Evaluation of arrhythmic events in 24-hour rhythm monitoring of patients with pulmonary hypertension

ABSTRACT Evaluation of Arrhythmic Events in 24-Hour Rhythm Monitoring of Patients with Pulmonary Hypertension Objective: Pulmonary hypertension (PH) leads to pressure overload and remodeling of the right heart and, although often clinically silent, may result in significant arrhythmias. In PH, functional capacity, biomarkers, and hemodynamic parameters are used for risk stratification; however, the prognostic value of long-term rhythm monitoring remains uncertain. Limited evidence suggests that autonomic imbalance and ectopic activity may be associated with hemodynamic burden. This study aimed to evaluate the relationship between arrhythmic burden and heart rate variability (HRV) derived from 24-hour Holter monitoring and established prognostic parameters. Material and method: This single-center, observational and cross-sectional study included 64 patients diagnosed with non-group 2 PH who underwent 24-hour Holter ECG monitoring at Çukurova University Faculty of Medicine. Clinical data including WHO functional class, REVEAL Lite 2 risk score, cardiac biomarkers, echocardiographic measurements, right heart catheterization findings, and HRV indices were systematically collected and analyzed. Results: Supraventricular arrhythmias were detected in 34.4% of patients, with atrial fibrillation (12.5%) and atrial flutter (9.4%) being the most common. Non-sustained ventricular tachycardia (nsVT) occurred in 10.9% of patients. Arrhythmia prevalence was similar across WHO PH subgroups (all p>0.05). Patients with atrial fibrillation had larger right atrial and pulmonary artery diameters, and more impaired right ventricular function. Those with nsVT had higher BNP levels (1,316 vs 230 pg/ml, p=0.041) and shorter 6-minute walk distance (160 m vs 390 m, p=0.005). Overall autonomic suppression was observed (mean SDNN: 93 ± 8 ms; LF/HF: 1.83), with SDNN significantly lower in high-risk groups (97 ms vs 89 ms, p=0.017). HRV showed negative correlation with mean pulmonary artery pressure, pulmonary vascular resistance, and RV diameter, and positive correlation with TAPSE and RVOT acceleration time. Conclusion: Clinically relevant arrhythmias are common and HRV is markedly reduced in non-group 2 PH patients. Arrhythmic burden and autonomic dysregulation appear to reflect hemodynamic severity and right heart remodeling. We suggest that 24-hour Holter monitoring may contribute to multidimensional risk stratification and facilitate early detection of clinical deterioration. Multicenter prospective studies are warranted to validate these findings. Keywords: Pulmonary hypertension; 24-hour Holter; arrhythmia; heart rate variability; risk stratification.