Cardiovascular Magnetic Resonance-based Tissue Characteristics and Clinical Outcomes in Apical Hypertrophic Cardiomyopathy.

This study aimed to characterize cardiovascular magnetic resonance (CMR) tissue biomarkers in individuals with apical HCM (ApHCM) and assess their association with clinical outcomes. Firstly, CMR imaging-derived tissue characterization parameters, including T1 and T2 relaxation times, Extracellular volume (ECV), and extent of late gadolinium enhancement (LGE), was compared between patients with ApHCM and control patients. Secondly, composite outcome defined as non-sustained ventricular tachycardia detected on holter monitoring, implantation of an implantable cardioverter defibrillator (ICD), or hospitalization for heart failure were assessed amongst those with ApHCM. The study included 91 participants: 76 with ApHCM and 15 matched controls. Compared with controls, patients with ApHCM had higher apical T1 values (1057.2 ± 33.73 vs 1005.53±25.5 msec; p < 0.001), T2 apical values (53.44 ± 2.97 msec vs 48.26 ± 2.99 msec, p < 0.001), and apical ECV fraction (31.96 ± 2.61% vs 26.47 ± 1.32%, p < 0.001). Among ApHCM patients without LGE (n = 38), increased apical T1, T2, and ECV values were identified in 86.5%, 75.8%, and 91.4% of cases, respectively. T2 maximal value above the 50th percentile was significantly associated with the combined endpoint (AdjOR 3.75, 95% CI: 1.10-15.08, p = 0.043), as well as the presence of LGE (AdjOR 8.31, 95% CI: 2.04-56.38, p = 0.009). In conclusion, in ApHCM, T1, T2, and ECV values were increased in the apical segments, even in the absence of LGE. Increased T2 values and the presence of LGE were significantly associated with clinical outcomes, suggesting that these imaging markers may contribute to risk stratification these patients.