Patrick A. Gorman

Effects of a prescribed supervised exercise program on mortality and cardiovascular morbidity in patients after a myocardial infarction: The National Exercise and Heart Disease Project∗☆

This study enrolled 651 men with myocardial infarction in five participating centers in a randomized 3 year clinical trial of the effects of prescribed supervised exercise. The subjects, aged to 30 to 64 years, were screened for eligibility 2 to 36 months after their qualifying myocardial infarction. The men in the exercise group pursued intensive exercise in the laboratory for 8 weeks and then in a gymnasium for 34 months. The experience of the exercise group was more favorable than that of the control group in most of the comparisons made. The cumulative 3 year total mortality rate was 7.3 percent for the control group and 4.6 percent for the exercise group; the 3 year rate for recurrent myocardial infarction was 7.0 and 5.3 percent, respectively. Mortality rates in the two groups did not differ significantly, but the data were consistent with an assumption of substantial benefit from exercise. Adjustment for small differences in baseline variables by multivariate methods did not materially alter the estimate of effect of exercise. Certain subgroups showed a greater benefit from exercise.

Fibrinolytic Activity Is Similar in Physically Active Men With and Without a History of Myocardial Infarction

The purpose of this study was to evaluate fibrinolytic potential at rest and after a fibrinolytic stressor in men with a history of myocardial infarction (MI) compared with an age- and activity-matched group of men without coronary artery disease (CAD). All men were currently enrolled in exercise programs. Tissue-type plasminogen activator (TPA) and plasminogen activator inhibitor 1 (PAI-1) activity and antigen levels were measured at rest and after a maximal exercise test. A 2 x 2 (group x time) ANOVA with repeated measures was used to evaluate fibrinolytic potential. Bivariate regressions were conducted to evaluate relations between fibrinolytic potential and maximal oxygen uptake (VO2max). Age was similar between groups (CAD, 57.5 +/- 6.6; non-CAD, 58.1 +/- 7.3 years); however, VO2max was higher in non-CAD subjects (36.2 +/- 6.2 vs 27.5 +/- 5.9 mL.kg-1.min-1). Mean +/- SEM resting TPA and PAI-1 activities were similar between CAD and non-CAD subjects (TPA, 2.8 +/- 0.2 vs 2.8 +/- 0.2 IU/mL; PAI-1, 15.9 +/- 3.1 vs 13.1 +/- 4.1 AU/mL). Both groups showed similar significant increases in TPA activity with exercise (P < .05), and postexercise TPA activity was also similar (CAD, 9.1 +/- 2.0 IU/mL; non-CAD, 11.7 +/- 2.6 IU/mL). Both groups also showed similar significant decreases in PAI-1 activity with exercise (P < .05) and no differences in postexercise PAI-1 activity (CAD, 13.2 +/- 2.5 AU/mL; non-CAD, 10.4 +/- 3.6 AU/mL). Significantly higher resting TPA antigen levels were seen in CAD (14.8 ng/mL) than non-CAD (10.2 ng/mL) subjects (P < .05), but neither group showed significant changes with exercise (CAD, 12.9 ng/mL; non-CAD, 11.8 ng/mL). Resting PAI-1 antigen was similar in the two groups (CAD, 71.4 ng/mL; non-CAD, 74.2 ng/mL) and did not significantly change with exercise (CAD, 77.9 ng/mL; non-CAD, 72.3 ng/mL). VO2max was positively correlated with postexercise TPA activity (r = .52, P < .05) and negatively correlated with resting TPA antigen (r = -.43, P < .05). Resting TPA antigen was also directly correlated with body mass index (r = .63, P < .05). The finding that functional fibrinolytic activity was not different in physically active men with and without CAD contrasts with previous reports. This suggests that matching subjects on the bases of age and habitual physical activity status and controlling exercise intensity are important factors to consider when evaluating fibrinolytic potential.

Maximal Exercise Systolic Pressure, Exercise Training, and Mortality in Myocardial Infarction Patients

The relation of maximal exercise systolic pressure to physical conditioning and to mortality was determined in 641 men with > or =1 myocardial infarctions. Each performed a standardized multistage exercise test before randomized assignment either to an exercise group or a control group and at scheduled periodic intervals over 3 years. This study compares 123 men with maximal exercise systolic pressures (MESP) of < or =140 mm Hg with 518 men whose maximal exercise systolic pressure was > or =140 mm Hg. At baseline, the 2 groups were comparable for age, entry time since the occurrence of the qualifying cardiac event, and reported use of antihypertensive medications. Men with low MESP used more beta blockers, had lower systolic pressure measurements at rest and by definition at maximal exercise, and lower work capacity than men with higher levels of MESP. Men with low MESP experienced: (1) no reduction in mortality with exercise conditioning (p<0.86), and (2) a significantly higher mortality rate over 3 years (p<0.003) compared with men with higher levels of MESP. The relation of a low MESP to mortality persisted: (1) whether MESP or work capacity increased from the baseline exercise test to the last performed exercise test, and (2) whether it was measured at low (<6 METs) or high (> or =6 METs) levels of work capacity. We conclude that low maximal exercise systolic blood pressure is a predictor of mortality and is associated with an ineffective training response in men with myocardial infarction.

Effects of age and heart disease on the QRS axis during the seventh through the tenth decades

Abstract The mean frontal plane QRS axis of 658 patients between 60 and 94 years of age was obtained: 313 (48 per cent) were males, and 345 (52 per cent) were females. There were 308 patients without cardiovascular disease (Group I) and 350 patients with cardiovascular disease (Group II). These were divided by age into 5-year subgroups. In Group I the mean of the QRS axis showed no significant trend to the left with age, whereas in Group II there was a marked leftward trend in the ninth and the tenth decades. In the last three 5-year subgroups the means of the frontal plane QRS axis in Group I were 16.8, 23.2, and 22.2 degrees, respectively, and corresponding values in Group II were 5.1, 0.6, and −15.6 degrees. The differences between the means in the last two subgroups are statistically significant. The proportion with left axis deviation (−30 degrees or above) was greater in Group II than in Group I, particularly in the last two 5-year subgroups. The percentages were as follows: Group II, 26 and 42; Group I, 12 and 8.

Transmission of electrocardiograms from a community hospital for remote computer analysis

Abstract A system has been established for the telephone transmission of electrocardiograms from Hartford Hospital, Hartford, Conn., for remote computer analysis. The Medical Systems Development Laboratory computer center in Washington, D.C. provides computer-generated reports for all ambulatory patient electrocardiograms at this institution. The accuracy of computer diagnoses was studied in a group of 400 consecutive electrocardiograms by comparing the computer-generated reports with standard interpretations. This “standard” was attained by physician review of independent sight reading and computer interpretation. Eighty-five per cent of computer reports were judged acceptable. Eighty-seven per cent of individual “standard” diagnosis were correctly identified by computer. No false normal readings were noted, at the expense of some over-reading. Computer electrocardiographic reports were judged useful as an aid to clinical electrocardiographic reading, thus reducing physician time for interpretation five-fold. However, final physician review is always mandatory prior to use of the data in patient care.

Fibrinolytic activity is not dependent upon exercise mode in post-myocardial infarction patients

Abstract In this study we investigated possible differences in fibrinolytic activity in cardiac patients while they performed treadmill and cycle ergometry. Thirteen post-myocardial infarction patients completed two maximal exercise tests on treadmill and cycle ergometers. Blood was collected before and after each exercise test and was analyzed for the fibrinolytic variables, tissue plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) activity, and lactate. Maximal oxygen uptake, heart rate, and ventilation were greater (P < 0.05) on the treadmill than during cycle ergometry, however, blood lactate was similar between modes. t-PA activity significantly increased with exercise (P < 0.05) and there was a trend toward a reduction in PAI-1 activity with exercise, but this did not reach statistical significance. The fibrinolytic responses to maximal exercise did not differ between the two modes of exercise studied. Therefore, exercise intensity, but not the mode of exercise, appeared to be the primary determinant of the fibrinolytic response to acute exercise in these patients.

Impact of steady-state and exercise modality on estimating oxygen consumption in men with and without coronary artery disease

PURPOSE This study examined the effect of steady-state on the ability of 15 men with coronary artery disease (CAD) and 13 men without CAD disease (non-CAD) to reach a rate of oxygen consumption (VO2) relative to population norms during treadmill and cycle ergometry exercise testing. METHODS Subjects completed a maximal graded exercise test on the treadmill and cycle ergometry involving 3-minute stages and a submaximal exercise test involving 6-minute stages to 80% of maximal effort. Estimates of VO2 were derived from commonly cited clinical estimation equations. RESULTS Only the Foster equation accurately estimated maximal VO2 during a treadmill graded exercise test in patients with CAD. However, each of cited clinical equations accurately estimated maximal VO2 during a treadmill graded exercise test in the non-CAD group. No equation accurately estimated VO2 at submaximal efforts during treadmill exercise for either group. Cycle ergometry estimation equations accurately estimated VO2 in both groups at maximal effort, but were inconsistent at submaximal efforts. Both the CAD and the non-CAD group reached steady-state VO2 within 3 minutes, at submaximal workloads. CONCLUSIONS The inability to attain an expected VO2 during exercise did not seem related to steady-state VO2 because both CAD and non-CAD groups readily reached steady-state VO2, though the estimation of VO2 remained inaccurate for most treadmill estimation equations. Because VO2 was accurately estimated for cycle ergometry exercise, estimation accuracy seems to be influenced by exercise modality.