Terence Kavanagh

Prediction of Long-Term Prognosis in 12 169 Men Referred for Cardiac Rehabilitation

Background—Predicting the risk of cardiac and all-cause death in patients with established coronary heart disease is important in counseling the individual and designing risk-stratified rehabilitation and secondary prevention programs. Cox proportional hazards and Kaplan-Meier survival curves were thus completed on initial assessment data obtained from patients referred to an outpatient cardiac rehabilitation center. Methods and Results—A single-center prospective observational design took peak cardiorespiratory exercise test data for 12 169 male rehabilitation candidates aged 55.0±9.6 years (7096 myocardial infarctions [MIs], 3077 coronary artery bypass grafts [CABGs], and 1996 documented cases of ischemic heart disease [IHD]). A follow-up of 4 to 29 years (median, 7.9) yielded 107 698 man-years of experience. Entry data were tested for associations with time to cardiac and all-cause death. We recorded 1336 cardiac deaths (953 MI, 225 CABG, and 158 IHD) and 2352 all-cause deaths. A powerful predictor of cardiac and all-cause mortality was measured peak oxygen intake (&OV0312;o2peak). For the overall sample, values of <15, 15 to 22, and >22 mL/kg per minute yielded respective multivariate adjusted hazard ratios of 1.00, 0.62, and 0.39 for cardiac and 1.00, 0.66, and 0.45 for all-cause deaths. For the separate diagnostic categories, apart from &OV0312;o2peak, the only other significant predictors of cardiac death common to all 3 were smoking and digoxin, and for all-cause death, age, smoking, digoxin, and diabetes. Conclusions—Exercise capacity, as determined by direct measurement of &OV0312;o2peak, exerts a major long-term influence on prognosis in men after MI, CABG, or IHD and can play a valuable role in risk stratification and counseling.

Cardiorespiratory responses to exercise training after orthotopic cardiac transplantation.

We have tested the feasibility and effectiveness of a 2 year (average 16 +/- 7 months) walk/jog exercise program on 36 male orthotopic cardiac transplant patients (21 to 57 years old) seen initially 2 to 23 months after surgery. Comparison of initial exercise test results with those in 45 age-matched normal men showed the patients to have a lesser lean body mass (56 +/- 7 vs 63 +/- 8 kg, p less than .001), with a higher resting heart rate (104 +/- 12 vs 77 +/- 14 beats/min, p less than .001) and systolic (138 +/- 16 vs 129 +/- 17 mm Hg, p less than .001) and diastolic (95 +/- 14 vs 84 +/- 10 mm Hg, p less than .001) blood pressures. Peak power output was less than normal (101 +/- 27 vs 219 +/- 41 W, p less than .001), as was peak heart rate (136 +/- 15 vs 176 +/- 13 beats/min, p less than .001), peak oxygen intake (VO2max) (22 +/- 5 vs 34 +/- 6 ml.kg.min-1, p less than .001), and absolute anaerobic threshold (1.18 +/- 0.40 vs 2.04 +/- 0.40 liters.min-1, p less than .001). Peak ventilatory equivalent was h...

Reasons for dropout from exercise programs in post-coronary patients.

The dropout rate in the 7-yr Ontario Exercise Heart Collaborative Study of post-coronary men engaged in exercise programs was examined in order to determine possible contributing factors. A questionnaire pertaining to psychosocial and program-related variables was distributed to 728 subjects who were previously assigned randomly on the basis of four prognostic risk factors (occupation, personality, hypertension, and angina) into exercise groups: low intensity exercise (LIE), and high intensity exercise (HIE). Comparisons of answers by the 639 respondents (266 dropouts; 373 compliers) were made initially by chi-square analysis to determine significant categories of questions and, subsequently, by a logistic transform to determine the specific questions which related significantly to the dropout rate. It was found that three main categories were associated with a high dropout rate: convenience aspects of the exercise center, perceptions of the exercise program, and family/lifestyle factors. These three main categories should be carefully considered when designing and implementing potential compliance-improving strategies for secondary prevention exercise programs entailing long-term adherence.

Relation of exercise to the recurrence rate of myocardial infarction in men: Ontario exercise-heart collaborative study

The Ontario Exercise-Heart Collaborative Study was a multicenter randomized clinical trial of high Intensity exercise for the prevention of recurrent myocardial infarction in men. The 4-year recurrence rate among 379 patients on a program of high intensity exercise did not differ significantly from that among 354 control patients on a program of light exercise, despite the greater reduction in heart rate in the former group. The relative odds of recurrence in the high intensity group were 1.09, with 95% confidence limits of 0.61 and 1.96.

Predictors of dropout from cardiac exercise rehabilitation: Ontario exercise-heart collaborative study*

The Ontario Exercise-Heart Collaborative Study was a multicenter randomized clinical trial of high intensity exercise for the prevention of recurrent myocardial infarction in 733 men. Of the 678 subjects who could have participated for at least 3 years, 315 (46.5%) dropped out. Stepwise multiple linear logistic regression analysis was carried out to examine the relation between subject characteristics and the probability of dropping out during the study. Analysis was performed on the entry group as a whole by considering those subjects who had reinfarction while complying with the program and also by excluding all subjects with reinfarctions. The consistent and statistically significant predictors of dropout in both analyses were smoking and a blue collar occupation. Angina was significantly associated with dropout only when reinfarctions were excluded. It may be important to consider these factors when investigating the potential for compliance-improving strategies in reducing dropout from exercise rehabilitation programs.

Exercise training for patients with chronic atrial fibrillation.

BACKGROUND Patients with atrial fibrillation (AF) referred for exercise rehabilitation exemplify the problem inherent in reliance on pulse rate to prescribe and monitor training intensity. METHODS Exercise training was accomplished by specifying a training walking pace based on 60% to 80% of the peak oxygen intake (VO2max), as determined by the analysis of expired air (Horizon metabolic cart), and/or the ventilatory threshold (VT), together with a perceived exertion of 12 to 14 on the original Borg scale of perceived exertion. RESULTS At the end of 1 year, a significant training effect was demonstrated (VO2max average increase 15%, 14.8 +/- 3.6 mL/kg/min to 17.0 +/- 3.6 mL/kg/min, P < .02; VO2 at VT, average increase 14%, 11.2 +/- 2.2 to 12.8 +/- 2.6 mL/kg/min, P < .01; peak power output increase 21%, 92.5 +/- 29.3 Watts to 112 +/- 3.7 Watts, P < .05) in a group of 20 patients (13 men, 7 women) with chronic atrial fibrillation. CONCLUSIONS Patients with chronic atrial fibrillation can achieve significant functional gains from an exercise rehabilitation program.

The Toronto Cardiac Rehabilitation and Secondary Prevention Program: 1968 into the new millennium.

Given our approach to the cardiac rehabilitation process, which is reflected in the program structure and services and our high patient volume, this program model is effective for us. The model permits us to treat relatively large number of patients with relatively small numbers of staff. On average, a patient attends 32 supervised exercise sessions at the Centre over the course of 12 months. This is actually fewer supervised sessions than the popular model of 3 times per week for 12 weeks. However, the 12-month program provides an additional 9 months to work with patients on heart-healthy lifestyle modifications. At the same time, we realize our model is not the model of choice for all people in all settings for a variety of reasons. We trust that some elements of our program may be of interest and beneficial to some readers. Undoubtedly, the program will continue to evolve and develop into the future. Currently, we are conducting a cardiac rehabilitation outcomes study in an effort to determine the appropriate duration of cardiac rehabilitation to achieve optimal physiological, psychological, and cost benefits for patients. This study involves more than 700 patients and the results are intended to help us further refine the program structure and selected program elements. As the new millennium approaches, healthcare system reforms and continuing changes in the delivery of medical care to cardiac patients present opportunities, challenges, and some uncertainties for cardiac rehabilitation. To continue our services to patients and the medical community, cardiac rehabilitation programs will need to identify and develop even more innovative and effective concepts in response to ever-changing local, regional, and national issues.

Marathon Running After Cardiac Transplantation: A Case History

A 45-year-old male cardiac transplant patient (one of 58 such subjects taking part in an ongoing pilot project involving Harefield Hospital, Middlesex, England, and the Toronto Rehabilitation Centre, Canada) was given a medically prescribed 11-month endurance-type (walking/jogging) rehabilitation ex

The effects of continued training on the aging process.

Several previous reports 1-6 have described the physiological characteristics of small samples of middle-aged and elderly athletes. At least one report has claimed that aerobic power ages more slowly in the continuing athlete than in the general population, although this view seems based mainly on an unusually rapid deterioration of the control sample, the annual loss of maximum oxygen intake among the athletes being much as seen in other large cross-sectional surveys of average citizens.7, Until recently, only a small proportion of athletes have continued to participate in international competitions after the age of 40 years. Those tested in middle and later life have thus been a highly selected subsample of the original athletic population, including varying proportions of star competitors and subjects no longer engaged in rigorous training. The development of age-specific contests has greatly increased the popularity of track and field events for elderly competitors, to the point where cross-sectional data on such subjects can be used to explore the probable response of the average person to a lengthy period of hard physical training. The hosting of the World Masters’ Championships in Toronto in August, 1975 provided us with the opportunity to question and examine a substantial number of middle-aged and elderly track competitors. The results obtained form the basis of the present report.

Central and peripheral adaptations after 12 weeks of exercise training in post-coronary artery bypass surgery patients.

PURPOSE Training adaptations in patients with coronary artery disease (CAD) have been reported previously, but little is known about central and peripheral adaptations in those recovering from coronary artery bypass graft surgery (CABG). The purpose of this study was to examine the effects of 12 weeks of endurance exercise training on exercise performance and left ventricular and peripheral vascular reserve in a group of uncomplicated CABG patients. METHODS Thirty-one patients were recruited and began training 8 to 10 weeks after uncomplicated CABG. Patients underwent progressive exercise training consisting of walking and jogging, at 75% to 80% maximal oxygen intake (VO2max). Measures of left ventricular function included ejection fraction (EF), ventricular volumes, and the pressure volume ratio, an index of contractility. Peak ischemic exercise calf blood flow and vascular conductance was determined using strain-gauge plethysmography. Maximal oxygen intake and submaximal blood lactate concentration also was determined. RESULTS A significant improvement in VO2max (1497 +/- 60 mL/min versus 1691 +/- 71 mL/min) was observed after training. This change was accompanied by an increase in the EF during submaximal exercise (60 +/- 3% versus 63 +/- 2% at 40% VO2max; 61 +/- 3% versus 64 +/- 3% at 70% VO2max) (P < 0.05), and the change in EF from rest to exercise (delta EF). No changes were observed for ventricular volumes during exercise, although there was a trend for a higher stroke volume at 70% VO2max. A significant increase (18%) was observed for peak ischemic exercise calf blood flow and vascular conductance. In addition, submaximal blood lactate concentration was lower after training. CONCLUSIONS These data indicate that exercise training for 12 weeks in patients recovering from CABG can elicit significant improvements in functional capacity that, for the most part, are secondary to peripheral adaptations, with limited support for improvement in left ventricular function.