Heart rate variability reduction as a non-ivasive predictor of ventricular tachyarrythmias in patients with coronary artery disease

Highlights. The implantation of cardioverter-defibrillator is the most effective method for preventing sudden cardiac death. However, almost 25% patients have normally functioning CD at the 5-years follow-up. This has necessitated the search for new non-invasive diagnostic methods for detecting patients at high risk of ventricular tachyarrhythmias. Aim. To evaluate whether the estimated heart rate variability may be used as a predictor for ventricular arrhythmias (VTA) in patients with coronary artery disease. Methods . 51 patients (mean age of 65.4±8.4 year; 41 male patients (80,3%)) with coronary artery disease (CAD) and indications for cardioverter-defibrillator (ICD) implantation were included to the study. The 6-minute walk distance, echocardiography, heart rate variability (HRV) were assessed and compared between the groups. The statistical analysis was performed using the Statistica 10.0, StatSoft (USA) and MedCalc statistical software (USA). Results . 43 (84.3%) patients with VTA within the 18-months follow-up were assigned to Group 1, and 8 (15.7%) patients without VTA during the 18-month follow-up were assigned to Group 2. The univariate ROC-analysis showed that a reduction in the average NN interval less than 1130 ms (p = 0.0282), root mean square of successive differences less than 18 ms (p = 0.0037) and high frequency spectral component less than 770 ms (p = 0.0001) contributed to the onset of of VTA. Multivariate ROC-analysis demonstrated that the end-diastolic index (p = 0.0185) and standard deviation of NN interval (p = 0.0370) were independent predictors of VTA. An increase of the VTA predictive index (calculated according to the presented predictive model) by >0.5613 suggested the onset of VTA (AUC = 0.927; p = 0.0001). Conclusion . Reduced HRV may be a non-invasive VTA predictor in patients with CAD. The combined use of echocardiography and HRV analysis allows identifying a group of patients with high risk of sudden cardiac death.