Exercise-induced silent ischemia: age, diabetes mellitus, previous myocardial infarction and prognosis.

The purposes of this study were 1) to determine the prognosis of silent ischemia in an unselected group of patients referred for exercise testing, and 2) to assess whether age or the presence of myocardial infarction or diabetes mellitus influences the prevalence of silent myocardial ischemia during exercise testing. The design was retrospective, with a 2 year mean follow-up period. The study group consisted of 1,747 predominantly male in-patients and outpatients referred for exercise testing at a 1,200 bed Veterans Administration hospital. The main result was that the mortality rate was significantly greater (p = 0.02) among patients with abnormal ST segment depression than in patients without ST depression. The presence or absence of angina pectoris during exercise testing was not significantly related to death. The prevalence of silent ischemia was not significantly different among patients categorized according to myocardial infarction or diabetes mellitus status, but was directly related to age. It is concluded that, in patients with an ischemic ST response to exercise testing, the presence or absence of angina pectoris during the test does not alter the risk of death. The prevalence of silent ischemia during exercise testing is not statistically different among patients with recent, past or no myocardial infarction or with insulin-dependent or noninsulin-dependent diabetes mellitus.

Maximal exercise testing and gas exchange in patients with chronic atrial fibrillation.

To evaluate the response of patients with chronic atrial fibrillation to exercise, 50 men (mean age 65 +/- 8 years) with atrial fibrillation underwent a maximal exercise test using respiratory gas exchange techniques. Patients were classified by the presence (n = 29) or absence ("lone atrial fibrillation," n = 21) of underlying heart disease. Responses were evaluated at a standard submaximal work load (3.0 mph, [4.8 km/h] 0% grade), at the gas exchange anaerobic threshold and at maximal exercise. For all 50 patients, the mean maximal oxygen uptake was 20.6 ml/kg per min, which approximates 85% of the aerobic capacity predicted for age-matched normal individuals. Patients with lone atrial fibrillation demonstrated normal exercise capacity in contrast to patients with atrial fibrillation and known heart disease (22.7 +/- 5 versus 19.1 +/- 5.0 ml/kg per min, p less than 0.05). The mean maximal heart rate (176 +/- 30 beats/min) was approximately 20 beats/min higher than that expected for age, was extremely variable and accounted for only 8% of the variance in maximal oxygen uptake. Maximal heart rate in subjects with lone atrial fibrillation was higher than that of subjects with atrial fibrillation and known heart disease (189 +/- 32 versus 166 +/- 24 beats/min, p less than 0.01). Stepwise regression analysis revealed that maximal systolic blood pressure accounted for 19% of the variance in maximal oxygen uptake (VO2 max), suggesting that systolic function is an important determinant of exercise performance in atrial fibrillation.(ABSTRACT TRUNCATED AT 250 WORDS)

Anomalous origin of the circumflex coronary artery in association with the right superior septal artery.

The presence of anomalous coronary arteries is observed infrequently during routine coronary angiography. However, their identification is crucial to the management of the patient with associated coronary artery disease. A case is described in which concomitant anomalous origin of the circumflex coronary artery from the right coronary artery, and a right superior septal coronary artery with a separate ostium occurred in association with severe three-vessel coronary artery disease requiring bypass graft surgery. Clues to the presence of the anomalous vessels were (1) their visualization during left ventriculography and (2) their presence or absence during injection of the normally originating vessels. This particular association of anomalous vessels was previously unreported.

The effect of cardioversion on maximal exercise capacity in patients with chronic atrial fibrillation.

To evaluate the effect of cardioversion on exercise capacity, 11 male patients (59 +/- 8 years) with chronic atrial fibrillation underwent maximal exercise testing using gas exchange techniques before and after successful cardioversion to normal sinus rhythm. Testing was conducted 1 day prior to and a mean of 39 (range 10 to 95) days following cardioversion. Heart rate, blood pressure, and respiratory gas exchange responses were evaluated at rest, at a standard submaximal workload (3.0 mph/0% grade), at the gas exchange anaerobic threshold, and at maximal exertion. Cardioversion resulted in a mean decrease in resting heart rate of 37 beats/min (113 +/- 16 versus 76 +/- 10 beats/min, p less than 0.001). While mean heart rate was approximately 50 beats/min lower following cardioversion at both submaximal stages of exercise p less than 0.001), oxygen uptake was not different. At maximal exercise, heart rate was markedly reduced (192 +/- 24 to 144 +/- 21 beats/min, p less than 0.001) and maximal oxygen uptake was higher (1.86 +/- 0.5 to 2.06 +/- 0.5 L/min, p less than 0.05) after cardioversion. In addition, an improved efficiency of ventilation was observed at exercise levels exceeding 60% of maximal oxygen uptake.