Exercise and Cardiac Rehabilitation Cardiology 1992:80:406-412
Unidad de Rehabilitación Cardíaca, Servicio de Cardiología, Hospital General Universitari. Valencia, España
KeyWords Coronary artery disease Ischemia Exercise training Cardiac rehabilitation
Effects of a 1- Year Exercise Training Program on Myocardial Ischemia in Patients after Myocardial Infarction Abstract To determine the effects of exercise training on exerciseinduced ischemia in patients following myocardial infarction, the experience of 13 patients with exercise-induced ST depres sion, who were moderate-to-high intensity trained for 1 year, has evaluated. After training, the maximum ST depression was significantly less (1.9 ± 0.8 vs. 1.1 ± 0.8 mm: p < 0.01), despite an increased maximal rate-pressure product (RPP; heart rate X blood pressure/100: 241.3 ± 44 vs. 262.0 ± 58; p < 0.01). For the onset of 0.1 mV of ST depression, we found a significant increase in RPP from 204.1 ± 34.7 to 234.1 ± 49.4 (p < 0.01) and also in heart rate (117.1 ± 15.1 vs. 125.1 ± 21.7 b.p.m.; p < 0.05), blood pressure (167.6 ± 18 vs. 180.3 ± 18 mm Hg: p < 0.01) and workload (93.8 ± 17.4 vs. 121.1 ± 23.2 W; p < 0.01). The relationship between ST depression and RPP (RPP/STmax) was favorably modified after training. The ratio RPP/STmax improved significantly from 143.6 ± 49.4 to 209.1 ± 69.5 (p < 0.0001). These find ings support the hypothesis that a 1-year moderate-to-high training program in some patients following myocardial in farction can elicit adaptations that may well be attributed, at least in part, to an improvement in coronary blood flow.
Introduction Cardiovascular response to physical train ing in patients following myocardial infarc tion with exercise-induced ischemia has not
This study was presented in part at the 11th Congress o f the European Society of Cardiology. Nice, France, September 12. 1989.
Received: February 8. 1992 Accepted: February' 11.1992
been fully clarified [1-5]. The well-docu mented effects of training include an in creased physical working capacity and a re duced oxygen demand by the heart at a given workload, and they are usually thought to be
Francisco Ridocci. MD Hospital General Universitari Marqués de San Juan 2, 6a E-46015 Valencia (Spain)
©1992 S. Karger AG. Basel 0008-6312/92/ 0806-0406$ 2.75/0
Downloaded by: Univ. of California Santa Barbara 128.111.121.42 - 3/30/2018 5:44:11 PM
Francisco Ridocci José A. Velasco Ildefonso Echánove Guillermo Soriano Maria Cruz Torregrosa Ra fael Payó Aurelio Quesada
Methods Study Subjects
All patients enrolled in our Postinfarction Rehabil itation Program between April 1981 and December 1987 were considered for the study. Inclusion criteria were: (a) completion of I year of exercise training: (b) achievement of a training effect during this time: (c) exercise-induced ST-segment depression > 0 .1 mV on initial exercise test; (d) no changes in cardiac medi cation. and (e) no digoxin or amiodarone therapy. Thirteen males, aged 4 1-64, who fulfilled these cri teria, were finally selected. Nine patients were taking nitrates; 5 were on p-blockers. 3 of them in combina tion with nitrates; I patient was on calcium antagonist, and the other received no medication. Exercise Testing
Symptom-limited exercise testing was carried out before and after the training period. The exercise tests were performed on a bicycle in an upright position with a multistage protocol, starting with 50 W and increasing by 25 W every 3 min. using a SiemensElema ergometer with electromagnetic brakes. No medications were discontinued for the tests. Conven tional 12-lead ECG and systolic blood pressure ob tained by a cuff sphygmomanometer were recorded at rest, every minute during exercise and on recovery; V5 was continuously monitored during the test. The exer cise tests were stopped when one of the following five criteria appeared: (I) severe or increasing angina; (2) potentially dangerous arrhythmias: (3) fall in systolic blood pressure > 2 0 mm Hg; (4) severe dyspnea or fatigue, and (5) attainment of a maximum ST segment depression of 0.4 mV. The following parameters were evaluated: physical working capacity: heart rate: systolic blood pressure: and RPP (heart rate X blood pressure/100) at the appearance of 0 .1 mV of ST-segment depression, and at peak exercise and maximum ST-segment depression. The ischemic threshold was defined as the RPP at which an ischemic ST-segment depression of 0.1 mV at 80 ms after J point was present during exercise or at peak exercise at the second test in case of a negative result. Evaluation of ECG changes was by blinded inde pendent review of the exercise electrocardiograms by two experienced cardiologists. Disagreements in inter pretation were resolved by consensus. Physical Training
The interval between myocardial infarction and initiation of the training program ranged from 8 weeks
407
Downloaded by: Univ. of California Santa Barbara 128.111.121.42 - 3/30/2018 5:44:11 PM
based on peripheral adaptations without changes in myocardial function [5. 6]. Nev ertheless, animal studies have shown signifi cant changes in myocardial perfusion after training [7-9], and selected studies [10-16] with a limited number of patients have indi rectly supported the hypothesis that training promotes improved myocardial blood flow as reflected by an increased heart rate [10] or rate-pressure product (RPP) at the onset of electrocardiographic evidence of ischemia [11, 13. 14], a lesser degree of ST-segment changes at the same RPP [12] and reduced stress-induced ischemia assessed by radionu clide techniques despite constant or even in creased myocardial oxygen consumption [15, 16], However, other investigators have not observed these effects [17-27], Differences in patient selection, inadequacy of assessment methods or the intensity and duration of training are probably responsible for these discrepancies in results. Because exercise-induced ST-segment de pression is most likely caused by ischemia in patients with known coronary artery disease [2. 28], and the RPP is generally considered the most accurate noninvasive index of myo cardial oxygen consumption during exercise [29, 30], the improvement in the relationship between the RPP and the degree of ST-seg ment depression would reflect an improve ment in the coronary blood flow, taking into account that the magnitude of the ST-segment depression during exercise and the indices expressing myocardial oxygen requirements are closely correlated [31], In order to test this hypothesis, we re viewed the experience of our rehabilitation center.
Statistical Analysis
Differences among data obtained before and after training were analyzed using Student’s t test for paired data. A p value
Unidad de Rehabilitación Cardíaca, Servicio de Cardiología, Hospital General Universitari. Valencia, España
KeyWords Coronary artery disease Ischemia Exercise training Cardiac rehabilitation
Effects of a 1- Year Exercise Training Program on Myocardial Ischemia in Patients after Myocardial Infarction Abstract To determine the effects of exercise training on exerciseinduced ischemia in patients following myocardial infarction, the experience of 13 patients with exercise-induced ST depres sion, who were moderate-to-high intensity trained for 1 year, has evaluated. After training, the maximum ST depression was significantly less (1.9 ± 0.8 vs. 1.1 ± 0.8 mm: p < 0.01), despite an increased maximal rate-pressure product (RPP; heart rate X blood pressure/100: 241.3 ± 44 vs. 262.0 ± 58; p < 0.01). For the onset of 0.1 mV of ST depression, we found a significant increase in RPP from 204.1 ± 34.7 to 234.1 ± 49.4 (p < 0.01) and also in heart rate (117.1 ± 15.1 vs. 125.1 ± 21.7 b.p.m.; p < 0.05), blood pressure (167.6 ± 18 vs. 180.3 ± 18 mm Hg: p < 0.01) and workload (93.8 ± 17.4 vs. 121.1 ± 23.2 W; p < 0.01). The relationship between ST depression and RPP (RPP/STmax) was favorably modified after training. The ratio RPP/STmax improved significantly from 143.6 ± 49.4 to 209.1 ± 69.5 (p < 0.0001). These find ings support the hypothesis that a 1-year moderate-to-high training program in some patients following myocardial in farction can elicit adaptations that may well be attributed, at least in part, to an improvement in coronary blood flow.
Introduction Cardiovascular response to physical train ing in patients following myocardial infarc tion with exercise-induced ischemia has not
This study was presented in part at the 11th Congress o f the European Society of Cardiology. Nice, France, September 12. 1989.
Received: February 8. 1992 Accepted: February' 11.1992
been fully clarified [1-5]. The well-docu mented effects of training include an in creased physical working capacity and a re duced oxygen demand by the heart at a given workload, and they are usually thought to be
Francisco Ridocci. MD Hospital General Universitari Marqués de San Juan 2, 6a E-46015 Valencia (Spain)
©1992 S. Karger AG. Basel 0008-6312/92/ 0806-0406$ 2.75/0
Downloaded by: Univ. of California Santa Barbara 128.111.121.42 - 3/30/2018 5:44:11 PM
Francisco Ridocci José A. Velasco Ildefonso Echánove Guillermo Soriano Maria Cruz Torregrosa Ra fael Payó Aurelio Quesada
Methods Study Subjects
All patients enrolled in our Postinfarction Rehabil itation Program between April 1981 and December 1987 were considered for the study. Inclusion criteria were: (a) completion of I year of exercise training: (b) achievement of a training effect during this time: (c) exercise-induced ST-segment depression > 0 .1 mV on initial exercise test; (d) no changes in cardiac medi cation. and (e) no digoxin or amiodarone therapy. Thirteen males, aged 4 1-64, who fulfilled these cri teria, were finally selected. Nine patients were taking nitrates; 5 were on p-blockers. 3 of them in combina tion with nitrates; I patient was on calcium antagonist, and the other received no medication. Exercise Testing
Symptom-limited exercise testing was carried out before and after the training period. The exercise tests were performed on a bicycle in an upright position with a multistage protocol, starting with 50 W and increasing by 25 W every 3 min. using a SiemensElema ergometer with electromagnetic brakes. No medications were discontinued for the tests. Conven tional 12-lead ECG and systolic blood pressure ob tained by a cuff sphygmomanometer were recorded at rest, every minute during exercise and on recovery; V5 was continuously monitored during the test. The exer cise tests were stopped when one of the following five criteria appeared: (I) severe or increasing angina; (2) potentially dangerous arrhythmias: (3) fall in systolic blood pressure > 2 0 mm Hg; (4) severe dyspnea or fatigue, and (5) attainment of a maximum ST segment depression of 0.4 mV. The following parameters were evaluated: physical working capacity: heart rate: systolic blood pressure: and RPP (heart rate X blood pressure/100) at the appearance of 0 .1 mV of ST-segment depression, and at peak exercise and maximum ST-segment depression. The ischemic threshold was defined as the RPP at which an ischemic ST-segment depression of 0.1 mV at 80 ms after J point was present during exercise or at peak exercise at the second test in case of a negative result. Evaluation of ECG changes was by blinded inde pendent review of the exercise electrocardiograms by two experienced cardiologists. Disagreements in inter pretation were resolved by consensus. Physical Training
The interval between myocardial infarction and initiation of the training program ranged from 8 weeks
407
Downloaded by: Univ. of California Santa Barbara 128.111.121.42 - 3/30/2018 5:44:11 PM
based on peripheral adaptations without changes in myocardial function [5. 6]. Nev ertheless, animal studies have shown signifi cant changes in myocardial perfusion after training [7-9], and selected studies [10-16] with a limited number of patients have indi rectly supported the hypothesis that training promotes improved myocardial blood flow as reflected by an increased heart rate [10] or rate-pressure product (RPP) at the onset of electrocardiographic evidence of ischemia [11, 13. 14], a lesser degree of ST-segment changes at the same RPP [12] and reduced stress-induced ischemia assessed by radionu clide techniques despite constant or even in creased myocardial oxygen consumption [15, 16], However, other investigators have not observed these effects [17-27], Differences in patient selection, inadequacy of assessment methods or the intensity and duration of training are probably responsible for these discrepancies in results. Because exercise-induced ST-segment de pression is most likely caused by ischemia in patients with known coronary artery disease [2. 28], and the RPP is generally considered the most accurate noninvasive index of myo cardial oxygen consumption during exercise [29, 30], the improvement in the relationship between the RPP and the degree of ST-seg ment depression would reflect an improve ment in the coronary blood flow, taking into account that the magnitude of the ST-segment depression during exercise and the indices expressing myocardial oxygen requirements are closely correlated [31], In order to test this hypothesis, we re viewed the experience of our rehabilitation center.
Statistical Analysis
Differences among data obtained before and after training were analyzed using Student’s t test for paired data. A p value
