Exercise-induced silent myocardial ischemia and future cardiac events in healthy, sedentary, middle-aged and older men

Prognostic value of high sensitive C-reactive protein in subjects with silent myocardial ischemia

OBJECTIVES

The aim of this study was to evaluate the prognostic value of high sensitive C-reactive protein (CRP) in subjects with silent myocardial ischemia (SMI).

DESIGN

In total, 678 healthy men and women aged 55 to 75 years with no history of cardiovascular disease or stroke were included. High-sensitive CRP and 48-hour ambulatory ECG monitoring were performed. The primary endpoint was the combined endpoint of death and myocardial infarction.

RESULTS

The median follow-up time was 76 months. Seventy-seven subjects (11.4%) had SMI. The combined endpoint occurred in 26% of the subjects with SMI and 14% of the subjects without SMI (P = .005). SMI had a poor prognosis in the group with an elevated CRP ≥ 3.0 μg/mL (hazard ratio, 3.46; 95% confidence interval, 1.67-7.16; P = .001) compared with the group of subjects with SMI and a low CRP <3.0 μg/mL (hazard ratio, 1.37; 95% confidence interval, 0.63-2.98; P = .54).

CONCLUSIONS

In apparently healthy subjects, a low level of CRP <3.0 μg/mL selects a low-risk subgroup, despite the presence of SMI.

Cardiovascular risk evaluation and prevalence of silent myocardial ischemia in subjects with asymptomatic carotid artery disease

Introduction:

Silent ischemia is an asymptomatic form of myocardial ischemia, not associated with angina or anginal equivalent symptoms, which can be demonstrated by changes in ECG, left ventricular function, myocardial perfusion, and metabolism. The aim of this study was to evaluate the prevalence of silent myocardial ischemia in a group of patients with asymptomatic carotid stenosis.

Methods:

A total of 37 patients with asymptomatic carotid plaques, without chest pain or dyspnea, was investigated. These patients were studied for age, sex, hypertension, diabetes, dyslipidemia, smoking, and family history of cardiac disease, and underwent technetium-99 m sestamibi myocardial stress-rest scintigraphy and echo-color Doppler examination of carotid arteries.

Results:

A statistically significant relationship (P = 0.023) was shown between positive responders and negative responders to scintigraphy test when both were tested for degree of stenosis. This relationship is surprising in view of the small number of patients in our sample. Individuals who had a positive scintigraphy test had a mean stenosis degree of 35% ± 7% compared with a mean of 44% ± 13% for those with a negative test. Specificity of our detection was 81%, with positive and negative predictive values of 60% and 63%, respectively.

Conclusion:

The present study confirms that carotid atherosclerosis is associated with coronary atherosclerosis and highlights the importance of screening for ischemic heart disease in patients with asymptomatic carotid plaques, considering eventually plaque morphology (symmetry, composition, eccentricity or concentricity of the plaque, etc) for patient stratification.

Is an exercise tolerance test indicated before beginning regular exercise? A decision analysis

BACKGROUND AND OBJECTIVE

The present study, using a decision analysis, evaluates whether an exercise tolerance test (ETT) is indicated before initiating regular physical activity to reduce the risk of sudden death during exercise training.

DESIGN

The study encompasses a decision tree, Monte Carlo simulation, and utility analysis for adults at low to high risk for coronary disease, with a time horizon of five years, with or without routine ETT screening before initiating physical activity.

MEASURES

Mortality in Monte Carlo simulation; expected values in utility analysis.

RESULTS

Routine screening decreases mortality in intermediate to high-risk populations but not in low-risk persons. At all risk levels, the number of exercise-induced deaths prevented is less than the added number of deaths from angiography. Utility analysis indicates inferiority of routine screening, regardless of risk. Personal preferences (perceived stigma from having coronary disease and perceived benefit of regular exercise on quality of life) have a strong influence on the optimal choice.

CONCLUSION

Routine screening before initiating regular exercise is not recommended for the purpose of reducing the risk of sudden death during exercise training.

A walking program's attenuation of cardiovascular reactivity in older adults with silent myocardial ischemia

Silent myocardial ischemia (SI) has been linked to increased risk of future coronary events. Enhanced systolic and diastolic blood pressure (SBP and DBP, respectively) and heart-rate (HR) reactions to stress (cardiovascular reactivity [CVR]) have been associated with greater severity of SI and are related prospectively to coronary-artery-disease endpoints. The authors examined the potential attenuating effects of 6 months of walking (aerobic exercise) versus control on CVR to three laboratory stressors in 25 older adults with exercise-induced SI. Maximal aerobic capacity was significantly improved by 12% for the exercise group and decreased by 8% for controls (p < .001). Groups had similar biomedical profiles pre- and postintervention. Walkers had significantly reduced DBP reactivity (pre, 12 +/- 2; post, 4 +/- 2 mm Hg) compared with controls (pre, 10 +/- 2; post, 11 +/- 2 mm Hg; p = .05), but no differences between groups were found for SBP or HR reactivity. These findings are the first to suggest that increased physical activity (via walking) can attenuate BP reactivity to emotional stressors in apparently healthy older adults with SI.

Reviewing myocardial silent ischemia: specific patient subgroups

Silent myocardial ischemia (SMI) is a relatively common, yet poorly understood, clinical entity. The most accurate means of detecting SMI and the precise treatment endpoints remain unclear. However, the presence of SMI correlates with the likelihood of future adverse cardiac events. Evidence suggests that patients at high risk of severe cardiac ischemia, even with the absence of symptoms, derive the greatest benefit from an aggressive diagnostic and therapeutic approach. This paper is giving a detailed review of SMI in regards to specific patient subgroups, i.e. populations with diabetes mellitus, hypertension, elderly patients, post-revascularization patients, women, the suggested screening procedures for each subgroup, as well as the emersion of new markers for the selection of high-risk patients for screening.

Prevalence and prognostic significance of daily-life silent myocardial ischaemia in middle-aged and elderly subjects with no apparent heart disease

AIMS

We aimed to determine the prevalence and prognostic significance of daily-life silent myocardial ischaemia (SMI) in healthy middle-aged and elderly subjects with no previous heart disease.

METHODS AND RESULTS

Six hundred and seventy-eight healthy men and women between 55 and 75 years of age and with no history of cardiovascular disease or stroke were included. Baseline examinations included physical examination, fasting laboratory testing, and 48 h ambulatory electrocardiogram monitoring. An episode of ischaemia was defined by a down-sloped or horizontal ST depression of at least 1 mm at a duration of at least 1 min. Seventy-seven subjects (11.4%) had SMI. All participants were followed for up to 5 years. In 77 subjects with SMI, 16 (20.7%) had an event (death or myocardial infarction). In 601 subjects without SMI, 50 (8.3%) had an event. The hazard ratios for SMI in relation to cardiac and combined events after correction for conventional risk factors were 3.1 [(1.24-7.97), P=0.016] and 1.97 [(1.06-3.69), P=0.033], respectively.

CONCLUSION

SMI as detected by Holter monitoring was detected in 11.4% of these subjects and was associated with more than three-fold increase in the cardiac event rate after correction for risk factors, implying that this test could be used to identify high-risk individuals among these subjects.

When to Stress Over Triptans: A Markov Analysis of Cardiovascular Risk in Migraine Treatment

BACKGROUND

Migraines affect 10% of the U.S. population and the episodes are frequently associated with significant disability. Triptans, 5HT1 receptor agonists, can be highly effective in treating pain and reducing disability. However, reports of cardiac events associated with triptan ingestion have led to concerns about its use in the face of possible cardiac disease.

OBJECTIVE

Should a patient without known cardiovascular disease (CAD) and moderately severe to severe migraines undergo cardiovascular testing prior to the initiation of triptan therapy?

DESIGN

A Markov model of migraine and cardiac disease using DATA 4.0. Three strategies were compared: (1) use triptans without further evaluation (TREAT); (2) test, then treat if negative (TEST); and (3) avoid triptans (NOTRIPTAN). Triptans were prohibited if a cardiac event occurred.

DATA

Model inputs were derived from the literature and subjected to sensitivity analyses across all possible values.

TIME HORIZON

Markov cycle is 1 week.

OUTCOMES

The primary outcomes of interest were quality-adjusted life expectancy, in years (QALYs) and the impact of various cardiovascular risk levels on the preferred strategy.

RESULTS

For the base case results were TREAT 19.4 QALYs, TEST 19.2, NOTRIPTAN 19.1. When altering CAD probability: TREAT dominated from 0 to 87%, TEST 87% to 97%, and NOTRIPTAN above 97%. Results were robust during sensitivity analyses.

CONCLUSIONS

This analysis suggests that even for individuals with a relatively high risk of CAD it is not beneficial to perform cardiac testing, nor to avoid triptans. The exact level of cardiac risk at which testing should be considered is probably at or above 87%.

Association of exercise-induced, silent ST-segment depression with the risk of stroke and cardiovascular diseases in men

BACKGROUND AND PURPOSE

There are few if any data on the prognostic importance of silent myocardial ischemia during exercise with regard to the risk of stroke and cardiovascular diseases (CVDs) among asymptomatic men. In this prospective study, we investigated the relation of silent myocardial ischemia and the risk of stroke and CVD death in men with and without conventional risk factors.

METHODS

The study sample included 1726 middle-aged men with no history of stroke, coronary heart disease, or atrial fibrillation at baseline. Silent myocardial ischemia was defined as a horizontal or downsloping ST-segment depression (>or=1 mm) during exercise electrocardiography. A total of 86 CVD-related deaths and 78 strokes occurred during an average follow-up of 10 years.

RESULTS

Men with silent ischemia during exercise had a 3.5-fold increased risk of CVD death and a 2.2-fold increased risk of stroke compared with men without silent ischemia, after adjusting for conventional risk factors. Silent ischemia during exercise was associated with a 3.8-fold (95% confidence interval [CI], 1.5 to 9.5) increased risk for CVD in smokers, a 3.9-fold (95% CI, 2.1 to 7.3) increased risk in hypercholesterolemic subjects, a 3.6-fold (95% CI, 1.9 to 6.8) increased risk in the hypertensives, and 3.8-fold (95% CI, 2.0 to 7.1) increased risk in overweight men. The respective relative risks for stroke were 3.8 (95% CI, 1.1 to 12.5), 3.5 (95% CI, 1.7 to 7.4), 3.4 (95% CI, 1.6 to 7.1), and 2.9 (95% CI, 1.4 to 6.1).

CONCLUSIONS

Exercise-induced silent myocardial ischemia is an important indicator of increased risk of stroke and CVD in men with other risk factors, such as smoking, hypercholesterolemia, hypertension, and being overweight.

Exercise-induced silent myocardial ischemia and coronary morbidity and mortality in middle-aged men

OBJECTIVES

We investigated the prognostic significance of exercise-induced silent myocardial ischemia in both high and low risk men with no prior coronary heart disease (CHD).

BACKGROUND

Silent ischemia predicts future coronary events in patients with CHD, but there is little evidence of its prognostic significance in subjects free of CHD.

METHODS

We investigated the association of silent ischemia, as defined by ST depression during and after maximal symptom-limited exercise test, with coronary risk in a population-based sample of men with no prior CHD followed for 10 years on average.

RESULTS

Silent ischemia during exercise was associated with a 5.9-fold (95% CI 2.3 to 11.8) CHD mortality in smokers, 3.8-fold (95% CI 1.9 to 7.9) in hypercholesterolemic men and 4.7-fold (95% CI 2.4 to 9.1) in hypertensive men adjusting for other risk factors. The respective relative risks (RRs) of any acute coronary event were 3.0 (95% CI 1.7 to 5.1), 1.9 (95% CI 1.2 to 3.1) and 2.2 (95% CI 1.4 to 3.5). These associations were weaker in men without these risk factors. Furthermore, silent ischemia after exercise was a stronger predictor for the risk of acute coronary events and CHD death in smokers and in hypercholesterolemic and hypertensive men than in men without risk factors.

CONCLUSIONS

Exercise-induced silent myocardial ischemia was a strong predictor of CHD in men with any conventional risk factor, emphasizing the importance of exercise testing to identify asymptomatic high risk men who could benefit from risk reduction and preventive measures.

Prevention of coronary heart disease. Part II. Secondary prevention, detection of subclinical disease, and emerging risk factors

The prevention of CHD should be a major priority among primary care physicians and subspecialists who have any dealing with the cardiovascular system. There is ample evidence from epidemiologic studies for the impact of specific risk factors on CHD events. There is also ample evidence from observational studies and clinical trials that interventions of lifestyle and pharmacologic therapy can decrease morbidity and mortality from CHD before or after the first event. It behooves the physician who wishes to practice good medicine to understand the pathophysiologic roles of the risk factors and the evidence from epidemiologic studies and clinical trials for their association with cardiovascular disease. It is important to determine the efficacy of interventions, both lifestyle and pharmacologic, in modifying CHD risk. To be effective in doing so, the practicing physician has to have the motivation to determine target goals for risk factor modification in each patient, to understand the patient's own motivations in modifying risk factors, and to define clearly with the patient the expectations of such interventions. Although there are guidelines for risk factor modification in modification of cholesterol and in hypertension, the periodic renewal of these guidelines reflects the changing concepts of risk and its modification. A cardiovascular risk factor intervention categorization is presented in Table 12. The physician must be convinced that such intervention is beneficial to the patient, cost-effective, and thus fulfills the expectations of medical practice. The practice of medicine in the evaluation and treatment of coronary heart disease has always been challenging and stimulating. The prevention of CAD disease should ultimately provide the greatest accomplishment.