A practical 5-stage clinical scale for electrical storm: the STORM classification

Electrical storm (ES) is a highly heterogeneous condition with wide-ranging clinical presentations. The absence of standardized classification hampers risk stratification and limits effective multidisciplinary coordination.

The aim of this study was to develop a classification system based on simple clinical characteristics and stratify 30-day mortality in patients with ES.

Patients admitted to intensive care units for ES between 2010 and 2023 across four tertiary centres were retrospectively included. The five-stage STORM severity-response classification, based on treatment intensity during hospitalization, incorporated four clinically relevant parameters: signs of acute heart failure or haemodynamic instability, need for inotropes or vasopressors, use of advanced supportive therapies (including deep sedation) and renal replacement therapy, and implementation of mechanical circulatory support. The primary outcome was all-cause mortality at 30 days. A total of 788 patients were included. The cohort was predominantly male (84.3%), with a median age of 66.0 years (57.0-74.0). The majority had ischaemic cardiomyopathy (65.6%), with a median LVEF of 30.0% (20.0-45.0). According to the STORM classification, 421 patients (53.4%) were categorized as STORM-1, 45 (5.7%) as STORM-2, 86 (10.9%) as STORM-3, 220 (27.9%) as STORM-4 and 16 (2.0%) as STORM-5. Overall, 117 patients (14.8%) died within 30 days. A stepwise increase in 30-day mortality was observed across STORM stages - 5.0%, 6.7%, 20.9%, 30.5% and 50.0% for stages 1 through 5, respectively (P < 0.01).

The STORM classification may facilitate standardized multidisciplinary management strategies and effectively stratifies 30-day mortality risk in patients with ES, ranging from 5% in stage 1% to 50% in stage 5. Further prospective studies are warranted to validate our findings.