Effect of exercise-based cardiac rehabilitation on the ischemic threshold in patients with high-risk ischemic heart disease
Authors: Lara Vargas J A , Pereira-Rodriguez J E , Perez-Vazques D I , Leyva-Valadez E , Lastra-Silva V J , Penaranda Florez D G , Xavier-Santos G , Galdino G 
Published: October 2022

Abstract

Introduction
Coronary artery disease is a complex condition and is not always resolved after an interventional or surgical procedure, due to the remaining obstructions in the coronary tree or the severity of the atherosclerosis, leaving anginal symptoms, ischemic threshold (IU) in the exercise, decreased cardiorespiratory fitness, and poor quality of life (QoL). Exercise-based cardiac rehabilitation programs (Ex-CRP) usually develop ischemic preconditioning mechanisms thanks to their direct anti-inflammatory, antioxidant, antithrombotic and coronary neovascularization effects, thus improving coronary reserve flow. We hypothesize that an Ex-CRP is capable of favorably impacting the UI in these patients. Therefore, the objective of this study is to evaluate the effects of an Ex-CRP on the UI in patients with high-risk ischemic heart disease.

Methods
Quasi-experimental study with 121 patients with ischemic threshold due to high-risk ischemic heart disease (with perfusion defects in nuclear medicine, complex coronary anatomy or partially revascularized) and presence of ischemic threshold in the exercise test. An Ex-CRP of 4–6 weeks duration was performed, consisting of supervised and monitored training concurrent with 30-minute aerobic exercise sessions at 70% of heart rate reserve, 3 times per week, supplemented with resistance exercise. and an educational understanding program for the control of risk factors and nutritional and psycho-emotional care. At the end of the program, a stress test was performed to compare the post-intervention effects and ischemic threshold was defined as the presence of angina or electrocardiographic changes of ischemia with negative ST-segment depression in 2 consecutive beats more than 80 ms from the J point. and in more than two contiguous leads.

Results
The 121 patients with ischemic threshold were 61±10 years old and 75% were male. On the other hand, 29.7% had a diagnosis of heart failure and an average LVEF of 53.1±12.9%. After Ex-CRP, an improvement was found in calculated VO2p (24.7±7.8 vs 34.23±7.5; p=0.000), METs at maximum effort from 7.06±2.15 to 9.78±1.14 (p&lt;0.0001) and submaximal load in watts from 44±21.32 to 61±24.49; p&lt;0.0001. 40.5% of the patients who were admitted with UI resolved it (absence of post-intervention ischemic diagnosis) after Ex-CRP and the remaining percentage with UI (59.5%) displaced it by 2.62 METs (p&lt;0.0001). With this, the cardiovascular risk calculated by the Duke Score also decreased from −7 to −2 (p&lt;0.0001), and the myocardial efficiency index improved from 8 to 6 (p&lt;0.0001), strength (79±15 to 92±8%; p&lt;0.0001) and QoL (65±17 vs 82±12; p&lt;0.0001).

Conclusions
Ex-CRP had a significant effect on the resolution or displacement of the UI in patients with high-risk ischemic heart disease. In addition, it improved muscle strength, quality of life, myocardial efficiency, and reduced the cardiovascular risk index calculated by the Duke score.

Funding Acknowledgement
Type of funding sources: Private company. Main funding source(s): Centro de Estudios e Investigaciόn FISICOL. Cúcuta, ColombiaCardioFit. CDMX, México