Triggers of myocardial ischemia during daily life in patients with coronary artery disease: physical and mental activities, anger and smoking

OBJECTIVES

This study assessed the potency of physical and mental activities and emotions (anger and anxiety) and smoking and other substance use as proximate triggers of ischemia in patients with coronary artery disease during daily life.

BACKGROUND

Myocardial ischemia occurs during a wide variety of activities in patients with coronary artery disease, but frequency and relative potency of physical and mental activities, smoking and use of caffeine and alcohol as triggers of ischemia during daily life have not been established.

METHODS

Patients (n = 63) with coronary artery disease and evidence of out-of-hospital ischemia kept a validated structured diary of physical and mental activities and psychologic states while undergoing ambulatory electrocardiographic monitoring for 24 to 48 h.

RESULTS

Ischemia occurred most frequently during moderately intense physical and mental activities. Patients spent the largest proportion of time engaged in low intensity physical and mental activities (p < 0.05), but the likelihood of ischemia was greatest during intense physical (p < 0.0001) and stressful mental activities (p < 0.03). The percentage of time in ischemia was elevated and approximately equivalent for high intensity physical and high intensity mental activities (5%) compared with 0.2% when patients were engaged in low intensity activities. Strenuous physical activity (e.g., effortful walking, p < 0.05) and the experience of intense anger were potent ischemic triggers, and heart rates at onset of ischemia increased with the intensity of physical and mental activity and with anger. Among smokers, ischemia was more than five times as likely when patients smoked than when they did not (during 24% vs. 5% of diary entries, p < 0.0001). Coffee and alcohol consumption were also related to ischemia (p < 0.05), but this association disappeared after controlling for concurrent cigarette smoking.

CONCLUSIONS

Triggers of ischemia in patients with coronary artery disease during daily life include not only strenuous exercise, but also activities involving low levels of exertion, such as anger and smoking. Mental activities appear to be as potent as physical activities in triggering daily life ischemia. Coffee and alcohol consumption are related to ischemia only by virtue of their associations with smoking.

Triggers of angina and ST-segment depression in ambulatory patients with coronary artery disease: evidence for an uncoupling of angina and ischemia

This study evaluated daily-life physical and mental triggers of painful and painless myocardial ischemia and of anginal pain in patients with coronary artery disease (CAD) by using ambulatory electrocardiographic monitoring and a structured diary. Eighty-five percent of ambulant ischemic episodes occurred without chest pain; 66% of anginal pain reports were made in the absence of ischemic ST-segment depression. Chest pain reports in the absence of ischemia could not be attributed to "borderline" ST-segment changes. Compared with silent ischemia, painful ischemia was triggered at higher levels of physical activity (p < 0.05) and at higher levels of self-rated effort and negative emotion (p < 0.05). Painful episodes were associated with greater-magnitude ST depression (p < 0.02), but a substantial percentage of episodes with > or = 2 mm and > or = 3 mm ST depression were silent. These results reveal an uncoupling of anginal symptoms from ambulatory ischemic episodes in patients with CAD during daily life. In addition, specific activities and emotions correlate with the presence or absence of anginal symptoms as much as does the presence of ischemic ST depression. These results may have implications for antiischemic and antianginal treatment strategies.

Automated physical activity monitoring: validation and comparison with physiological and self-report measures

Physical activity can be assessed via self-report, via physiological measures such as heart rate and oxygen uptake, or via automated monitor. An electronic accelerometer-based physical activity device (Actigraph) has been reported as an improvement over other activity measurement techniques in terms of utility and accuracy. Four studies provide systematic validation and reliability testing for this device and comparisons with other techniques for assessing daily activities. In the first study, the sensitivity of the Actigraph was determined for differentiating physical activities (walking, running, stair climbing, knee bends) versus sedentary activities (reading, typing, playing video games, and performing a mental arithmetic task). Fifteen healthy adults wore the Actigraph on their wrist during activities; oxygen uptake and heart rate were simultaneously recorded. Results revealed that the Actigraph significantly differentiated between the physical activities (p < .0001) and the sedentary activities (p < .0001). Actigraph counts also correlated significantly with oxygen uptake (r = .73) and heart rate (r = .71) during physical activities (r = .46) and sedentary activities (r = .35), respectively. Test-retest reliability was very high for 12 activities (r = .98). The high level of activity differentiation and strong relationship to oxygen uptake and heart rate suggest the usefulness of this device for behavioral and biomedical studies. However, these studies also indicate that the wrist may not always be the most adequate placement for indexing rate and intensity of daily activities and that further studies are needed to determine the optimal site of monitor attachment. Advantages and disadvantages of self-report, physiological, and automated measures of activity are discussed.

Cardiovascular reactivity and mental stress-induced myocardial ischemia in patients with coronary artery disease

This report evaluates the relationships of hemodynamic reactivity and determinants of myocardial oxygen demand to myocardial ischemia during mental stress in coronary artery disease patients. Thirty-nine patients and 12 controls were studied by radionuclide ventriculography during three mental tasks (arithmetic, Stroop task, and simulated public speaking). Patients were subdivided into three groups based on the severity of ischemic wall motion responses to the mental stressors. Results revealed that systolic blood pressure (SBP) levels during the mental tasks and SBP reactivity (increases) to stress were highest for the severely ischemic group, lowest for controls, with the mild-moderate ischemic and nonischemic patients in between. Severely ischemic patients started out with lower double product (heart rate x SBP) levels, and reached higher levels during the Stroop and speech tasks. There were no reliable group effects for diastolic blood pressure, heart rate, or left ventricular end-diastolic volumes. Among severely ischemic patients, the most potent task in eliciting ischemia (the speech) was associated with higher cardiovascular levels and elicited greater heart rate, double product, and ventricular volume responses. The present data indicate a relationship between cardiovascular levels and reactivity and the magnitude of ischemia induced by mental stress.

The effects of phenylpropanolamine on human sympathetic nervous system function

Phenylpropanolamine (PPA) is a sympathomimetic agent, very similar in structure to amphetamine. In the United States, it is present in over 130 medications, primarily anorectic agents and cough and cold remedies, many available without a prescription. The effects of PPA on blood pressure (BP) remain controversial and its mechanisms of action unknown. We studied acute (1 and 2 hours) and 2-week effects of a daily dose of 75 mg of sustained release PPA administered to 14 normal volunteers. Measurements of heart rate, BP, and plasma catecholamines (CA) were made with the subject in the supine and standing positions, and upon gripping a hand dynamometer for 5 minutes. Although systolic BP across all postures and sampling times was significantly higher when subjects were taking PPA in comparison to placebo (F = 5.95, p = 0.03), in no subject did the increase in BP reach hypertensive or clinically significant levels and no substantial changes in CA levels were found. Our study population was relatively young and normotensive; even such a small BP increase may pose greater problems for hypertensive, obese subjects likely to be users of diet aids. Strenuous isometric exercise did not cause any greater increase in BP or CA after subjects took PPA versus placebo. PPA blood levels 24 hours after the last of 14 daily doses were similar to levels 1 and 2 hours after an initial dose. We conclude from these data that recommended doses of PPA have only minimal sympathetic nervous system (SNS) and cardiovascular effects in young, healthy, normotensive populations at the times and dose studied.

Some cautions for research on personality and health

This article comments on three conceptualizations of the relationship between personality and disease as they relate to the papers in this issue. Despite the sophistication and promise of recent research in this area, conceptual and methodological difficulties present in earlier psychosomatic research have persisted. In this area, robust and convincing associations between traits and disease remain largely elusive, and stable, valid measures of psychological factors are relatively rare. In addition, the mechanisms relating behavior to health are sometimes sketchy or overstated. We suggest that the most productive research strategies will focus on mechanisms linking behavior to health, rather than merely correlating traits with measures of disease. Needed are continued close attention to these pitfalls by researchers as well as the maintenance of a critical attitude by readers.