Backgrounds: Lack of left ventricular reverse remodeling (LVRR) is a marker of a worse prognosis in patient with idiopathic dilated cardiomyopathy (IDC). Native myocardial T1 in cardiac magnetic resonance imaging (CMR) has emerged as a potential for the quantitative assessment of diffuse myocardial tissue injury. However, the relationship between Native T1 and LVRR after medical therapy in IDC remains unclear.
Methods: Fifty-six patients with stable IDC (37 men, 50.5±11 years old) underwent CMR imaging at 3T between 2013 and 2015. Shortened modified Look-Locker inversion recovery T1 maps were generated from 3 short-axis images in each patient. Myocardial native T1 values were calculated as the average of all segments from the images. All patients were treated with angiotensin converting enzyme inhibitors or angiotensin receptor blockers, and β-blockers. LVRR was defined as an absolute increase in left ventricular ejection fraction (LVEF) of ≥10% and the final value of LVEF of >35%, accompanied by a decrease in LV end-diastolic dimension ≥10% at 12 months of follow-up. In addition, cardiac troponin-T (TnT) levels, known as myocardial marker of injury, were measured at diagnosis.
Results: LVRR was observed in 30 individuals (54%). Native T1 were significantly higher in patients who lack LVRR than those with LVRR (1373±76ms vs 1292±47ms, p<0.001). The cutoff level of Native T1 was determined to be 1328ms by ROC analysis, which maximized the sensitivity and the specificity for the prediction of LVRR (0.800 and 0.693, respectively, AUC=0.819). A composite endpoint of mortality, heart failure hospitalization, and referred for LV assist device or cardiac resynchronization therapy consisted more likely in patients with native T1 ≥1328ms (Hazard ratio=11.4, P=0.002). Furthermore, the mean cardiac TnT value were 0.0159±0.012ng/mL, and native T1 was positively correlated with serum levels of high-sensitivity cardiac troponin T (p<0.0001, R=0.514).
Conclusions: Higher myocardial native T1 time was associated with lack of LVRR and worse prognosis, suggesting a possible prognostic marker in IDC. Positive correlation with serum cardiac troponin-T level indicates that myocardial native T1 time is reflected by the degree of myocardial injury.