Abstract Body (Do not enter title and authors here): Background: The emerging field of cardiac optogenetics uses pulses of light to stimulate optically-sensitive proteins in the heart, influencing cellular physiology with unprecedented spatiotemporal resolution. Potential benefits may include heart rhythm stabilization and relief from congestive heart failure (CHF). Transcutaneous phototherapy devices (LifeWave Inc, San Diego, USA) may provide similar benefit without the need for opsin expression in the heart or exogenous light sources.
Objective: To investigate whether upregulation of carnosine activity using a wearable cutaneous phototherapy device may improve echocardiographic measures of left ventricular systolic function.
Methods: The Carnosine^® adhesive skin patch (34 mm diameter) contain an organic crystalline material that reflects specific frequencies of infra-red light emitted through the skin, and known to activate carnosine dipeptides throughout the body. These function as a high-energy phosphate system known to enhance muscle function. Study participants (n=12 healthy volunteers, 40-66 years of age) underwent a focused baseline echocardiogram, which included atrial (A) and early (E) mitral valve inflow, peak tissue velocity (E’) at both the lateral and septal mitral annulus, and left ventricular ejection fraction (LVEF). 10-12 patches were then applied along the sternum and across the left thorax (3^rd-5^th interspace), incorporating the anterior axilla. The echocardiogram was repeated after 20-30 minutes.
Results: LVEF was improved following application of the phototherapy device, increasing from 59.4±5.8% to 66.65±5.8% (Δ 6.3%, p<0.05), predicting an improvement in overall cardiac function. In those with normal diastolic function at baseline, septal E’ increased 7.3±0.57 cm/s to 8.2±0.58 cm/s (Δ 0.87 cm/s, p<0.05), indicating a direct effect on contractility. E and A wave velocities increased 2.46±0.14 cm/s and by 5.7±0.72 cm/s, indicating augmented hemodynamics trending towards significance.
Conclusion: Cutaneous phototherapy devices may enhance left ventricular systolic function without the need for drug delivery, gene manipulation, or exogenous light sources.