Background: Both acute myocardial infarction complicated by ventricular tachyarrhythmias (AMI-VTA) and electrical storm (ES) represent life-threatening clinical conditions. However, a direct comparison of both sub-groups regarding prognostic endpoints has never been investigated. 

Methods: All consecutive implantable cardioverter-defibrillator (ICD) recipients were included retrospectively from 2002 to 2016. Patients with ES apart from AMI (ES) were compared to patients with AMI accompanied by ventricular tachyarrhythmias (AMI-VTA). The primary endpoint was all-cause mortality at 3 years, secondary endpoints were in-hospital mortality, rehospitalization rates and major adverse cardiac event (MACE) at 3 years.

Results: A total of 198 consecutive ICD recipients were included (AMI-VTA: 56%; ST-segment elevation myocardial infarction (STEMI): 22%; non-ST-segment myocardial infarction (NSTEMI) 78%; ES: 44%). ES patients were older and had higher rates of severely reduced left ventricular ejection fraction (LVEF) <35%. ES was associated with increased all-cause mortality at 3 years (37% vs. 19%; p=0.001; hazard ratio [HR]=2.242; 95% CI 2.291-3.894; p=0.004) and with increased risk of first cardiac rehospitalization (44% vs. 12%; p=0.001; HR=4.694; 95% CI 2.498-8.823; p=0.001). This worse prognosis of ES compared to AMI-VTA was still evident after multivariable adjustment (long-term all-cause mortality: HR=2.504; 95% CI 1.093-5.739; p=0.030; first cardiac rehospitalization: HR=2.887; 95% CI 1.240-6.720; p=0.014). In contrast, the rates of MACE (40% vs. 32%; p=0.326) were comparable in both groups.

Conclusion: At long-term follow-up of 3 years, ES was associated with higher rates of all-cause mortality and rehospitalization compared to patients with AMI-VTA.