1Universitätsklinikum OWL Klinik für Kardiologie und intern. Intensivmedizin Bielefeld, Deutschland; 2Universität Bielefeld Biostatistics and Medical Biometry Bielefeld, Deutschland
Background: Patients (pts) with hypertrophic obstructive cardiomyopathy (HOCM) who undergo alcohol septal ablation (ASA) are at risk for high-degree atrioventricular (AV) block. Therefore, 14-28% of pts require permanent pacemaker (PPM) after ASA [1]. Since most HOCM pts undergo ASA at a young age, devices are frequently implanted for decades. This may be associated with an increased risk of long-term device complications, e.g. infection. It is unclear whether AV block persists in all pts after ASA or if AV conduction may recur after ASA in a subset of pts.
Objective: In this retrospective study we assessed the persistence of AV block after ASA over a minimum 6-week period and correlated the need for permanent pacing to pts baseline characteristics.
Methods: Pts who underwent ASA at our institution between 2016 and 2023 and received postprocedural PPM due to AV block were retrospectively enrolled. Baseline characteristics (age, sex, pre-procedural ECG) and % ventricular pacing (%VP) obtained from PPM readouts at minimum 6 weeks post ASA were collected. Potential associations between baseline characteristics and %VP were analyzed by linear regression.
Results: 464 consecutive pts underwent ASA; 95 of these required implantation of a dual-chamber PPM or implantable cardioverter defibrillator (ICD) due to high-degree AV block induced by ASA, i.e. 20.4%. Of these 95 patients, 38 had a follow-up (FU) at least 6 weeks after device and were thus available for inclusion in the study. Only 14 of these 38 patients (36.8%) still required ventricular pacing, defined as %VP>1. Of these 14 patients, 5 (35.8%) were constantly dependent on ventricular pacing, i.e. they had 100% VP. In contrast, 24 patients (63%) had <1% VP, 21 (55%) <0.1% VP (see Figure 1). Median age of all pts was 58.5 years and 55% of the pts (n=21) were male. Men had a trend for higher %VP during FU (regression coefficient 8.43 (-16.92; 33.78), p=0.50). In contrast, there was a clear association between preexisting ECG abnormalities and %VP during FU: Presence of left bundle branch block (LBBB) significantly increased the likelihood of persistent AV block, with patients having a 34% higher mean %VP than patients without initial ECG pathology (regression coefficient 34.44 (2.41; 66.37), p = 0.036). Moreover, 9 of 20 (=45%) AV blocks that already occurred intraprocedurally led to a high %VP during follow-up (regression coefficient 14.52, p=0.35).
Conclusion: In this small series, persistence of high-degree AV block after ASA was surprisingly low. Only 14 pts (36%) had >1% VP at FU: whereas 21 pts (55%) had < 0.1% VP. These findings may indicate a yet unexpected potential of recovery of AV nodal conduction after ASA. This raises the question whether PPM or ICD replacement is necessary in all pts after ASA or if some pts may be safe without PPM thus preventing possible long-term complications. Prospective studies in larger pts numbers and with longer FU are necessary to confirm these results.
Table 1:
|
|
Overall (n=38) |
Persisting AV block at FU (n=14, 37%) |
No AV block at FU (n=24, 63%) |
|
Women, n (%) |
17 (45%) |
6 (35%) |
11 (65%) |
|
Men, n (%) |
21 (55%) |
8 (29%) |
13 (62%) |
|
Age (years), median (Q1; Q3) |
58,5 (51,0; 65,0) |
59,5 |
55 |
|
Intraprocedural AV block, n (%) |
20 (53%) |
9 (45%) |
11 (55%) |
|
Post-procedural AV block, n (%) |
19 (47%) |
4 (21%) |
15 (79%) |
|
Preexisting LBBB, n (%) |
8 (21%) |
4 (50%) |
4 (50%) |
|
Preexisting RBBB, n (%) |
6 (16%) |
4 (67%) |
2 (33%) |
|
Preexisting AV block I°, n (%) |
2 (5%) |
1 (50%) |
1 (50%) |