Abstract P277: The Influence of Interval Training on Physical Capacity and Exercise-induced Ischemia in Patients with Coronary Artery Disease

Abstract

Introduction: Patients(pts) with CAD referred for cardiac rehabilitation on the out-patient basis include those whose exercise stress test(EST) has been positive. The limit of the training heart rate(HR) is set below the ischemic threshold (IT), which result from angina and/or ischemic ST segment depression by ≥1 mm during an exercise test. The literature provides few original studies of this issue, and the answers to the question if ischemia during exercise should be avoided are inconsistent. Objectives: The aim of the study was to compare the safety and effectiveness of interval training at and below IT, and its influence on physical capacity and exercise-induced ischemia in pts with CAD and positive exercise stress test. Methods: The study comprised 30 clinically stable pts with positive EST, aged 55.22±10.29 years, after myocardial infarction and/or surgically treated ischemic heart disease, who were included in a cardiac rehabilitation program one month following MI or CABG. All subjects were divided into two groups: Group A-training at IT i.e. HR at which 1-mm ST depression appeared during the initial EST ( n=10),group B -training below IT i.e. HR10 bpm lower than the one at which 1-mm ST appeared ( n=20).All of them underwent a two-month interval training on cycloergometer three times a week. EST was performed before and after the completion of the training program(TP). The following variables were assessed: walking distance, WD (m), EST duration (min), metabolic equivalent (METs), time to 1 mm ST depression (min), max ST depression (mm).Also adverse events that occurred during training were analyzed. Results: After TP, following analyzed variables improved significantly in Group A: WD- 706.90±101.02 vs 770.90±139.78, p<0.05; EST duration - 10.15±3.89 vs 11.11±3.94, p<0.01; METs- 8.19±1.33 vs 9.27±1.89, p<0.05; time to 1mm ST depression- 9.08±4.27 vs 10.33±3.74,p< 0.01. The analyzed variables of Group B pts also improved: WD- 541.50±204.48 vs 646.30±175.72, p<0.01; EST duration- 8.49±3.01 vs 10.44±3.33, p<0.01; METs- 6.54±2.00 vs 7.83±1.2, p< 0.01; time to 1 mm ST depression- 7.89±3.30 vs 9.03±2.82,p <0.05 .Yet no significant decreasing of max ST depression in EST after TP in either group was observed. The assessment also included comparing the outcome of both forms of training finding no significant differences in the percentage changes in all parameters studied between the groups. No severe adverse events were reported during trainings. Conclusions 1.Both forms of interval training below and at ischemic threshold enhanced the physical capacity and had an anti-ischemic effect. 2.Interval training at ischemic threshold was an equally effective and safe form of rehabilitation as the training according to the current standards.