Prognostic Significance of Heart Rate Turbulence Parameters in Patients with Noncompaction Cardiomyopathy

Noncompaction cardiomyopathy (NC) is a rare congenital heart disease characterized by progressive heart failure and life-threatening arrhythmias. Heart rate turbulence (HRT) has been defined as a noninvasive prognostic method to reveal the cardiac death risk in high-risk patients.

We aimed to assess the cardiac autonomic functions and their relations to the mortality in NC patients.

A total of 60 NC patients and 70 healthy controls were included in this study. All participants underwent 24-h Holter recording to assess the HRT parameters, included turbulence onset (TO), turbulence slope (TS), standard deviation of NN intervals of all normal beats (SDNN) and mean RR interval.

NC patients had higher levels of TO than the control group (0.43 ± 4.66% vs. -1.82 ± 2.19%, p = 0.024), but the TS levels of NC patients were lower than those of the control group (3.43 ± 3.28 vs. 4.94 ± 2.86 ms/RR, p = 0.024). Thirteen patients died during follow-up (mean 83.3 ± 32.5 months). TS was the strongest univariate mortality predictor (hazard ratio 10.01 [95% CI 2.22-42.52]; p = 0.004) in univariate Cox regression analysis. In multivariate analysis, LVEF ≤0.40 and TS ≤2.5 ms/RR interval were the only independent predictors of mortality (hazard ratio 5.29; p = 0.004, hazard ratio 13.45; p = 0.001, respectively).

Patients with NC showed abnormal HRV and HRT parameters when compared to healthy subjects. Furthermore, impaired HRT reaction in NC is an independent predictor of mortality.