Heart Rate Variability as a Tell-tale Marker of Pain-related Autonomic Dysfunction in Chronic Pancreatitis

Introduction: – Chronic pain causes an imbalance of autonomic function, often indicated by reductions in parasympathetic heart rate variability (HRV) indices. This study aimed to investigate HRV measures among patients with chronic pancreatitis (CP), and healthy controls (HCs), and the influence of diabetes on these parameters. Methods: – HRV measures, which are time and frequency-derived non-invasive measures of autonomic function, were obtained from the electrocardiography (ECG) recordings. Moreover, deceleration capacity, and periodic repolarization dynamics were assessed as measures of parasympathetic and sympathetic activity. Results: – A total of 141 participants (38 pain-free CP, 53 painful CP, and 50 healthy controls) were analysed. Painful CP patients exhibited more pronounced parasympathetic reductions assessed with the root mean square of successive differences between normal beats (14.5 ms IQR 11.5-22 versus 21.8 ms IQR 17.6-32.4; P=0.01) and high frequency content (118.2 ms² versus 273.4 ms²; P=0.007) in comparison to pain-free CP. Moreover, there was a decreased standard deviation of normal-to-normal interbeat intervals (31.6±18.7 ms versus 39.9±18.5 ms; P=0.04), and low frequency content (158.9 ms² versus 480.4 ms²; P=0.003) indicating altered sympathovagal balance. Furthermore, the mean RR interval was greater in non-diabetic CP patients (830.5±144.2 ms) compared to those with diabetes (770.7±139.4 ms; P=0.05). Conclusions: – Chronic pancreatitis, particularly when painful, is associated with significant autonomic dysregulation, characterized by a pronounced reduction in parasympathetic activity as measured by HRV compared to pain-free patients.