part with branches in the intraventricular septum
near the left ventricle endocardium is another important issue. It can be assumed
that severe concentric hypertrophy of the LV (the dimension of IVS) distinctive in
aortic stenosis, in patients with good EF, may affect the conductive system at various
levels. Eventually, the insertion of diagnostic electrodes for the EP testing may
also contribute to exertion of mechanical pressure on tissues. However, dynamic progression
of AV block is not observed in routine EP examination.
In this case, the EP testing was a useful tool to take the final decision to implant
a pacemaker. However, in our opinion, this strategy may be used in selective cases
in the early period after TAVI to reduce the number of unnecessary pacemaker implantations.
According to the statement from the 2013 ESC Guidelines on cardiac pacing and cardiac
resynchronization therapy [5]:
An intrinsic AV block should be differentiated from the other known forms of the block,
namely, vagal (extrinsic) and idiopathic AV block. The infra-Hisian block by EPS supports
a diagnosis of intrinsic AV block.
The presence of bundle branch block (BBB), unexplained syncope and non-diagnostic
investigations; pacing may be considered in selected patients with unexplained syncope
and BBB (class II b, level B).
Asymptomatic BBB; pacing is not indicated for BBB in asymptomatic patients (class
III, level B).
Therefore, in such specific clinical situations, a question arises: what is the proper
action? An individual approach to each patient seems to be the best answer.
Conclusions
In patients after the TAVI procedure (particularly with CoreValve) in the presence
of LBBB and prolonged PQ interval, EP study may be considered to establish the indication
for PM implantation.