The Temporal Relation between Cardiomyopathy and LBBB and Response to Cardiac Resynchronization Therapy: Case Series and Literature Review

Background: Left bundle branch block (LBBB)-induced cardiomyopathy has been proposed, but the association between LBBB and cardiac resynchronization therapy (CRT) response remains unclear and practical criteria for selecting CRT candidates are needed. Methods: One hundred and seventeen consecutive heart failure patients were reviewed, 24 of whom received CRT. Only two patients had a clear temporal relation between cardiomyopathy and LBBB. Results: Compared with the patient with “cardiomyopathy-induced LBBB,” the patient with “LBBB-induced cardiomyopathy” had higher left ventricular (LV) wall thickness, higher LV wall thickening rate, higher peak circumferential strain, and longer peak circumferential strain delay. The LV deformation patterns in the two patients were obviously distinct on cardiovascular magnetic resonance tissue tracking. During follow-up, the patient with LBBB-induced cardiomyopathy had a good response to CRT (LV ejection fraction 23 before CRT vs. 30% at 6 months vs. 29 at 12 months vs. 32% at 18 months; LV end-diastolic diameter 77 mm before CRT vs. 66 mm at 6 months vs. 62 mm at 12 months vs. 63 mm at 18 months), and the other patient had no response to CRT (LV ejection fraction 29 before CRT vs. 29% at 6 months vs. 26 at 12 months vs. 22% at 24 months; LV end-diastolic diameter 85 mm before CRT vs. 88 mm at 6 months vs. 85 mm at 12 months vs. 84 mm at 24 months). Conclusion: The temporal relation between cardiomyopathy and LBBB could be a determinant for CRT response. Cardiovascular magnetic resonance tissue tracking may be a useful tool to identify the chronological order and a principal consideration for selecting candidates for CRT. Larger prospective clinical trials are needed to study the prevalence of, time course of, and risk factors for LBBB-induced cardiomyopathy

Feasibility study of temporary permanent pacemaker in patients with conduction block after TAVR

BackgroundLimited data exist on the use of temporary permanent pacemaker (TPPM) to reduce unnecessary PPM in patients with high-degree atrioventricular block (HAVB) after transcatheter aortic valve replacement (TAVR).ObjectivesThis study aims to determine the feasibility of TPPM in patients with HAVB after TAVR to provide prolonged pacing as a bridge.Materials and methodsOne hundred and eleven consecutive patients undergoing TAVR were screened from August 2021 to June 2022. Patients with HAVB eligible for PPM were included. TPPM were used in these patients instead of conventional temporary pacing or early PPM. Patients were followed up for 1 month. Holter and pacemaker interrogation were used to determine whether to implant PPM.ResultsTwenty one patients met the inclusion criteria for TPPM, of which 14 patients were third-degree AVB, 1 patient was second-degree AVB, 6 patients were first degree AVB with PR interval > 240 ms and LBBB with QRS duration > 150 ms. TPPM were placed on the 21 patients for 35 ± 7 days. Among 15 patients with HAVB, 26.7% of them (n = 4) recovered to sinus rhythm; 46.7% (n = 7) recovered to sinus rhythm with bundle branch block. The remains of 26.7% patients (n = 4) still had third-degree AVB and received PPM. For patients with first-degree AVB and LBBB, PR interval shortened to < 200 ms in all 6 patients and LBBB recovered in 2 patients. TPPM were successfully removed from all patients and no procedure-related adverse events occurred.ConclusionTPPM is reliable and safe in the small sample of patients with conduction block after TAVR to provide certain buffer time to distinguish whether a PPM is necessary. Future studies with larger sample are needed for further validation of the current results