Diagnostic work-up and clinical characteristics in out-of-hospital cardiac arrest survivors with ICD implantation: a prospective Danish study
D M Stavnem, P Bhardwaj, S Lykke, C J Hansen, F Folke, J Tfelt-Hansen, B G WinkelAbstract
Background
Identifying a cause following sudden cardiac arrest (SCA) is essential for post-arrest management, risk stratification and family evaluation. Yet systematic diagnostic work-up following SCA was only recently implemented in major guidelines. We present the results of guideline-driven diagnostic evaluation in a prospective SCA population.
Method
In this prospective cohort study, we included all out-of-hospital cardiac arrest (OHCA)-survivors with a clinical indication for implantable cardioverter-defibrillator (ICD) implantation in the capital region in Denmark from February 2019 to July 2025. All patients underwent a systematic staged diagnostic work-up including electrocardiograms (ECG), echocardiography, cardiac imaging, and provocative testing. This algorithm was later adopted to fit the 2022 ESC guidelines for ventricular arrhythmias and sudden cardiac death.
Results
We included 320 patients (75% male sex, mean age 57 years), of whom 65% had known cardiac disease prior to arrest. The majority underwent echocardiography (319, 99.4%) and coronary visualization (319, 99.4% - coronary angiogram in 278 (87%) and cardiac computed tomography angiogram in 41 (13%)). Cardiac magnetic resonance imaging was performed in 214 (67%) patients. Specialized (ECG) examinations, e.g. elevated leads and brisk standing ECG were performed in 137 (59%) patients. Exercise testing was performed in 120 (37%) patients and sodium channel blocker testing in 56 (17%). A cause of arrest was identified in 257 (80%) patients, of which 110 (34%) were caused by ischemic heart disease. Other prevalent causes were arrhythmogenic cardiomyopathy (n=60, 18%) and dilated cardiomyopathy (n=39, 13%). Despite extensive work-up, 64 (20%) patients remained unexplained and were categorized as idiopathic ventricular fibrillation (IVF). The percentage of IVF was notably higher in younger patients, accounting for 46% of survivors under 50, compared to only 10% in those aged 50 or older.
Conclusion
By employing a systematic staged diagnostic algorithm following OHCA, we identified a definite cause of arrest in 80% of OHCA survivors with a clinical indication for ICD implantation. This evaluation confirms that systematic diagnostic algorithms for OHCA align with evidence-based recommendations