Myocardial fibrosis as a key determinant of left ventricular remodeling in idiopathic dilated cardiomyopathy: a contrast-enhanced cardiovascular magnetic study.

BACKGROUND: In idiopathic dilated cardiomyopathy, there are scarce data on the influence of late gadolinium enhancement (LGE) assessed by cardiovascular magnetic resonance on left ventricular (LV) remodeling.

METHODS AND RESULTS: Fifty-eight consecutive patients with idiopathic dilated cardiomyopathy underwent baseline clinical, biohumoral, and instrumental workup. Medical therapy was optimized after study enrollment. Cardiovascular magnetic resonance was used to assess ventricular volumes, function, and LGE extent at baseline and 24-month follow-up. LV reverse remodeling (RR) was defined as an increase in LV ejection fraction ≥10 U, combined with a decrease in LV end-diastolic volume ≥10% at follow-up. ΔLGE extent was the difference in LGE extent between follow-up and baseline. LV-RR was observed in 22 patients (38%). Multivariate regression analysis showed that the absence of LGE at baseline cardiovascular magnetic resonance was a strong predictor of LV-RR (odds ratio, 10.857 [95% confidence interval, 1.844-63.911]; P=0.008) after correction for age, heart rate, New York Heart Association class, LV volumes, and LV and right ventricular ejection fractions. All patients with baseline LGE (n=26; 45%) demonstrated LGE at follow-up, and no patient without baseline LGE developed LGE at follow-up. In LGE-positive patients, there was an increase in LGE extent over time (P=0.034), which was inversely related to LV ejection fraction variation (Spearman ρ, -0.440; P=0.041). Five patients showed an increase in LGE extent >75th percentile of ΔLGE extent, and among these none experienced LV-RR and 4 had a decrease in LV ejection fraction ≥10 U at follow-up.

CONCLUSIONS: In patients with idiopathic dilated cardiomyopathy, the absence of LGE at baseline is a strong independent predictor of LV-RR at 2-year follow-up, irrespective of the initial clinical status and the severity of ventricular dilatation and dysfunction. The increase in LGE extent during follow-up was associated with progressive LV dysfunction.