Développement d’un indice de vitalité dérivé à partir du Hexoskin afin d’obtenir une mesure d’angine digitale et raffiner l’étude de la maladie cardiaque athérosclérotique

Introduction :    Up to half of coronary artery disease patients will remain symptomatic of angina, despite coronary revascularization. Moreover, the assessment of angina suffers from the ischemic threshold adaptation bias where patients will restrict their physical activity level in order to minimize their angina symptoms. The NOVA-SKIN study (NCT02591758) was designed to use a novel “smart clothing” (Hexoskin™) to (i) validate the electrocardiogram (ECG) signal of against traditional Holter and Treadmill stress tests (ii) to derive a ‘vitality index’ using the biometric measures obtained from the Hexoskin in order to adjust conventional angina assessment metrics to account for the ischemic threshold adaptation bias and derive a digital measure of angina and to (iii) assess if home cardiac rehabilitation can be remotely monitored using the Hexoskin system.    Methods:    Thirty stable angina patients referred for coronary angiography for refractory angina underwent a treadmill stress test and then simultaneously wore the Hexoskin vest and a traditional Holter monitor for 48 hours, 2 weeks before their exam. The patients were followed up 2 weeks after the percutaneous coronary intervention and 6 weeks after their cardiac surgery if they had coronary artery bypass graft. During the follow-up visit, they wore the vest with a Holter monitor for 48 hours and underwent another treadmill stress test. We obtained an average vitality index pre- and post-angiogram (Vitality index=heart rate * activity) using recordings from the vest. We also obtained health related questionnaires during the same timeframe. We compared differences in conventional angina metrics adjusted for the vitality index (“digital angina”) with the conventional metrics unadjusted for the vitality index, pre- and post-coronary angiography. Patients then had to complete 6 home cardiac rehabilitation sessions during a 1-month period. Pearson correlation was obtained between the heart rate (HR) derived from the ECG of the vest and the HR of the Holter and treadmill stress test. The vitality index pre and post-angiography was compared using a t-test. We derived digital angina metrics by dividing or multiplying (according to the direction of the effect expected post-coronarography) the conventional angina metrics. Then we measured the effect size of the angina treatment and compared it between adjusted and unadjusted metrics within the same patient.    Results:    Thirty patients aged 68.0±7.0 years (93.3% men; n=28) were enrolled in the study. Patients were treated with percutaneous coronary intervention (n=20; 66.7%), coronary artery bypass grafting (n=6; 20.0%) or medical therapy (n=4; 13.3%). The heart rate from ECG signal of the Hexoskin demonstrated a very strong correlation with that of the treadmill stress test ECG (r=0.95) and a strong correlation with the Holter (r=0.85). The vitality index increased significantly from 2.30±1.38 to 2.70±1.12 (p=0.05). The digital angina metrics (adjusted for the vitality index) that were found to be more responsive to the treatment of the angina than conventional were: the weekly nitroglycerin count, the global health sub-scale of the SF-36, the treadmill stress test length and the peak METs. Furthermore, in patients classified as non-responders to the treatment of angina by conventional metrics, the digital angina measures improved significantly, when looking at the CCS class, the weekly angina count, the Seattle Angina Questionnaire metrics and the duration of exercise on the treadmill stress test. No adverse events occurred during home cardiac rehabilitation and 28 patients completed all 6 sessions wearing the Hexoskin.    Conclusion :    In our pilot study, the Hexoskin ECG was well correlated with standard HR measurement using a treadmill ECG or a Holter. Adjusting conventional metrics for the vitality index allows for greater sensitivity in gauging the effect of revascularization on angina than conventional metrics alone, particularly for patients who would be considered non-responders to their treatment based on conventional metrics. Home cardiac rehabilitation was safe and was completed by most patients.

Keyphrases: Angina, Atherosclerotic vascular disease, mHealth, mobile health, angina bias, biometric vest, technology, biometric vest, coronary revascularisation