Abstract
BACKGROUND: Type 2 diabetes mellitus (T2DM) increases the risk of poor long-term outcomes in patients with non-ischemic dilated cardiomyopathy (DCM). However, the prognostic significance of T2DM on late gadolinium enhancement (LGE) patterns and bi-ventricular myocardial strain in non-ischemic DCM remains unclear. Therefore, we aimed to investigate and compare the clinical characteristics, cardiovascular magnetic resonance (CMR) features and outcomes in non-ischemic DCM patients with and without T2DM. METHODS: A total of 423 non-ischemic DCM patients (121 with T2DM and 302 without) who underwent CMR were retrospectively analyzed. Comprehensive clinical evaluations and CMR parameters, including global longitudinal strain (GLS), global radial strain (GRS), and global circumferential strain (GCS) of left ventricular (LV) and right ventricular (RV), as well as LGE mass ratios and patterns, were obtained. Major adverse cardiac events (MACE) during follow-up included cardiovascular death, heart transplantation, heart-failure readmission, and LV assist device implantation for advanced heart failure. Cox regression analysis and Kaplan-Meier analysis assessed the associations between variables and outcomes. RESULTS: DCM patients with T2DM had significantly lower LVGLS {-6.2% [interquartile range (IQR), -7.8% to -4.8%] vs. -7.6% (IQR, -12.1% to -5.4%), P<0.001}, LVGRS [13.8% (IQR, 10.7-19.2%) vs. 16.0% (IQR, 11.3-21.5%), P=0.027], and RVGLS [-10.8% (IQR, -13.2% to -9.0%) vs.-14.7% (IQR, -18.3% to -10.2%), P<0.001]. They also exhibited a higher LGE mass ratio [10.4% (IQR, 2.6-19.0%) vs. 4.0% (IQR, 1.0-9.1%), P<0.001] despite similar LV ejection fraction compared to those without T2DM. Patients with T2DM also showed a greater incidence of mimicking ischemic LGE patterns (33.1% vs. 14.6%, P<0.001), particularly subendocardial LGE (27.3% vs. 10.6%, P<0.001), despite similar overall prevalence of LGE. After a median follow-up of 42 months (IQR, 30-54 months), MACE occurred in 117 patients (28%) for the overall population. Kaplan-Meier analysis indicated that T2DM patients had a significantly elevated risk of MACE compared to non-T2DM individuals. In the multivariate Cox analysis of patients with T2DM, N-terminal pro-B-type natriuretic peptide (NT-proBNP) [hazard ratio (HR): 1.812, 95% confidence interval (CI): 1.276-2.543, P=0.001], hemoglobin A1c (HbA1c) (HR: 1.259, 95% CI: 1.031-1.53, P=0.025), LVGLS (HR: 1.339, 95% CI: 1.128-1.591, P=0.001), and ischemic LGE prevalence (HR: 2.46, 95% CI: 1.361-4.458, P=0.003) were identified as independent predictors of the MACE endpoint. CONCLUSIONS: T2DM adversely affects biventricular myocardial strain, LGE mass ratio, and ischemic LGE prevalence in non-ischemic DCM patients. Combining NT-proBNP, HbA1c, LVGLS, and ischemic LGE prevalence may serve as effective markers for predicting outcomes in T2DM patients.