Accuracy and clinical utility of heart rate variability derived from a wearable heart rate monitor in patients undergoing major abdominal surgery.

Low heart rate variability (HRV) can potentially identify patients at risk of intraoperative hypotension. However, it is unclear whether cheaper, readily accessible consumer heart rate (HR) monitors can provide similar utility to clinical Holter electrocardiograph (ECG) monitors. The objectives of this study were (1) to assess the validity of using the Polar H10 HR monitor as an alternative to a clinical Holter ECG and (2) to test total power (TP) as a predictor of intraoperative hypotension. The primary outcome was the level of agreement between Polar H10 and Holter ECG. Twenty-three patients undergoing major abdominal surgery with general anesthesia had 5-minute HR recordings taken concurrently with both devices during a pre-anesthetic consultation. Agreement between Polar H10 and Holter ECG was compared via Bland-Altman analysis and Lin's Concordance Correlation Coefficient. Patients were divided into groups based on TP <  500 m s 2 and TP >  500 m s 2 . Intraoperative hypotension was defined as MAP < 60 mmHg, systolic blood pressure < 80 mmHg, or 35% decrease in MAP from baseline. There was substantial agreement between Polar H10 and Holter ECG for average R-R interval, TP and other HRV indices. Reduced TP (< 500  ms 2 ) had a high sensitivity (80%) and specificity (100%) in predicting intraoperative hypotension. Patients with reduced TP were significantly more likely to require vasoactive drugs to maintain blood pressure.The substantial agreement between Polar H10 and Holter ECG may justify its use clinically. The use of preoperative recordings of HRV has the potential to become part of routine preoperative assessment as a useful screening tool to predict hemodynamic instability in patients undergoing general anesthesia.