Ray W. Squires

Impact of Cardiac Rehabilitation on Mortality and Cardiovascular Events After Percutaneous Coronary Intervention in the Community

Background— Although numerous studies have reported that cardiac rehabilitation (CR) is associated with reduced mortality after myocardial infarction, less is known about its association with mortality after percutaneous coronary intervention. Methods and Results— We performed a retrospective analysis of data from a prospectively collected registry of 2395 consecutive patients who underwent percutaneous coronary intervention in Olmsted County, Minnesota, from 1994 to 2008. The association of CR with all-cause mortality, cardiac mortality, myocardial infarction, or revascularization was assessed with 3 statistical techniques: propensity score–matched analysis (n=1438), propensity score stratification (n=2351), and regression adjustment with propensity score in a 3-month landmark analysis (n=2009). During a median follow-up of 6.3 years, 503 deaths (199 cardiac), 394 myocardial infarctions, and 755 revascularization procedures occurred in the study subjects. Participation in CR, noted in 40% (964 of 2395) of the cohort, was associated with a significant decrease in all-cause mortality by all 3 statistical techniques (hazard ratio, 0.53 to 0.55; P<0.001). A trend toward decreased cardiac mortality was also observed in CR participants; however, no effect was observed for subsequent myocardial infarction or revascularization. The association between CR participation and reduced mortality rates was similar for men and women, for older and younger patients, and for patients undergoing elective or nonelective percutaneous coronary intervention. Conclusions— We found that CR participation after percutaneous coronary intervention was associated with a significant reduction in mortality rates. These findings add support to published clinical practice guidelines, performance measures, and insurance coverage policies that recommend CR for patients after percutaneous coronary intervention.

Exercise Training and Cardiac Rehabilitation in Primary and Secondary Prevention of Coronary Heart Disease

Substantial data have established a sedentary lifestyle as a major modifiable risk factor for coronary heart disease (CHD). Increased levels of physical activity, exercise training, and overall cardiorespiratory fitness have provided protection in the primary and secondary prevention of CHD. This review surveys data from observational studies supporting the benefits of physical activity, exercise training, and overall cardiorespiratory fitness in primary prevention. Clearly, cardiac rehabilitation/secondary prevention (CRSP) programs have been greatly underused by patients with CHD. We review the benefits of CRSP programs on CHD risk factors, psychological factors, and overall CHD morbidity and mortality. These data support the routine referral of patients with CHD to CRSP programs. Patients should be vigorously encouraged to attend these programs.

Prevention of cardiovascular disease: Of what value are risk factor modification, exercise, fish consumption, and aspirin therapy?

PreviewAlthough on the decline, cardiovascular disease remains a major present and future threat to health in the United States. Family physicians, internists, and cardiologists face the dual challenge of impeding its progression and preventing its development. Intervention in modifiable risk factors, regular exercise, increased fish consumption, and daily aspirin therapy may each have an important role to play. In this article, Dr Lavie and coauthors discuss in detail the possible benefits of each.

Prognostic significance of exercise-induced systemic hypertension in healthy subjects

Exercise hypertension has been suggested to predict future resting hypertension, but its significance in terms of cardiovascular risk has not been defined. To assess the prognostic significance of exercise hypertension, 150 healthy, asymptomatic subjects with normal resting blood pressures and exercise systolic blood pressures > or =214 mm Hg (i.e., >90th percentile) on Bruce treadmill tests were identified retrospectively and age- and gender-matched with subjects with exercise systolic blood pressures of 170 to 192 mm Hg (40th to 70th percentiles). Subjects were contacted by survey a mean of 7.7+/-2.9 years after the index treadmill test. The survey response rate was 93%. There were 12 deaths, including 8 in the exercise hypertension group. A major cardiovascular event, defined as cardiovascular death, myocardial infarction, stroke, coronary angioplasty, or coronary bypass graft surgery occurred in 5 controls and 10 subjects with exercise hypertension. At follow-up, 13 controls and 37 subjects with exercise hypertension were now diagnosed as having resting hypertension. In multivariate analysis, exercise hypertension was not a significant predictor for death or any individual cardiovascular event, but was for total cardiovascular events and new resting hypertension. The multivariate risk ratio for exercise hypertension was 3.62 (p = 0.03) in predicting a major cardiovascular event. Other significant predictors included body mass index and age. For predicting new resting hypertension, the multivariate odds ratio for exercise hypertension was 2.41 (p = 0.02). These data suggest that exercise hypertension carries a small but significant risk for major cardiovascular events in healthy, asymptomatic persons with normal resting blood pressures.

Peak exercise blood pressure stratified by age and gender in apparently healthy subjects

OBJECTIVE To determine the peak blood pressure responses during symptom-limited exercise in a large sample of apparently healthy subjects, including both men and women over a wide range of ages. DESIGN We retrospectively studied the blood pressure response during maximal treadmill exercise testing with use of the Bruce protocol in apparently healthy subjects. MATERIAL AND METHODS Peak exercise blood pressures in 7,863 male and 2,406 female apparently healthy subjects who underwent a screening treadmill exercise test with the Bruce protocol between 1988 and 1992 were analyzed by age and gender. RESULTS In this large referral population of apparently healthy subjects, peak exercise systolic and diastolic blood pressures and delta systolic blood pressure (rest to peak exercise) were higher in men than in women and were positively associated with age. In men, the 90th percentile of systolic blood pressure increased from 210 mm Hg for the age decade 20 to 29 years to 234 mm Hg for ages 70 to 79 years; the corresponding increase among women was from 180 mm Hg to 220 mm Hg. Delta diastolic blood pressure also increased with advancing age. The difference in peak and delta systolic blood pressures between men and women seemed to decrease after age 40 to 49 years. Exercise hypotension, defined as peak exercise systolic pressure less than rest systolic pressure, occurred in 0.23% of men and 1.45% of women and was not significantly related to age. CONCLUSION Overall, peak exercise systolic and diastolic, as well as delta systolic, blood pressures were higher in men than in women and increased with advancing age. The reported data will enable clinicians to interpret more accurately the significance of peak exercise blood pressure response in a subject of a specific age and gender and will allow investigators to define exercise hypertension in statistical terms stratified by age and gender.

Prognostic importance of weight loss in patients with coronary heart disease regardless of initial body mass index

Background Recently, mild elevations in body mass index (BMI) have been related to better outcomes in patients with coronary heart disease. Our aim was to determine whether patients with coronary heart disease who are participating in cardiac rehabilitation would have improved outcomes if they lost weight and whether this would depend on initial BMI. Methods This is a prospective cohort study of 377 consecutive patients enrolled at a cardiac rehabilitation program, aged 30–85 years with a mean follow-up of 6.4 ± 1.8 years. We measured total mortality, acute cardiovascular events (fatal and nonfatal myocardial infarction, fatal and nonfatal stroke, emergent revascularization in the setting of unstable angina, and hospitalization for congestive heart failure) and a composite outcome (mortality + acute cardiovascular events). Statistical testing used Cox Proportional Hazards Regression. Results On average, the weight loss group (n = 220) lost 3.6 ± 4.1 kg, and the nonweight loss group (n = 157) gained 1.5 ± 1.4 kg (P< 0.0001). The rate of the composite outcome was 24% (53/220) in those who did lose weight versus 37% (58/157) in those who did not lose weight. Weight loss was significantly associated with lower rate of the composite outcome after adjustment for age, sex, smoking, dyslipidemia, diabetes, hypertension, myocardial infarction, and obese status [hazard ratio (HR) = 0.62; P = 0.018]. Subgroup analysis showed that patients who lost weight had favorable outcomes both in patients with BMI ≤25 (HR = 0.32; P = 0.035) and those with BMI ≥ 25 kg/m2 (HR = 0.64; P = 0.032). Conclusions Weight loss in cardiac rehabilitation is a marker for favorable long-term outcomes, regardless of initial BMI.

Combined effect of cardiorespiratory fitness and adiposity on mortality in patients with coronary artery disease

BACKGROUND High cardiorespiratory fitness and body mass index (BMI) are associated with decreased mortality in patients with coronary artery disease. Our objective was to determine the joint impact of fitness and adiposity measures on all-cause mortality in this subgroup. METHODS Coronary artery disease patients (n = 855) enrolled in the Mayo Clinic cardiac rehabilitation program from 1993 to 2007 were included. Fitness levels were determined by cardiopulmonary exercise testing. Patients were divided into low and high fitness by sex-specific median values of peak oxygen consumption and total treadmill time. Adiposity was measured through BMI and waist-to-hip ratio (WHR). RESULTS There were 159 deaths during 9.7 ± 3.6 years of mean follow-up. After adjusting for potential confounding factors, low fitness, shorter treadmill time, low BMI, and high WHR were significantly associated with increased mortality. Using low WHR-high fitness group as reference, significantly increased mortality was noted in low WHR-low fitness (hazard ratio 4.2, 95% CI, 1.8-9.8), centrally obese-high fitness (2.3, 1.0-5.4), and centrally obese-low fitness (6.1, 2.7-13.6) groups. Overweight-high fitness (2.2, 0.63-7.4), obese-high fitness (3.2, 0.88-11.4), and obese-low fitness (3.3, 0.96-11.4) subjects did not have a significantly different mortality as compared with the reference group of normal weight-high fitness subjects, whereas normal weight-low fitness (9.6, 2.9-31.8) and overweight-low fitness (6.8, 2.1-22.2) groups had significantly increased mortality. CONCLUSIONS Low fitness and central obesity were independently and cumulatively associated with increased mortality in coronary artery disease patients attending cardiac rehabilitation. The association of BMI with mortality is complex and altered by fitness levels.

Comparison of dual-chamber pacing versus septal myectomy for the treatment of patients with hypertrophic obstructive cardiomyopathy : A comparison of objective hemodynamic and exercise end points

Abstract OBJECTIVES The purpose of this study was to compare the treatment effects of septal myectomy with dual-chamber pacing in patients with hypertrophic obstructive cardiomyopathy (HOCM). BACKGROUND The optimal treatment for symptomatic patients with drug-refractory HOCM is unknown. Both dual-chamber pacing and surgical myectomy may result in subjective symptom improvement. However, no direct comparisons with objective end points have been reported. METHODS Thirty-nine patients with symptomatic HOCM were analyzed in this concurrent cohort study. Twenty patients underwent surgical myectomy, and 19 received dual-chamber pacemakers based on patient preference. These patients had prospective baseline and follow-up evaluations including physician assessment, echocardiography and standardized metabolic treadmill exercise testing. RESULTS Baseline symptom status, left ventricular outflow tract gradients, exercise times and maximal oxygen consumption peak were similar between the two groups. Left ventricular outflow gradient was reduced from 76 ± 57 to 9 ± 17 mm Hg (p = 0.0001) after myectomy, and from 77 ± 61 to 55 ± 39 mm Hg (p = 0.07) after pacing (p = 0.02 for comparison with myectomy). Ninety percent of myectomy patients experienced symptomatic improvement as compared with 47% in the pacing group. Exercise duration increased significantly from 6.6 ± 2.8 to 8.7 ± 3.0 min (p = 0.0003) after myectomy compared with a change from 6.4 ± 2.1 to 7.0 ± 2.2 min (p = NS) in the pacing group. Maximal oxygen consumption increased from 19.4 ± 6.4 to 22.2 ± 6.5 ml/kg/min after myectomy (p = 0.004), whereas the pacing group did not experience any significant change (19.6 ± 6.5 vs. 20.1 ± 6.5 ml/kg/min, p = NS). CONCLUSIONS Surgical myectomy and dual-chamber pacing improve subjective measures of functional status in patients with symptomatic HOCM. In this nonrandomized study, myectomy offered greater reduction in left ventricular outflow tract gradients and larger improvements in objective measures of patient symptoms and functional status when compared with dual-chamber pacing.

Niacin-Induced Hepatitis: A Potential Side Effect With Low-Dose Time-Release Niacin

Hepatitis developed in five patients who were taking low dosages (3 g/day or less) of time-release niacin. In four of the five patients, clinical symptoms of hepatitis developed after the medication had been taken for a relatively short time (2 days to 7 weeks). This manifestation of hepatotoxicity seems to differ from that previously reported in association with use of crystalline niacin, which occurred with high dosage and prolonged usage of the medication. In view of the recent increased frequency of prescribing niacin for the treatment of hyperlipidemia, physicians should be aware of the potential for hepatotoxicity with even low-dose and short-term use of time-release niacin.

Aerobic capacity during acute exposure to simulated altitude, 914 to 2286 meters.

In order to systematically assess the effects of acute exposure to moderate hypoxia on aerobic capacity (VO2max), 12 men (regular participants in recreational distance running) performed six treadmill-graded exercise tests (GXTs) in a hypobaric chamber. GXTs 1 and 6 were performed at ambient (control) altitude (362 m, barometric pressure = 730 mmHg). GXTs 2-5 were administered during 1-2 h of exposure to barometric pressures of 681, 656, 632, and 574 mmHg simulating altitudes of 914, 1219, 1524, and 2286 m, respectively, with the order of presentation randomized and blinded for each subject. The mean VO2max for GXTs 1 and 6 (control altitude) were essentially identical with a test-retest correlation of r = 0.92. During peak exercise, HR max was unchanged by hypoxia, while VO2max was significantly lower than the control by 4,8, 6.9, and 11.9% at 1219, 1524, and 2286 m, respectively. SaO2@max percent during maximal exercise was significantly reduced from the control by 3.5, 3.6, 7.0, and 11.6% at 914, 1219, 1524, and 2286 m, respectively. It was concluded that VO2max, in physically well-conditioned persons living at 362 m, is reduced during acute exposure to 1219 m and above.