RR interval analysis based on a newly developed PC program as a predictor of interventions in implantable cardioverter-defibrillator patients

BACKGROUND: Prediction of sudden cardiac death remains a significant challenge. There is some evidence that ventricular ectopic activity could be regarded as a predictive marker. OBJECTIVES: We carried out an analysis to explore whether premature ventricular complexes (PVCs) are a risk factor in implantable cardioverter-defibrillator (ICD) interventions. MATERIAL AND METHODS: The study method was a RR interval series analysis (n = 184) of arrhythmic events and controls from the ICD. Study group consisted of patients with a mean age of 55 ±27 years; 74% of them were male, 85% were secondary prevention patients, 62% had coronary artery disease (CAD), 15% hypertropic cardiomyopathy (HCM), 15% dilated cardiomyopathy (DCM), and 8% diseases of other etiology. The mean follow-up time was 64 months (range: 3-126 months). The study population was divide into patients with at least 1 appropriate intervention ventricular tachycardia/ventricular fibrillation (VT/VF) (group A, n = 101) and controls without interventions (group B, n = 83). The number of PVC/4000 RR cycles, the shortest coupling intervals between a PVC and preceding R as well as the number of PVCs of very short (180-220 ms), short (220-280 ms) and different cycle lengths (CL) as well as the incidence of short-long-short (SLS) sequences were compared. RESULTS: The number of PVCs/4000 RR cycles was significantly higher in group A (263 ±32 compared to 43 ±17, p < 0.0001). The mean shortest PVC CL was significantly shorter in group A (320 ±13 compared to 400 ±38, p = 0.029). The number of PVCs with a very short CL was 1 ±0.4 compared to 0.1 ±0.1 (p = 0.028). The number of PVCs with a short CL was 5 ±1.2 compared to 0.6 ±0.4 (p = 0.0007) in groups A and B, respectively. The incidence of SLS sequences was significantly higher in group A than in group B (67 (94% of patients) and 4 (33% of patients) respectively (p < 0.0001)). CONCLUSIONS: Significant differences were found in the characteristics of PVCs and SLS sequences between patients with appropriate ICD interventions and controls. A newly developed basic computer program called PCRR was applied for RR interval analysis. This simple method could be a predictor of PVC burden and life-threatening arrhythmias in different populations.