Titin-truncating variants are associated with heart failure events in patients with left ventricular non-compaction cardiomyopathy

Background Titin-truncating variants (TTNtv) have been recognized as the most prevalent genetic cause of dilated cardiomyopathy. However, their effects on phenotypes of left ventricular non-compaction cardiomyopathy (LVNC) remain largely unknown. Hypothesis The presence of TTNtv may have an effect on the phenotype of LVNC. Methods TTN was comprehensively screened by targeted sequencing in a cohort of 83 adult patients with LVNC. Baseline and follow-up data of all participants were collected. The primary endpoint was a composite of death and heart transplantation. The secondary endpoint was heart failure (HF) events, a composite of HF-related death, heart transplantation, and HF hospitalization. Results Overall, 13 TTNtv were identified in 13 patients, with 9 TTNtv located in the A-band of titin. There was no significant difference in baseline characteristics between patients with and without TTNtv. During a median follow-up of 4.4 years, no significant difference in death and heart transplantation between the two groups was observed. However, more HF events occurred in TTNtv carriers than in non-carriers (P = 0.006). Multivariable analyses showed that TTNtv were associated with an increased risk of HF events independent of sex, age, and baseline cardiac function (hazard ratio: 3.25, 95% confidence interval: 1.50-7.01, P = 0.003). Sensitivity analysis excluding non-A-band TTNtv yielded similar results, but with less strength. Conclusions The presence of TTNtv may be a genetic modifier of LVNC and confer a higher risk of HF events among adult patients. Studies of larger cohorts are needed to confirm our findings.