Greyzone myocardial fibrosis and ventricular arrhythmias in patients with a left ventricular ejection fraction >35%

AIMS: To determine whether myocardial fibrosis and greyzone fibrosis (GZF) on cardiovascular magnetic resonance (CMR) is associated with ventricular arrhythmias in patients with coronary artery disease (CAD) and a left ventricular ejection fraction (LVEF) >35%. METHODS AND RESULTS: In this retrospective study of CAD patients, GZF mass using the 3SD method (GZF(3SD)) and total fibrosis mass using the 2SD method (TF(2SD)) on CMR were assessed in relation to the primary, combined endpoint of sudden cardiac death, ventricular tachycardia, ventricular fibrillation, or resuscitated cardiac arrest. Among 701 patients [age: 65.8 ± 12.3 years (mean ± SD)], 28 (3.99%) patients met the primary endpoint over 5.91 years (median; interquartile range 4.42–7.64). In competing risks analysis, a GZF(3SD) mass ≥5.0 g was strongly associated with the primary endpoint [subdistribution hazard ratio (sHR): 17.4 (95% confidence interval, CI 6.64–45.5); area under receiver operator characteristic curve (AUC): 0.85, P < 0.001]. A weaker association was observed for TF(2SD) mass ≥23 g [sHR 10.4 (95% CI 4.22–25.8); AUC: 0.80, P < 0.001]. The range of sHRs for GZF(3SD) mass (1–527) was wider than for TF(2SD) mass (1–37.6). CONCLUSIONS: In CAD patients with an LVEF >35%, GZF(3SD) mass was strongly associated with the arrhythmic endpoint. These findings hold promise for its use in identifying patients with CAD and an LVEF >35% at risk of arrhythmic events.