Torsades de pointes after transcatheter aortic valve implantation in the setting of new-onset complete left bundle branch block: a multifactorial proarrhythmic case report

New-onset complete left bundle branch block (CLBBB) is a known complication of transcatheter aortic valve implantation (TAVI). Its role in precipitating life-threatening arrhythmias such as Torsades de Pointes (TdP), especially within a multifactorial clinical context, requires careful methodological interpretation. We present a case of a 71-year-old female who developed new-onset CLBBB and a markedly prolonged Bazett-corrected QTc of 523 ms immediately post-TAVI. Because QRS widening itself prolongs the measured QT interval, the Wang LBBB-specific QT correction was applied. The LBBB-adjusted QTc was 467 ms, indicating that a substantial portion of the apparent Bazett-QTc prolongation was attributable to QRS widening; Wang et al. reported that the net QRS increase accounts for approximately 92% of QTc prolongation in LBBB. JT/JTc were also examined but may underestimate total repolarization time when QRS is wide. On day 4, in the presence of multiple coexisting acquired risk factors — third-degree atrioventricular block (AVB), hypokalemia, Gram-negative bacteremia, fever, and catecholamine infusion — the patient developed TdP that degenerated into ventricular fibrillation and cardiac arrest, requiring cardiopulmonary resuscitation. Management must focus aggressively on correcting all reversible acquired factors, with temporary pacing as an adjunctive measure for bradycardia-dependent QT prolongation; importantly, TdP occurred despite active pacing, underscoring the contribution of non-bradycardic triggers. In this multifactorial context, CLBBB likely acted as a synergistic contributor rather than the sole dominant cause of TdP.