Arrhythmic major adverse cardiac events (MACE) and heart failure (HF) are potential complications in patients with mitochondrial disorders. For a study, researchers sought to calculate the risk of HF and arrhythmic MACE.

In 600 adult patients from a multicenter registry with genetically proven mitochondrial disorders, they used Cox regression to evaluate the incidence and look for predictors of HF and arrhythmic MACE.

The HF objective was attained in 29 patients (4.9%) after a median follow-up period of 6.67 years. It included 19 hospitalizations for nonterminal HF, two heart transplantations, and 8 HF-related deaths. Thirty more patients (5.1%) made it to the arrhythmic MACE, including 21 with type II or third-degree atrioventricular blocks, 4 with sinus node dysfunction, and 5, with sudden cardiac deaths. The left ventricular (LV) hypertrophy (HR: 2.6; 95% CI: 1.1-5.8), conduction abnormalities (HR: 3.0; 95% CI: 1.3-6.9), LV ejection fraction less than 50% (HR: 10.2; 95% CI: 4.6-22.3), m.3243A>G variant (HR: 4.3; 95% CI: 1.8-10.1), and premature ventricular beats (HR: 4.1; 95% CI: 1.7-9.9) were all predictors of HF. Single, large-scale mtDNA deletions (HR: 4.3; 95% CI: 1.7-10.4), conduction abnormalities (HR: 6.8; 95% CI: 3.0-15.4), and LV ejection fraction less than 50% (HR: 2.7; 95% CI: 1.1-7.1) were independent predictors for arrhythmia. For the HF and arrhythmic MACE, the C-indices of the Cox regression models were 0.91 (95% CI: 0.88-0.95) and 0.80 (95% CI: 0.70-0.90), respectively.

Using genetic variant type and straightforward cardiac evaluations, they created the first prediction models for HF and arrhythmic MACE in individuals with mitochondrial disorders.