Ring-type PPG sensor for the detection of ventricular arrhythmias

Background Ventricular arrhythmias (VA) are most frequently the onset of sudden cardiac death and early detection is key for survival. Limited studies suggest wrist worn photoplethysmography (PPG) sensors can detect VA. Ring-type wearable PPG sensors may be more accurate, however they have not yet been investigated. Purpose We aim to show the sensitivity of a ring-type wearable PPG sensor to detect induced VA. Methods Patients undergoing a procedure involving VA induction were included. The ring-type wearable PPG sensor was positioned on the finger of the patient during the procedure and PPG and reference ECG data were collected (Figure 1). A loss of cardiac output (CO) was defined as a flatline, or a decrease in amplitude ≥50%. Sensitivity was calculated using a contingency table. Bland-Altman analysis and intraclass correlation coefficients (ICC) were used to assess the agreement between PPG- and ECG-derived arrhythmia durations. Results Thirty-seven patients were enrolled, of whom 25 were included: defibrillation threshold testing (n=16), ventricular tachycardia (VT) ablation (n=8) and electrophysiological study (n=1). A total of 67 VA, of which 27 ventricular fibrillation (VF) and 40 VT episodes, were recorded. A loss of CO was observed on the tachograms of all VF episodes and in 36 (90%) VT episodes (Figure 2). The sensitivity was 94% (100% for VF, 90% for VT). Mean difference in VA duration was 0.1 (95% Limits of Agreement -1.4 – 1.7) seconds, with an ICC of 0.998 (95% CI: 0.997 – 0.999), indicating excellent agreement. Conclusion This study suggests that a ring-type wearable PPG sensor can detect, with high sensitivity, changes in arterial pulse flow during induced VA.