Sudden cardiac death risk stratification in patients with a preserved or mildly reduced ejection fraction: role of cardiac magnetic resonance and electrophysiological study

Funding Acknowledgements Type of funding sources: None. BACKGROUND Patients presenting with syncope of suspected arrhythmogenic origin or symptomatic documented non sustained ventricular tachycardia (NSVT) may represent a population with higher risk for sudden cardiac death (SCD). However today there are still no defined criteria to stratify the risk of SCD in this population. PURPOSE To assess the prognostic value of magnetic resonance (MRI) and electrophysiological study (EPS) in the risk stratification for SCD of patients with a preserved or mildly-reduced ejection fraction (EF) that may benefit from implantable cardiac defibrillator (ICD) therapy. METHODS We selected ischemic and non-ischemic patients with a preserved or mildly-reduced ejection fraction who came to our attention either after a probably arrhythmogenic syncopal event or a documented NSVT between 12/2018 and 09/2020. Patients with other ICD indications following current guideline-criteria were excluded (id est Brugada syndrome, Long QT and hypertrophic cardiomyopathy). All patients underwent an echocardiography, a coronary angiography, and an MRI with gadolinium, those among them with a positive LGE also underwent an induction EPS. Non inducible patients were followed-up clinically or with an implantable event-recorder, while inducible patients received an ICD. RESULTS In our observational study seventeen patients with preserved or only mildly-reduced EF were enrolled (13 males and 5 females; mean age 68 years). Among these patients, nine were identified with an underlying myocardial scar with positive Late-Gadolinium-Enhancement (LGE) in MRI. Based on the clinical orientation and the MRI LGE pattern patients were divided in ischemic group (5 patients) and non-ischemic group (4 patients). All 9 patients underwent an induction EPS. Three of them, 2 with non-ischemic and 1 with an ischemic pattern, demonstrated a reproducible inducibility of a sustained ventricular tachycardia or ventricular fibrillation and were implanted with an ICD. During our follow-up two of the three patients had an adequate shock within a year from the ICD implantation. Among the 6 patients with negative induction EPS there were no clinical events in the follow up, except one death for unknown causes. CONCLUSION Our preliminary results demonstrated that in patients with ischemic or non ischemic cardiopathy with preserved or mildly reduced EF, a positive MRI LGE pattern and the inducibility of ventricular arrhythmias during induction EPS identify a population at higher risk for clinical recurrence of ventricular arryhthmic events. Further investigation is needed to validate this combined diagnostic strategy as new SCD prevention tool.