Prognostic significance of myocardial extracellular volume fraction in nonischaemic dilated cardiomyopathy

Aims In nonischaemic dilated cardiomyopathy (NICM), replacement myocardial fibrosis as detected by late gadolinium enhancement (LGE) at cardiovascular magnetic resonance (CMR) is associated with poor prognosis. We investigated the as-yet unexplored prognostic significance of interstitial fibrosis in NICM, using T1-mapping CMR. Methods Eighty-nine NICM patients (63 men, age 59W14 years) with left ventricular systolic dysfunction (ejection fraction 41W13%) underwent comprehensive clinical and CMR evaluation, with extracellular volume fraction (ECV) estimation from pre and postcontrast T1 mapping. Fifteen healthy individuals (11 men, mean age 52W11 years) were used as controls. The end-point was a composite of cardiovascular death, hospitalization for heart failure and appropriate defibrillator intervention. Results Myocardial ECV was higher in NICM patients (0.31W0.05) than controls (0.25W0.04, P<0.01). In NICM patients, myocardial ECV correlated with left ventricular ejection fraction (R2 U0.13), LGE extent (R2 U0.17), Doppler E/E0 (R2U0.17) and ventricular tachycardias (R2 U0.21) at 24-h ECG monitoring (P<0.05 for all). During a median follow-up of 24 months (interquartile range 12-42 months), 12 events occurred and higher myocardium ECV was independently associated with the occurrence of the composite end-point (P<0.01). Conclusion In NICM patients, myocardial ECV was increased compared with normal individuals, likely reflecting extracellular matrix remodelling and collagen deposition, and resulted an independent prognostic predictor beyond all other conventional clinical, electrocardiographic and echocardiographic parameters.