Kenneth H. Cooper

Maximal exercise test as a predictor of risk for mortality from coronary heart disease in asymptomatic men

Exercise testing in asymptomatic persons has been criticized for failing to accurately predict those at risk for coronary heart disease (CHD). Previous studies on asymptomatic subjects, however, may not have been large enough or long enough to provide reliable outcome measures. This study examines the ability of a maximal exercise test to predict death from CHD and death from any cause in a population of asymptomatic men. This is a prospective longitudinal study performed between 1970 and 1989, with an average follow-up of 8.4 years. The subjects are 25,927 healthy men, 20 to 82 years of age at baseline (mean 42.9 years) who were free of cardiovascular disease and who were evaluated in a preventive medicine clinic. The main outcome measures are CHD mortality and all-cause mortality. During follow-up there were 612 deaths from all causes and 158 deaths from CHD. The sensitivity of an abnormal exercise test to predict coronary death was 61%. The age-adjusted relative risk of an abnormal exercise test for CHD death was 21 (6.9 to 63.3) in those with no risk factors, 27 (10.7 to 68.8) in those with 1 risk factor, 54 (21.5 to 133.7) in those with 2 risk factors, and 80 (30.0 to 212. 5) in those with >/=3 factors. A maximal exercise test performed in asymptomatic men free of cardiovascular disease does appear to be a worthwhile tool in predicting future risk of CHD death. An abnormal exercise test is a more powerful predictor of risk in those with than without conventional risk factors.

Association between coronary heart disease risk factors and physical fitness in healthy adult women.

We examined associations between physical fitness and risk factors for coronary heart disease in healthy women ages 18–65 years. Physical fitness was objectively determined by the duration of a maximal treadmill exercise test. Six physical fitness categories (very poor to superior), specific within 10- year age increments, were established. Mean risk factor levels varied across categories, but so did potential confounders such as age and weight. Multiple linear regression modeling was used to control for the effects of age, weight and year of exam on coronary risk factors. After adjustment, physical fitness was independently associated with triglycerides (p < 0.001), high-density lipoprotein cholesterol (HDL-C) (p ≤ 0.001), total cholesterol/HDL-C ratio (p ≤ 0.001), blood pressure (p ≤ 0.001) and cigarette smoking (p ≤ 0.001).

The safety of maximal exercise testing.

Previous reports on the safety of exercise testing have been based on surveys from different testing facilities with a variety of testing protocols and patient types. From 1971 through 1987, 71,914 maximal exercise tests conducted in a population with a low prevalence of known coronary heart disease under uniform conditions at a single medical facility resulted in six major cardiac complications including one death. No complications have occurred in the past 10 years in 45,000 maximal tests. The overall cardiac complication rate in men and women is 0.8 complications per 10,000 tests with 95% confidence intervals of 0.3-1.9 complications per 10,000 tests. Maximal exercise testing appears safer than some previously published reports have suggested and seems to be getting safer with time.

Physical activity versus cardiorespiratory fitness: two (partly) distinct components of cardiovascular health?

Physical activity (PA) and cardiorespiratory fitness (CRF) both have inverse relationships to cardiovascular (CV) morbidity and mortality. Recent position papers and guidelines have identified the important role of both of these factors in CV health. The benefits of PA and CRF in the prevention of CV disease and risk factors are reviewed. In addition, assessment methodology and utilization in the research and clinical arenas are discussed. Finally, the benefits, methodology, and utilization are compared and contrasted to better understand the two (partly) distinct components and their impact on CV health.

Relation of the Number of Metabolic Syndrome Risk Factors With All-Cause and Cardiovascular Mortality

The metabolic syndrome (MS) is a constellation of risk factors associated with diabetes and cardiovascular disease. This syndrome consists of at least 3 parameters assessing central obesity, hypertension, high-density lipoprotein cholesterol, triglycerides, and impaired glucose metabolism. Whether persons with 4 or 5 risk factors are at higher risk than those with 3 risk factors is unclear. Also unclear is whether those without the MS but with 1 or 2 risk factors warrant therapy. We assessed cardiovascular and all-cause mortality as a function of the number of these risk factors. We followed 30,365 men for a median follow-up of 13.6 years. During follow-up, 1,449 participants died, 527 from cardiovascular causes. All of the individual parameters defining the MS were significantly associated with both all-cause and cardiovascular mortality (p <0.001). After adjustment for age and the other MS variables, hypertension was the most potent risk factor whereas central obesity and hypertriglyceridemia remained associated with both all-cause and cardiovascular mortality. A highly significant trend was also noted between both all-cause or cardiovascular mortality and the number of risk factors (p <0.001 for trend). Risk increased incrementally, beginning at 1 risk factor for cardiovascular mortality and at 2 risk factors for all-cause mortality. In conclusion, there is a continuum of risk as the number of metabolic syndrome risk factors increases. These findings add to the growing evidence that central obesity can independently and adversely affect health.

Cardiorespiratory Fitness and Long‐Term Survival in “Low‐Risk” Adults

Background We sought to establish whether cardiorespiratory fitness had important implications for long-term cardiovascular risk among individuals classified as low risk by the Framingham Risk Score (10-year coronary heart disease risk <10%). Prognostic factors of long-term cardiovascular risk are needed for low-risk subjects who make up the largest percentage of the US population. Methods and Results The study population was composed of men and women, 30 to 50 years of age, who had a baseline medical exam at the Cooper Clinic, Dallas, TX, between 1970 and 1983. Eligible individuals were defined as at low risk for coronary heart disease by Framingham Risk Score at the time of study entry and had no history of diabetes (n=11 190). Cardiorespiratory fitness was determined by maximum graded exercise treadmill tests. Over an average 27±2-year period, 15% of low-fit (quintile 1) compared to 6% of high-fit (quintile 5) individuals died (P<0.001). A 1–metabolic equivalent level increase in baseline fitness was associated with an 11% reduction in all-cause deaths and an 18% reduction in deaths due to cardiovascular disease (CVD) after adjustment for age, sex, body mass index, systolic blood pressure, total cholesterol, blood glucose levels, smoking, and early family history of coronary disease. There was an incremental decrease in CVD risk with increasing fitness quintile, such that the high fit had the lowest adjusted 30-year CVD mortality rate (hazard ratio 0.29, 95% CI: 0.16–0.51) compared to the low fit. Conclusions Cardiorespiratory fitness is associated with a significant reduction in long-term CVD among individuals identified as low risk by Framingham Risk Score. These data suggest that preventive lifestyle interventions geared to optimize cardiorespiratory fitness, even among a “low-risk” subset, should be considered to improve CVD-free survival. (J Am Heart Assoc. 2012;1:e001354 doi: 10.1161/JAHA.112.001354.)

MEDICAL EXAMINATION AND ELECTROCARDIOGRAPHIC ANALYSIS OF ELITE DISTANCE RUNNERS

Much has been written about the electrocardiograms (ECG) of athletes. Abnormalities simulating organic heart disease often occur in apparently healthy, young, highly conditioned individuals who would seem to have excellent cardiovascular function, and be unlikely to have significant cardiovascular abnormalities.l-S Some of these ECG abnormalities are physiologically reasonable and explainable as a result of the training process (bradycardia, increased precordial R wave voltage, increased PR interval); others are more difficult to explain physiologically. This current study is particularly enlightening for the following reasons: The individuals studied, all world class middle-long distance or marathon run-

Age- and sex-based nomograms from coronary artery calcium scores as determined by electron beam computed tomography

We present data for 18,785 patients undergoing electron beam computed tomography, dividing them by sex and age (using 5-year age increments) to determine coronary artery calcium scores representing the 50th and 75th percentiles for each group. Because risk stratification is an integral part of determining therapies for coronary artery disease, age- and sex-based scores may be more clinically useful than total coronary artery calcium scores alone.

Incidental detection of preclinical renal tumors with electron beam computed tomography: report of 26 consecutive operated patients.

Purpose The purpose of this work was to describe the positive predictive value of electron beam CT (EBCT) for diagnosis of solid renal tumors. Method Among 11,932 consecutive patients undergoing screening EBCT, 27 cases met EBCT criteria for solid renal tumors. Twenty-six of 27 patients underwent surgery. Results Surgical pathology identified 25 solid renal tumors and 1 adrenal hemorrhage with thrombus. Twenty tumors were classified as T1N0M0, one was T2N0M0, and one was T3aN0M0. All tumor patients are clinically well at 1–41 months (mean 17 months) postoperatively. None of the patients had clinical signs or symptoms characteristic of renal malignancy. Conclusion EBCT is an effective tool for detection of solid renal tumors in a healthy outpatient population (positive predictive value 0.96). The detection rate is low [0.2% (26/11,932) at our facility] in patients undergoing EBCT for other indications. The cost-effectiveness and sensitivity of this technique for solid renal tumor detection among various populations remain to be determined.

Risk of mortality increases with increasing number of abnormal non-ST parameters recorded during exercise testing.

Background Abnormal non-ST segment treadmill parameters are associated with an increased mortality risk. Such measures include fitness, resting heart rate (HR), chronotropic incompetence, and HR recovery. However, whether there is an additive association among these parameters and the risk of mortality is unknown. Design Prospective observational registry study. Methods We assessed the risk of cardiovascular and all-cause mortality in 25 642 individuals as an additive function of the number of these parameters. Abnormal responses were defined as follows: abnormal resting HR as a HR ≥ 80 bpm, abnormal fitness as an adjusted fitness level in the lowest 20%, chronotropic incompetence as an inability to achieve at least 80% of the predicted HR reserve, and abnormal HR recovery as an HR decline less than 12bpm 1 min after exercise. Results During 7.2 years of follow-up, 392 participants died, with 94 from cardiovascular causes. Each parameter was significantly associated with all-cause and cardiovascular mortality (P [ 0.01) after adjustment for cardiovascular risk factors. There was a significant trend between both all-cause or cardiovascular mortality and the number of abnormal parameters (P [0.05). Conclusion There is a continuum of risk as the number of abnormal parameters increases, suggesting that it may be important to determine their presence and number during exercise testing.