Predictive value of ambulatory ECG monitoring for malignant arrhythmic events in genetic dilated cardiomyopathy

AIMS: Evaluate the prognostic significance of arrhythmias and conduction disorders on ambulatory ECG in recently diagnosed genetic vs. non-genetic dilated cardiomyopathy (DCM). OBJECTIVE: To compare the prevalence of abnormalities on ambulatory ECG monitoring between genetic and non-genetic DCM patients and evaluate the predictive value for malignant ventricular adverse events (MVAEs). METHODS AND RESULTS: Clinical and ambulatory ECG data were collected from 354 genotyped DCM probands, with a median follow-up of 8 years (IQR: 5-9 years). The malignant ventricular adverse event was defined as ventricular fibrillation, sustained ventricular tachycardia, anti-tachy pacing, appropriate device therapy, or sudden cardiac death. C-statistics assessed the predictive performance of the regression models. In total, 123 (35%) patients carried a (likely) pathogenic variant. Abnormalities on ambulatory ECG were more frequent in genetic DCM patients (80%) compared to non-genetic DCM (67%; P = 0.013). Permanent atrial fibrillation (perAF), paroxysmal supraventricular tachycardia (parox-SVT), and non-sustained ventricular tachycardia (NSVT) were more frequent in genetic DCM patients (P = 0.041, <0.001, and <0.001). Structural cardiac parameters showed minimal group differences. Using Cox proportional hazard analyses to predict MVAE, ambulatory ECG variables (perAF, AV-block, NSVT, >500 premature ventricular complexes (PVCs)/24 h) had an area under the curve (AUC) of 0.768 in genetic and 0.628 in non-genetic DCM patients (P = 0.044). The premature ventricular complex burden was only predictive for MVAE in genetic DCM. Adding clinical variables provided little incremental predictive value for genetic vs. non-genetic DCM (AUC Δ+0.004 vs. Δ+0.150, respectively). CONCLUSION: Ambulatory ECG monitoring abnormalities are prevalent in genetic DCM patients. In contrast to non-genetic DCM patients, ambulatory ECG parameters have an important predictive value to determine the risk of MVAE in genetic DCM patients.