Differentiation of NYHA III and IV Heart Failure with Infrared Thermal Imaging.

Background: In advanced heart failure patients, limited exercise capacity often prevents significant increases in core temperature. Due to reduced muscle mass and minimal blood flow in inactive muscles, their limb temperatures tend to be lower. This study investigates whether core-hand temperature difference can serve as a distinguishing criterion between New York Heart Association (NYHA) Class III and IV heart failure. Methods: This study included 80 patients with NYHA Class IV (median age: 68 years) and 82 with NYHA Class III (median age: 65 years) heart failure with reduced ejection fraction. Core body temperature was measured using an infrared thermometer, while hand temperature was recorded with a forward looking infrared C5 thermal camera after a 15-minute acclimatization at room temperature. Results: The core-mean hand temperature difference (Tc-Mht) was 8.7 °C ± 1.5 °C in the Class IV group and 7.1 °C ± 1.7 °C in the Class III group (p < 0.001). The difference in hand temperature (highest-lowest) was 3 °C (2-4 °C) in the Class IV group and 1 °C (0-2 °C) in the Class III group (p < 0.001). Conclusions: A Tc-Mht > 7.7 °C showed 76% sensitivity (95% confidence interval: 66-84%) for detecting NYHA Class IV in thermoneutral environments. Tc-Mht may serve as a prognostic marker in heart failure patients.