The relation between myocardial ischemia and the ejection fraction response to exercise in patients with normal or abnormal resting left ventricular function

Orthostatic Hypotension and Risk of Clinical and Subclinical Cardiovascular Disease in Middle-Aged Adults

Background

Although orthostatic hypotension (OH) is a well‐recognized manifestation of neuropathy and hypovolemia, its contribution to cardiovascular disease (CVD) risk is controversial.

Methods and Results

Participants with OH, defined as a decrease in blood pressure (systolic ≥20 mm Hg or diastolic ≥10 mm Hg) from the supine to standing position, were identified during the first visit of the ARIC (Atherosclerosis Risk in Communities) Study (1987–1989) within 2 minutes of standing. All participants were followed up for the development of myocardial infarction, heart failure, stroke, fatal coronary heart disease (CHD), any CHD (combination of silent, nonfatal, and fatal CHD or cardiac procedures), and all‐cause mortality. Participants were assessed for carotid intimal thickness and plaque during the first visit. Detectable high‐sensitivity troponin T (≥5 ng/L) and elevated NT‐proBNP (N‐terminal pro‐B‐type natriuretic peptide; ≥100 pg/mL) were determined in blood collected during the second visit (1990–1992). All associations were adjusted for known CVD risk factors. In 9139 participants (57% women; 23% black; mean age, 54±5.7 years), 3% had OH. During follow‐up (median, 26 years), OH was associated with myocardial infarction (hazard ratio [HR], 1.88; 95% confidence interval [CI], 1.44–2.46), congestive heart failure (HR, 1.65; 95% CI, 1.34–2.04), stroke (HR, 1.83; 95% CI, 1.35–2.48), fatal CHD (HR, 2.77; 95% CI, 1.93–3.98), any CHD (HR, 2.00; 95% CI, 1.64–2.44), and all‐cause mortality (HR, 1.68; 95% CI, 1.45–1.95). OH was also associated with carotid intimal thickness (β, 0.05 mm; 95% CI, 0.04–0.07 mm), carotid plaque (odds ratio, 1.51; 95% CI, 1.18–1.93), detectable high‐sensitivity troponin T (odds ratio, 1.49; 95% CI, 1.16–1.93), and elevated NT‐proBNP (odds ratio, 1.92; 95% CI, 1.48–2.49).

Conclusions

OH identified in community‐dwelling middle‐aged adults was associated with future CVD events and subclinical CVD. Further research is necessary to establish a causal role for OH in the pathogenesis of CVD.

Risk stratification of patients with coronary artery disease and left ventricular dysfunction by exercise radionuclide angiography and exercise electrocardiography

BACKGROUND

The results of multicenter trials indicate that patients with left ventricular dysfunction and either three-vessel or left main coronary artery disease have improved prognosis when treated surgically.

OBJECTIVE

As part of a larger evaluation and follow-up study of coronary artery disease, the objective of this investigation was to determine whether exercise radionuclide angiography can be used, in patients with mild symptoms of coronary artery disease and left ventricular dysfunction at rest, to identify patients with three-vessel or left main coronary artery disease.

METHODS AND RESULTS

Eighty-four consecutive patients were studied with angiographically defined coronary artery disease in whom left ventricular ejection fraction at rest ranged from 20% to 40%. Patients underwent exercise electrocardiography, rest and exercise radionuclide angiography, and 24-hour electrocardiographic monitoring. There were 22 patients with one-vessel, 31 with two-vessel, 27 with three-vessel, and four with left main coronary artery disease. All but four patients had a documented history of myocardial infarction. By univariate analysis, the following parameters were related to the anatomic severity of coronary artery disease: magnitude of ST segment depression with exercise (p < 0.001), magnitude of change in ejection fraction with exercise (p < 0.005), and occurrence of angina during exercise (p < 0.005). However, because of the extensive overlap among anatomic subgroups, no single factor had both a satisfactory sensitivity and a satisfactory specificity in identifying patients with three-vessel and left main coronary artery disease. Multivariate stepwise regression analysis also failed to predict three-vessel or left main coronary artery disease satisfactorily (sensitivity 73% and specificity 73%; positive predictive accuracy 59% and negative predictive accuracy 83%). Nonetheless, this multivariate analysis provided important prognostic information. During medical therapy (mean follow-up 56 months), the patients with a high likelihood of three-vessel or left main coronary artery disease had a greater risk of death or reinfarction than had patients with a low likelihood (p < 0.05). These functional data were better than coronary anatomy alone in providing risk stratification. Four of six patients with two-vessel disease who died were classified incorrectly by the multivariate analysis in the high-likelihood group for three-vessel or left main coronary artery disease, but classified correctly as being at high risk; whereas none of the patients with three-vessel disease who were misclassified in the low-likelihood group died during medical therapy.

CONCLUSION

Although exercise radionuclide angiography in patients with minimal symptoms of coronary artery disease and left ventricular dysfunction is not precise in predicting three-vessel or left main coronary artery disease, it provides important functional information regarding subsequent prognosis during medical therapy.

Predicting severe ischemic events after uncomplicated myocardial infarction by exercise testing and rest and exercise radionuclide ventriculography

BACKGROUND

In 183 patients with uncomplicated myocardial infarction, exercise-induced angina, ST segment depression, decrease in ejection fraction, or inadequate increase in systolic blood pressure and low exercise tolerance were significantly associated with 4-year incidence of hard ischemic events.

METHODS AND RESULTS

Only the onset of both ST segment depression and a decrease in left ventricular ejection fraction with exercise was an independent predictor. ST segment depression and decrease in left ventricular ejection fraction had low sensitivity (61% and 70%) and specificity (56% and 51%) for hard ischemic events, but specificity increased to 78% when both were present. During medical therapy, 22 of 53 patients with both ST segment depression and a decrease in left ventricular ejection fraction with exercise had an ischemic event (i.e., 48.1% 4-year probability on Kaplan-Meier analysis vs 19.2% in the remaining 130 patients [p < 0.0005]).

CONCLUSIONS

Even if no single variable, derived from exercise testing, is a highly sensitive and specific predictor, specificity increases to a clinically relevant level by combining ST segment depression and a decrease in left ventricular ejection fraction with exercise, and in this way patients with recent infarction may be selected for coronary arteriography.

Assessment of left ventricular ejection fraction from technetium-99m-methoxy isobutyl isonitrile multiple-gated radionuclide angiocardiography

Abnormal left ventricular function is a diagnostic indication of cardiac disease. Left ventricular function is commonly quantified by ejection fraction measurements. A novel approach for the determination of left ventricular ejection fraction from technetium-99m-methoxy isobutyl isonitrile multiple-gated radionuclide angiocardiography is presented. Data from 23 patients, symptomatic of cardiac disease, indicate that ejection fractions determined using the radionuclide technique correlate well with contrast X-ray single-plane cineangiography (r=0.83, p<10(-6)). Data from 14 of the patients indicate favorable correlation with technetium-99m-pertechnetate gated blood pool radionuclide angiocardiography (r=0.87, p<10(-4)).

Left ventricular pressure/volume relationship in coronary artery disease

This study examined the changes during exercise in LV EF and P/V relationship (systolic blood pressure/end-systolic volume index ratio) in 287 patients. Normal range (mean +/- standard deviation) for exercise EF, exercise P/V, and the changes from rest to exercise (delta) in EF and P/V were established in 51 subjects with less than 1% probability of CAD. The results were compared to those obtained in 53 patients with normal coronary angiograms and 183 patients with angiographically proven CAD. Abnormality in either delta EF or percent delta P/V were observed in 76% of the patients with one-vessel disease and in 91% of patients with multivessel disease. Abnormalities in either delta EF or percent delta P/V were more common than delta EF alone in the total CAD group and in subgroups stratified according to the resting EF, extent of CAD, and adequacy of exercise end points. Similar results were obtained when absolute exercise EF or exercise P/V were used. Abnormalities in the percent delta P/V or delta EF were also seen in 26 of the 53 patients with normal coronary angiograms. Thus, abnormalities in the P/V relationship or EF during exercise are more common than abnormalities in the EF alone. Relative and absolute measurements provide similar results.

Radionuclide evaluation of exercise left ventricular performance in patients with coronary artery disease

Rest and exercise radionuclide angiography is a useful technique to study the cardiac adaptation during exercise in patients with coronary artery disease. Most patients with coronary artery disease have an abnormal EF response to exercise, although the magnitude of the change in EF may not correlate with the extent of coronary artery disease. The resting end-diastolic volume maybe the most important determinant of the presence and degree of left ventricular dilation during exercise in such patients. The exercise left ventricular EF improves after revascularization, but the EF response to exercise often remains abnormal. Evaluation of the regional and global left ventricular performance and the pressure-volume relationship during systole and diastole, as well as changes in these parameters after revascularization are possible. The exercise EF is also an important prognosticator in patients with known or suspected coronary artery disease.