Electrical storm in patients with hypertrophic cardiomyopathy

Data about ES in hypertrophic cardiomyopathy (HCM) patients are scarce and restricted to case reports and cases series, limiting the ability to optimize therapeutical strategy in such situation. We aimed at analyzing the acute management and long-term outcomes of HCM patients with ES.

This multicenter retrospective observational study included all consecutive patients admitted in the intensive care units of six tertiary centers for the management of ES in the context of HCM between January 2010 and March 2023. Data were collected from medial files. The primary endpoint of this study was in-hospital survival after ES. Secondary endpoints included in-hospital complications, and one-year survival.

A total of 23 patients were included (73.9% male, aged 61.5±15.2 years, LVEF 50.0±14.0%, 8 (34.8%) genetic mutations identified [4 MYBPC3, 2 TNMT2, 1 LMNA, 1 FLNC]). Ten (43.4%) and 3(13%) had a history of VAs and ES, respectively. Six (26.1%) patients previously had a catheter ablation of VAs.

At admission, the arrhythmias responsible for the ES were monomorphic VTs (18 patients, 78.3%) and/or VF (7 patients, 30.4%). Twenty (87.0%) patients received amiodarone, 16 (70.0%) beta-blockers, 9 (39.1%) lidocaine, and 8 (34.8%) magnesium sulfate. The severity of ES required autonomic modulation in 1 (4.3%) patient and deep sedation with intubation in 3 (13.0%) patients. Five patients had a cardiogenic shock requiring vasoactive drugs, while 2 needed ECMO implantation. Ten patients (43.5%) had a radiofrequency ablation, with ventricular stimulation inducing VTs in 6 (60%) patients. A scared area was found in 7 (70%) of the patients, located in the apex (5 patients), the left ventricular outflow tract (1 patient) and the postero-septal region (1 patient). Radiofrequency was delivered in all patients but 2 with clear epicardial VT origin. Ablation was an acute success in 3 (30%) patients, a partial success in 1 (10%) patient, a failure in 3 (20%) patients, and undetermined in 3 (30%) patients. One patient had a post procedural tamponade requiring percutaneous drainage.

During a median follow-up of 18 months, 7 recurrences of sustained VT occurred. Four patients experienced recurrences despite ablation. One patient underwent heart transplantation two months later due to persistent ventricular arrhythmias. Among the patients discharged from hospital, 4 died, mainly from end-stage heart failure. At one year, the Kaplan-Meier survival curve showed that 82.7% of patients were still potentially alive. Over a median follow-up of 18 months, 26% of the study patients had died.

Most HCM patients having ES have advanced cardiomyopathy and had previously experienced episodes of VAs. Ablation may be an interesting option but is likely less effective in the context of an ES, with a 50% recurrence rate of VT during follow-up. Death is more likely to occur due to heart failure rather than arrhythmic causes.