Is heart rate variability a prognostic factor of supraventricular arrhythmias in adults with congenital heart disease?

Objective:
As the life expectancy in adults with congenital heart defects (ACHD) is rising, supraventricular tachycardia (SVT) is becoming increasingly significant, potentially causing progressive heart failure or even death. We aimed to evaluate the value of different parameters of heart rate variability for risk assessment.

Methods:
We prospectively followed a cohort of 291 patients (mean age at inclusion 35.4±11.04 years, 57%male, mean observation time 48.4±16.6 months, disease complexity: great 59.7%, moderate 24.8%, mild 15.5%). Cox proportional survival analysis was used to assess the relationship between SVT and parameters of heart rate variability (SDNN, Triangularindex, SymIndex) derived from a 20-minute ECG analysis at rest, biomarkers, heart disease severity and NYHA functional class. Receiver operative characteristics were calculated from independent predictors. Youden Index was used for the calculation of optimal cut-off points.

Results:
In the total cohort 35 (12%) patients experienced SVT with 21 cases of atrial fibrillation; 6 cases of atrial flutter and 8 cases of atrial tachycardia. Significant single predictors of SVT were included in the multivariate regression analysis: the heart rate variability parameter SymIndex, Triangularindex, a history of SVT, sinus node dysfunction, albumin, NT-proBNP, epicardial adipose tissue, beta-blocker intake, NYHA-class and disease complexity.

In this model SymIndex (HR: 0.73 [CI:0.54-0.98]), disease complexity (HR:0.44 [CI:0.20-0.98]) and a history of SVT (HR:3.13[CI:1.47-6-67]) remained independent predictors, even when adjusted for age and sex.

In patients with a history of SVT, those with a higher SymIndex survived significantly longer without the recurrence of SVT (56.4 vs. 41.6months [p=0.016]).

Conclusion:
HRV at rest may be helpful to identify patients at risk of future SVT. This information might influence medical and interventional treatment options. Further prospective studies are needed to confirm this hypothesis.