Title:
Baseline cardiac magnetic resonance imaging versus baseline endomyocardial biopsy for the prediction of left ventricular reverse remodeling and prognosis in response to therapy in patients with idiopathic dilated cardiomyopathy.

Abstract:
Endomyocardial biopsy (EMB) and late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR) imaging performed at baseline are both used to evaluate the extent of myocardial fibrosis. However, no study has directly compared the effectiveness of these diagnostic tools in the prediction of left ventricular reverse remodeling (LVRR) and prognosis in response to therapy in patients with idiopathic dilated cardiomyopathy (IDCM). Seventy-five patients with newly diagnosed IDCM who were undergoing optimal therapy were assessed at baseline using LGE-CMR imaging and EMB; the former measured LGE area and the latter measured collagen volume fraction (CVF) as possible predictive indices of LVRR and cardiac event-free survival. Among all the baseline primary candidate factors with P < 0.2 as per univariate analysis, multivariate analysis indicated that only LGE area was an independent predictor of subsequent LVRR (β = 0.44; 95 % confidence interval (CI) 0.87-2.53; P < 0.001), as indicated by decreasing left ventricular end-systolic volume index over the 1-year follow-up. Kaplan-Meier curves indicated significantly lower cardiac event-free survival rates in patients with LGE at baseline than in patients without (P < 0.01). By contrast, there was no significant difference in prognosis between patients with CVF values above (severe fibrosis) and below (mild fibrosis) the median of 4.9 %. Cox proportional hazard analysis showed that LGE area was an independent predictor of subsequent cardiac events (hazard ratio 1.06; 95 % CI 1.02-1.10; P ≤ 0.01). The degree of myocardial fibrosis estimated by baseline LGE-CMR imaging, but not that estimated by baseline EMB, can predict LVRR and cardiac event-free survival in response to therapy in patients with newly diagnosed IDCM.