Long-term Monitoring to Detect Risk of Sudden Cardiac Death in Inherited Arrhythmia Patients

Risk stratification in inherited arrhythmia syndromes is challenging. Implantable cardioverter defibrillators (ICDs) are effective in the prevention of sudden cardiac death but are associated with significant complications. We aimed to determine the value of long-term implantable loop recorder (ILR) monitoring to determine risk factors for arrhythmias in inherited arrhythmia patients.

We conducted a prospective multicentre study between 2015 and 2020 recruiting inherited arrhythmia probands and family members at intermediate arrhythmic risk, with no class 1 indication for ICD implantation. The primary endpoint was the detection by ILR of nonsustained ventricular tachycardia over ≥ 10 consecutive beats. Secondary endpoints included ICD insertion during follow-up, all-cause mortality, and ILR complication rates.

A total of 45 individuals (30 female participants) were enrolled in the study. The most common diagnoses were long-QT syndrome (28%), Brugada syndrome (26%), and arrhythmogenic cardiomyopathy (11%). Following ILR insertion (mean follow-up 633 days; range, 387-969), cardiac symptoms occurred in 19 of 45 patients (42%), 5 of whom had nonsustained ventricular tachycardias (11%), which were symptomatic in 3 individuals. This situation led to ICD implantation based on ILR in 5 of 45 patients (11%). Fifty percent of symptomatic events occurred in ARVC patients. The median time from ILR insertion to ICD implantation was 152 days (interquartile range (25th, 75th percentiles) 55 of 209). No patient experienced sudden cardiac death.

ILRs enable the detection of high-risk arrhythmic features and facilitate selection of ICD candidates in inherited arrhythmia patients with borderline indications.