Cor Vasa 2026, 68(2):166-172 | DOI: 10.33678/cor.2025.133

Clinical predictors of appropriate electrical storm in patients with implantable cardioverter defibrillator

Nawar A. Hamed^a, Ali Abdul-Ameer Al Mousawi^b, Kasim Abbas Ismail Al-Iqabby^b, Adil Hassan Al-Husseiny^c

^a Al-Basrah Cardiac Centre, Basra, Iraq

^b Ibn Al-Bitar Cardiac Centre, Baghdad, Iraq

^c College of Medicine, University of Diyala, Iraq

Background: Appropriate electrical storm (ES) in patients with implantable cardioverter-defi brillators (ICDs) is a life-threatening condition characterized by recurrent, appropriate ICD therapies; antitachycardia pacing (ATP) and/or shocks; within a 24-hour period. Some authors defi ne ES as three or more VT/VF episodes separated by at least 5 minutes of sinus rhythm. ICD shocks have signifi cant adverse effects, and available evidence indicates that patients experiencing ES have poorer outcomes. Potential triggers include changes in or non-adherence to medication, worsening heart failure, early postoperative states, emotional stress, alcohol excess, electrolyte imbalances, myocardial ischemia, and less common factors such as fever. However, many ES episodes occur without any identifi able cause.

Objectives: This study aimed to evaluate clinical predictors of appropriate electrical storm in patients with ICDs.

Patients and methods: This single-center, retrospective, observational case-control study was conducted at Ibn-Albitar Specialist Center for Cardiac Surgery from April 1, 2016 to January 1, 2017. Twenty-fi ve consecutive ICD patients admitted with appropriate electrical storm were included as the case group and compared with 25 ICD recipients without ES who attended the center for routine programming and follow-up.

Results: A total of 50 ICD patients were analyzed: 25 with ES (cases) and 25 without ES (controls). The mean ages of the case and control groups were 54 ± 12.09 years and 54.8 ± 12.19 years, respectively. Males constituted 84% of the case group and 40% of the control group. Hypertension was present in 56% of cases and 36% of controls, and diabetes was present in 36% of both groups. Ischemic heart disease was more prevalent among cases (80%) than controls (44%). Left ventricular ejection fraction (LVEF) < 40% was found in 80% of cases compared with 44% of controls. Recent heart failure decompensation (within 1 month) occurred in 56% of cases and only 8% of controls.
Regarding ICD indication, secondary prevention accounted for 80% of cases and 84% of controls. ICD-VR devices were more common in cases (84%) than in controls (44%), while ICD-DR devices were less frequent in cases (16%) versus controls (56%). Systolic heart failure was present in 80% of both groups. Other etiologies included HOCM (2 cases/2 controls), short QT syndrome (2 cases/2 controls), and Noonan syndrome (1 case/1 control). Obesity (BMI > 30) was more prevalent in cases (68%) than in controls (16%). Fever > 38 °C at the time of ES was documented in 28% of cases, with none reported in controls. Current smoking was more common among cases (56%) than controls (40%). Heavy alcohol use occurred in 4% of both groups. Thyroid function was normal across all subjects. Hypokalemia (< 3.5 mmol/L) was present in 64% of cases and 24% of controls, while low magnesium (< 1.6 mg/dL) was found in 64% of cases versus 24% of controls. No early cardiac or non-cardiac surgical interventions had occurred within 6 months in either group.

Conclusion: Electrical storm is a relatively common complication that may occur at any point after ICD implantation and may recur. The study identifi ed several predictors of ES, including reduced LVEF, ICD implantation for secondary prevention, electrolyte disturbances, and absence of amiodarone or ACE-inhibitor therapy.

Keywords: ACE-inhibitors, Amiodarone, Electrical storm, Electrolyte disturbances, ICD implantation

Received: February 15, 2025; Revised: December 4, 2025; Accepted: December 11, 2025; Prepublished online: June 2, 2012; Published: May 20, 2026  Show citation