Myocardial Fibrosis Predicts Ventricular Arrhythmias and Sudden Death After Cardiac Electronic Device Implantation.

BACKGROUND Increasing evidence supports a link between myocardial fibrosis (MF) and ventricular arrhythmias. OBJECTIVES The purpose of this study was to determine whether presence of myocardial fibrosis on visual assessment (MF) and gray zone fibrosis (GZF) mass predicts sudden cardiac death (SCD) and ventricular fibrillation/sustained ventricular tachycardia after cardiac implantable electronic device (CIED) implantation. METHODS In this prospective study, total fibrosis and GZF mass, quantified using cardiovascular magnetic resonance, was assessed in relation to the primary endpoint of SCD and the secondary, arrhythmic endpoint of SCD or ventricular arrhythmias after CIED implantation. RESULTS Among 700 patients (age 68.0 ± 12.0 years), 27 (3.85%) experienced a SCD and 121 (17.3%) met the arrhythmic endpoint over median 6.93 years (IQR: 5.82-9.32 years). MF predicted SCD (HR: 26.3; 95% CI: 3.7-3,337; negative predictive value: 100%). In competing risk analyses, MF also predicted the arrhythmic endpoint (subdistribution HR: 19.9; 95% CI: 6.4-61.9; negative predictive value: 98.6%). Compared with no MF, a GZF mass measured with the 5SD method (GZF) >17 g was associated with highest risk of SCD (HR: 44.6; 95% CI: 6.12-5,685) and the arrhythmic endpoint (subdistribution HR: 30.3; 95% CI: 9.6-95.8). Adding GZF mass to MF led to reclassification of 39% for SCD and 50.2% for the arrhythmic endpoint. In contrast, LVEF did not predict either endpoint. CONCLUSIONS In CIED recipients, MF excluded patients at risk of SCD and virtually excluded ventricular arrhythmias. Quantified GZF mass added predictive value in relation to SCD and the arrhythmic endpoint