Prognostic and predictive value of exertional hypotension in suspected coronary heart disease

Patients With Peripheral Arterial Disease With Exaggerated Pressor Response Have Greater Ambulatory Dysfunction Than Patients With Lower Pressor Response

We determined whether patients with peripheral arterial disease (PAD) who have either an exaggerated or a negative pressor response during treadmill walking have shorter peak walking time (PWT) and claudication onset time (COT) than patients with a normal pressor response, independent of comorbid conditions. A total of 249 patients were categorized to 1 of 3 groups based on systolic blood pressure (SBP) responses at 2 minutes of treadmill walking (speed = 2 mph, grade = 0%): group 1 (negative pressor response, SBP < 0 mm Hg), group 2 (normal pressor response, SBP 18 mm Hg), and group 3 (exaggerated pressor response, SBP > 18 mm Hg). After adjusting for comorbid conditions, group 3 (exaggerated) had significantly reduced COT (P = .011) and PWT (P = .002) compared to group 2 (normal), while group 1 (negative) and group 2 (normal) were not different. Patients with symptomatic PAD with an increase in SBP > 18 mm Hg after 2 minutes of treadmill walking experience claudication earlier and thus have greater ambulatory dysfunction, compared to patients with PAD with a normal pressor response, whereas patients with PAD with negative pressor response had a similar walking performance. The implication is that the magnitude of pressor response to only 2 minutes of treadmill walking can partially explain the degree of ambulatory dysfunction in patients with PAD.

ST elevation in recovery post exercise with normal coronary arteries

We present the case of a 45-year-old healthy man who successfully completed three stages of the Bruce protocol but developed inferolateral ST segment elevation in the recovery phase. The ECG change was associated with a marked drop in blood pressure. He underwent emergency coronary angiography which revealed normal coronary arteries. It is likely that post-exercise hypotension triggered coronary spasm which caused the ST segment elevation. Alternatively, coronary spasm may have been the primary event, inducing sufficient myocardial ischaemia to cause a marked drop in blood pressure. Exercise tolerance testing is often a reliable test to rule out reversible myocardial ischaemia. While the physician is focused on ischaemic changes or rhythm abnormalities developing during the exercise phase, the recovery period is just as important and requires as much vigilance. Coronary vasospasm can result in significant ST changes and haemodynamic compromise at any point during the test, and the ECG traces can be indistinguishable from a classic ST elevation myocardial infarction, as in the present case.

Exercise Blood Pressure Guidelines: Time to Re-evaluate What is Normal and Exaggerated?

Blood pressure responses to graded exercise testing can provide important diagnostic and prognostic information. While published guidelines outline what constitutes a "normal" and "abnormal" (i.e., exaggerated) blood pressure response to exercise testing, the widespread use of exaggerated blood pressure responses as a clinical tool is limited due to sparse and inconsistent data. A review of the original sources from these guidelines reveals an overall lack of empirical evidence to support both the normal blood pressure responses and their upper limits. In this current opinion, we critically evaluate the current exercise blood pressure guidelines including (1) the normal blood pressure responses to graded exercise testing; (2) the upper limits of this normal response; (3) the blood pressure criteria for test termination; and (4) the thresholds for exaggerated blood pressure responses. We provide evidence that exercise blood pressure responses vary according to subject characteristics, and subsequently a re-evaluation of what constitutes normal and abnormal responses is necessary to strengthen the clinical utility of this assessment.

Noninvasive Stress Testing for Coronary Artery Disease

Stress testing remains the cornerstone for noninvasive assessment of patients with possible or known coronary artery disease (CAD). The most important application of stress testing is risk stratification. Most patients who present for evaluation of stable CAD are categorized as low risk by stress testing. These low-risk patients have favorable clinical outcomes and generally do not require coronary angiography. Standard exercise treadmill testing is the initial procedure of choice in patients with a normal or near-normal resting electrocardiogram who are capable of adequate exercise. Stress imaging is recommended for patients with prior revascularization, uninterpretable electrocardiograms, or inability to adequately exercise.

Noninvasive stress testing for coronary artery disease

Stress testing remains the cornerstone for noninvasive assessment of patients with possible or known coronary artery disease (CAD). The most important application of stress testing is risk stratification. Most patients who present for evaluation of stable CAD are categorized as low risk by stress testing. These low-risk patients have favorable clinical outcomes and generally do not require coronary angiography. Standard exercise treadmill testing is the initial procedure of choice in patients with a normal or near-normal resting electrocardiogram who are capable of adequate exercise. Stress imaging is recommended for patients with prior revascularization, uninterpretable electrocardiograms, or inability to adequately exercise.

Hypotensive response during dobutamine stress echocardiography in coronary patients: a common event of well-functioning left ventricle

BACKGROUND

Hypotensive response during dobutamine stress echocardiography (DSE) is a common complication, lacking the prognostic significance of hypotension during exercise treadmill test.

HYPOTHESIS

The present study aimed to assess the possible mechanisms of hypotensive response during DSE and to compare it with exercise treadmill test.

METHODS

In all, 91 patients with known coronary artery disease (CAD) underwent both DSE and exercise treadmill test. Dobutamine-induced hypotension was defined as a systolic blood pressure drop > or = 20 mmHg from baseline or from the previous level of infusion.

RESULTS

Twenty-one (23%) patients, 10 of whom also had bradycardia, developed hypotension during dobutamine infusion. Five (5.5%) patients were severely symptomatic and the infusion was stopped prematurely, while in the remaining 16 the addition of atropine allowed the continuation of the test. Patients prone to hypotension were predominantly female (p = 0.0004), had smaller (p = 0.01) and better functioning left ventricles (p = 0.0004), were unlikely to have rest wall motion abnormalities (p = 0.0008) or multivessel CAD (p = 0.02), and had less ischemia (wall motion score difference) (p = 0.03). Hypotension during exercise treadmill test was observed in only one (1%) patient with left main disease.

CONCLUSION

Hypotension during DSE is unrelated to the anatomical or functional extent of CAD and is frequent in the setting of a well-functioning left ventricle. We suppose that vigorous contraction of a small chamber during dobutamine infusion results in an excessive stimulation of cardiac mechanoreceptors that mediate reflex hypotension and bradycardia.

Hypertensive response with exercise does not increase the prevalence of abnormal Tc-99m SPECT stress perfusion images

BACKGROUND

Systemic hypertension and an exaggerated blood pressure (BP) response with exercise have been associated with 'false-positive' findings on stress electrocardiography and echocardiography; however, limited data is available for stress myocardial perfusion imaging (MPI). The purpose of this study was to investigate whether an exaggerated elevation in BP with exercise is associated with an increased prevalence of abnormal MPI.

METHODS

BP responses to exercise were assessed in a cohort of 7,205 patients who underwent stress testing with technetium 99m-SPECT MPI (7/1999-6/2005) for the evaluation of chest pain or dyspnea.

RESULTS

A hypertensive response, defined as a peak systolic BP > or = 220 mmHg, occurred in 355 (4.9%) and was not associated with higher rates of ischemic ECG changes (16.1 versus 16.6%; P = .7), differences in Duke treadmill scores (4.7 +/- 4 versus 5.1 +/- 5; P = .3) or an increased prevalence of abnormal perfusion images (30.1% versus 32.9%; P = .3) to those without a hypertensive exercise response. Patients with a hypertensive response and either intermediate or high-risk MPI (on the basis of summed-difference-scores) referred for coronary angiography, had a high prevalence of coronary artery disease which was similar to those without a hypertensive response (88% versus 83%; P = .5). In an analysis of a community-based patient subset, a hypertensive response was not associated with a difference in either all-cause mortality or subsequent myocardial infarction, coronary revascularization or cardiac death (8% versus 9%; P = .7).

CONCLUSION

A hypertensive BP response to exercise is not associated with increased rates of ischemic ECG changes, higher-risk Duke treadmill scores, greater degrees of abnormal MPI or worse clinical outcome.

Significance of hypotensive response during dobutamine stress echocardiography

BACKGROUND

In patients undergoing exercise testing a hypotensive response is associated with a poor prognosis. There is limited information regarding the prognostic significance of hypotension during dobutamine stress test. This study investigates the association between a severe hypotensive response during DSE and long-term prognosis.

METHODS

Patients (3381) underwent dobutamine stress echocardiography (DSE). Blood pressure was measured automatically at rest and at the end of every dose-step. Wall motion was scored using a 16-segement, 5-point score. Ischemia was defined by the presence of new wall motion abnormalities. Hypotensive response during DSE was defined as mild (MHR) when systolic blood pressure (SBP) dropped <20 mmHg between rest and peak stress, and severe (SHR) when SBP dropped <20 mmHg. During follow-up all cause mortality and MACE (cardiac death or non-fatal myocardial infarction) were noted.

RESULTS

MHR and SHR occurred in 936 (28%) and 521 (15%) patients, respectively. Independent predictors of SHR were older age, new or worsening wall motion abnormalities and history of hypertension. During follow-up of 4.5 (+/-3.3) years, 920 patients died, of which 555 due to cardiac causes, and 713 patients experienced a MACE. After adjustment for baseline characteristics and DSE results SHR during DSE was independently associated with increased long-term cardiac death (HR: 1.3, 95% CI: 1.03-1.6) and MACE (HR: 1.34, 95% CI: 1.1-1.6), while MHR was not associated with a worse outcome.

CONCLUSIONS

Severe hypotensive response during DSE independently predicts cardiac death and MACE in patients with known or suspected coronary artery disease.

Two-phase reconstruction for the assessment of left ventricular volume and function using retrospective ECG-gated MDCT: comparison with echocardiography

OBJECTIVE

The aims of our study were to investigate the clinical feasibility of a two-phase reconstruction method based on ECG to evaluate left ventricular (LV) volume and function using cardiac MDCT and to compare these results with those from echocardiography.

SUBJECTS AND METHODS

The LV end-diastolic and end-systolic volumes, stroke volume, and ejection fraction were measured using two different methods of cardiac MDCT in 19 patients who had undergone cardiac MDCT and echocardiography. The first was a two-phase reconstruction method based on retrospective ECG-triggering: The end-systolic phase was reconstructed when the reconstruction window was located halfway in the ascending T wave on ECG, and the end-diastolic phase was reconstructed when the reconstruction window was located at the starting point of the QRS complex on ECG. The second was a multiphase reconstruction method: 20 series of images were reconstructed at every 5% throughout the cardiac cycle. The LV volumes and function determined by the two reconstruction methods were compared. The results measured by cardiac MDCT were compared with those obtained by echocardiography.

RESULTS

The LV end-diastolic and end-systolic volumes, stroke volume, and ejection fraction measured by the two-phase reconstruction method correlated well with those measured by the multiphase reconstruction method (r = 0.984, 0.978, 0.969, 0.969, respectively). There were no significant differences between the results of the two different reconstruction methods (p > 0.05). The LV volumes showed moderate to good correlation between cardiac MDCT and echocardiography (0.766 < r < 0.940). Ejection fraction measured by cardiac MDCT yielded a significant overestimation of 2.9% +/- 8.7% (mean +/- SD) compared with that measured by echocardiography.

CONCLUSION

A two-phase reconstruction method on cardiac MDCT is relatively simple and can provide an objective standard for reconstructing the appropriate image sets for end-diastole and end-systole without the need to review serial preview images.

Prediction of long-term prognosis in 12 169 men referred for cardiac rehabilitation

BACKGROUND

Predicting the risk of cardiac and all-cause death in patients with established coronary heart disease is important in counseling the individual and designing risk-stratified rehabilitation and secondary prevention programs. Cox proportional hazards and Kaplan-Meier survival curves were thus completed on initial assessment data obtained from patients referred to an outpatient cardiac rehabilitation center.

METHODS AND RESULTS

A single-center prospective observational design took peak cardiorespiratory exercise test data for 12 169 male rehabilitation candidates aged 55.0+/-9.6 years (7096 myocardial infarctions [MIs], 3077 coronary artery bypass grafts [CABGs], and 1996 documented cases of ischemic heart disease [IHD]). A follow-up of 4 to 29 years (median, 7.9) yielded 107 698 man-years of experience. Entry data were tested for associations with time to cardiac and all-cause death. We recorded 1336 cardiac deaths (953 MI, 225 CABG, and 158 IHD) and 2352 all-cause deaths. A powerful predictor of cardiac and all-cause mortality was measured peak oxygen intake (VO2peak). For the overall sample, values of <15, 15 to 22, and >22 mL/kg per minute yielded respective multivariate adjusted hazard ratios of 1.00, 0.62, and 0.39 for cardiac and 1.00, 0.66, and 0.45 for all-cause deaths. For the separate diagnostic categories, apart from VO2peak, the only other significant predictors of cardiac death common to all 3 were smoking and digoxin, and for all-cause death, age, smoking, digoxin, and diabetes.

CONCLUSIONS

Exercise capacity, as determined by direct measurement of VO2peak, exerts a major long-term influence on prognosis in men after MI, CABG, or IHD and can play a valuable role in risk stratification and counseling.

Principal uses of myocardial perfusion scintigraphy in the management of patients with known or suspected coronary artery disease

The use of myocardial perfusion single photon emission computed tomography (SPECT) has undergone considerable expansion and evolution over the past 2 decades. Although myocardial perfusion imaging was first conceived as a noninvasive diagnostic tool for determining the presence or absence of coronary artery disease, its prognostic value is now well established. Thus, identification of patients at risk for future cardiac events has become a primary objective in the noninvasive evaluation of patients with chest pain syndromes and among patients with known coronary artery disease. In particular, the ability of myocardial perfusion SPECT to identify patients at low (< 1%), intermediate (1% to 5%) or high (> 5%) risk for future cardiac events is essential to patient management decisions. Moreover, previous studies have conclusively shown the incremental prognostic value of myocardial perfusion SPECT over clinical and treadmill exercise data in predicting future cardiac events. This report addresses the current role and new developments, with respect to the use of myocardial perfusion imaging, in determining patient risk for cardiac events and the cost-effective integration of such information into patient management decisions.

Diagnostic usefulness of the post-exercise systolic blood pressure response for the detection of coronary artery disease in patients with diabetes mellitus

Patients with diabetes mellitus (DM) often have a positive result on exercise testing despite a normal coronary arteriogram, which indicates that exercise-induced ST depression is not always an accurate indicator of the presence of coronary artery disease (CAD) in such patients. The present study evaluated the usefulness of the post-exercise systolic blood pressure (SBP) response for the detection of CAD in 47 consecutive patients with DM. Significant stenotic lesions were detected by angiography in 25 patients; 18 of these had true positive (TP) exercise testing results, and 7 had false negative (FN) results. No significant stenotic lesions were detected in the remaining 22 patients and of these 10 had true negative (TN) exercise testing results, and 12 had false positive (FP) results. The SBP ratio (SBP after 3 min of recovery divided by the SBP at peak exercise) was significantly higher in patients with coronary stenoses than in those without. Analysis of the relative cumulative frequency revealed that a SBP ratio greater than 0.87 was associated with significant stenoses. The sensitivity, specificity, and accuracy of ST change combined with a SBP ratio greater than 0.87 for detecting stenoses in patients with DM were 68%, 82%, and 74%, respectively. These results suggest that calculating the SBP ratio, in combination with monitoring for ST depression, improves the accuracy of treadmill exercise testing for the detection of CAD in patients with DM.

Usefulness of hypotension during dobutamine echocardiography in predicting perioperative cardiac events

This study was undertaken to determine the prognostic significance of hypotension induced during preoperative dobutamine stress echocardiography (DSE) before vascular and noncardiac thoracic surgery. Wall motion abnormality during DSE predicts perioperative risk. Although hypotension during DSE has not been shown to correlate with the presence or severity of coronary artery disease, its significance in perioperative risk assessment is unknown. We retrospectively studied 300 patients who had DSE within 6 months of noncardiac surgery. Perioperative events including death, myocardial infarction, ischemia, and arrhythmias were recorded. Odds ratios with 95% confidence intervals were used to examine the association between clinical and echocardiographic variables and perioperative events. A hypotensive response during DSE was seen in 85 patients (28%). Forty-eight patients (16%) had 54 perioperative complications including 4 cardiac-related deaths, 10 myocardial infarctions, 12 myocardial ischemic events, and 28 arrhythmias. Hypotension during DSE was predictive of the combined end point of perioperative cardiac mortality, myocardial infarction, and ischemia (odds ratio 4.04, 95% confidence interval 1.72 to 9.51). In a multivariate logistic regression model, hypotension during DSE remained a significant predictor (odds ratio 4.10, p<0.01). DSE-related hypotension was predictive of perioperative cardiac events and therefore may have a role in risk stratification before vascular or noncardiac thoracic surgery.

Prognostic value of systemic blood pressure response during exercise in a community-based patient population with hypertrophic cardiomyopathy

OBJECTIVES

The present study was designed to prospectively evaluate the prognostic relevance of abnormal blood pressure response to exercise (ABPR), defined as hypotension or failed blood pressure increase (<20 mm Hg) with exercise, in a community-based hypertrophic cardiomyopathy (HCM) population representative of the overall disease spectrum.

BACKGROUND

Abnormal blood pressure response to exercise has been proposed as a marker for hemodynamic instability and increased risk for disease-related mortality in highly selected patient populations with HCM.

METHODS

The study population comprised 126 patients (aged 42+/-14 years) who underwent maximal symptom-limited cycloergometer exercise testing as part of the standard evaluation at our institution, and who were followed systematically for 4.7+/-3.7 years after testing.

RESULTS

Of the 126 study patients, 98 (78%) had a normal blood pressure response during exercise, whereas the other 28 (22%) had ABPR, including nine with hypotension and 19 with failed blood pressure rise. During the follow-up period, nine patients (7%) died of HCM-related causes (three suddenly and six heart failure-related), of whom four had ABPR. In those patients aged < or =50 years, survival analysis after exercise testing showed a significantly increased risk for cardiovascular mortality associated with ABPR compared with a normal exercise response (p = 0.04), with an odds ratio of 4.5 (95% confidence interval: 1.1, 20.1). However, ABPR showed low positive predictive accuracy for cardiovascular mortality (i.e., 14%), whereas negative predictive accuracy was high (i.e., 95%).

CONCLUSIONS

A hypotensive blood pressure response during exercise occurred in over 20% of a community-based patient cohort with HCM, and was associated with adverse long-term prognosis in patients <50 years old. However, the positive predictive accuracy of this blood pressure response is too low to justify modifications of clinical management or to allow identification of the high-risk patient based solely on an abnormal test result. By virtue of its high negative predictive accuracy for HCM-related mortality, the blood pressure response to exercise appears to be most valuable (in conjunction with the absence of other well recognized risk factors) as a screening test for the identification of low-risk subsets of patients.

Prognostic value of myocardial perfusion imaging in patients with high exercise tolerance

BACKGROUND

Although high exercise tolerance is associated with an excellent prognosis, the significance of abnormal myocardial perfusion imaging (MPI) in patients with high exercise tolerance has not been established. This study retrospectively compares the utility of MPI and exercise ECG (EECG) in these patients.

METHODS AND RESULTS

Of 388 consecutive patients who underwent exercise MPI and reached at least Bruce stage IV, 157 (40.5%) had abnormal results and 231 (59.5%) had normal results. Follow-up was performed at 18+/-2.7 months. Adverse events, including revascularization, myocardial infarction, and cardiac death, occurred in 40 patients. Nineteen patients had revascularization related to the MPI results or the patient's condition at the time of MPI and were not included in further analysis. Seventeen patients (12.2%) with abnormal MPI and 4 (1.7%) with normal MPI had adverse cardiac events (P<0.001). Cox proportional-hazards regression analysis showed that MPI was an excellent predictor of cardiac events (global chi2=13.2; P<0.001; relative risk=8; 95% CI=3 to 23) but EECG had no predictive power (global chi2=0.05; P=0.8; relative risk=1; 95% CI=0.4 to 3.0). The addition of Duke's treadmill score risk categories did not improve the predictive power of EECG (global chi2=0.17). The predictive power of the combination of EECG (including Duke score categories) and MPI was no better than that of MPI alone (global chi2=13.5).

CONCLUSIONS

Unlike EECG, MPI is an excellent prognostic indicator for adverse cardiac events in patients with known or suspected CAD and high exercise tolerance.

Forearm vascular responses during semierect dynamic leg exercise in patients following myocardial infarction

We assessed forearm vascular and blood pressure responses to dynamic leg exercise in patients 7 and 28 days postmyocardial infarction. To determine a possible association between abnormal exercise vascular responses and baroreflex dysfunction, integrated and carotid baroreflex sensitivity and forearm vascular responses (during application of subhypotensive lower body negative pressure) were assessed. On day 7, 42 patients were compared with 21 age- and sex-matched controls. All subjects were assessed for (1) forearm vascular resistance during semierect exercise, (2) blood pressure measurements during erect treadmill exercise, and (3) integrated, cardiopulmonary, and carotid baroreceptor sensitivity. These studies were repeated in 13 patients on day 28. Forearm vascular resistance increased during exercise by 36% +/- 63% in patients versus 121% +/- 105% in controls (P = 0.0001), and fell in 15 patients, a response seen in none of the controls. Exercise hypotension was demonstrated in 5 patients, all of whom had abnormal vasodilator vascular responses. Those patients with vasodilator responses had a lower left ventricular ejection fraction (52% +/- 12% vs 62% +/- 9%; P = 0.007), and lower cardiopulmonary mechanoreceptor sensitivity (-6.6 +/- 3.9 units vs +6.4 +/- 10.4 units, P = 0.02) than those with constrictor responses, respectively. In the 13 patients studied on day 28, the change in forearm vascular resistance was similar to that observed on day 7 (36% +/- 63% vs 46% +/- 73%). Paradoxical vasodilation of forearm vessels during leg exercise is common in patients studied 7 and 28 days postmyocardial infarction, and is associated with lower left ventricular ejection fraction and abnormal vascular responses during subhypotensive lower body negative pressure.

Effect of gender and left ventricular dysfunction on the incidence of hypotension induced by dobutamine stress echocardiography

BACKGROUND

Of patients who undergo dobutamine stress echocardiography (DSE), 14% to 38% experience hypotension that sometimes requires termination of the test before an adequate cardiac work-load is reached. The mechanisms of hypotension reportedly are related to peripheral vasodilation, a decrease in cardiac output, and left ventricular (LV) cavity obliteration. DSE is performed increasingly in women and in patients with LV dysfunction. However, the impact of gender and LV dysfunction on DSE-induced hypotension has not been elucidated.

METHODS AND RESULTS

Clinical, hemodynamic, and echocardiographic characteristics were studied in 412 patients undergoing DSE, 82 patients with an LV ejection fraction of 40% or less, and 147 women. Hypotension, defined as a decrease in systolic blood pressure of at least 20 mm Hg, occurred in 117 (28%) patients. Hypotension was more common in women than men (36% vs 24%, P = .01). Hypotension was also more common in older adults (P = .004), persons taking diuretics (P = .025) or angiotensin-converting enzyme inhibitors (P = .01), and persons with higher baseline blood pressures (P < .0001). Hypotension was not related to the use of beta blockers, calcium channel blockers, digoxin, nitrates, LV dimensions, or ejection fraction.

CONCLUSIONS

The incidence of DSE-induced hypotension is related to gender but not to the level of LV systolic function. It also is associated significantly with higher age, and use of angiotensin-converting enzyme inhibitors or diuretics.

Impaired systolic blood pressure response to dobutamine stress testing: a marker of more severe functional abnormalities in patients with myocardial infarction

Dobutamine-induced hypotension has been disregarded as a marker of more severe functional abnormalities in patients with suspected coronary artery disease. However, its functional significance in patients with myocardial infarction has not been studied. The aim of this study was to define the predictors of systolic blood pressure (SBP) response to dobutamine in patients with previous myocardial infarction. Dobutamine stress (up to 40 microg/kg per minute) echocardiography was performed in 326 patients with prior myocardial infarction referred for evaluation of myocardial ischemia. A 16-segment, four-grade score model was used to assess left ventricular function. Wall motion score index was derived by summation of wall motion score divided by 16. SBP and heart rate increased from rest to peak dobutamine stress (127 +/- 22 vs 134 +/- 27 mm Hg and 72 +/- 14 vs 122 +/- 24 bpm, p < 0.00001 in both). An increase of SBP > or = 30 mm Hg occurred in 50 patients (15%). By multivariate analysis, independent predictors of failure of SBP increase were higher peak wall motion score index (p < 0.001), higher resting SBP (p < 0.01), and medication with calcium channel blockers (p < 0.05). SBP drop > or = 20 mm Hg occurred in 54 patients (17%). Independent predictors of SBP drop were higher resting wall motion score index (p < 0.001), higher resting SBP (p < 0.0001), and older age (p < 0.05). In patients with myocardial infarction, left ventricular function and baseline systolic blood pressure are powerful predictors of SBP response to dobutamine stress testing.

Delayed recovery of postexercise blood pressure in patients with chronic heart failure

Thirty-four patients with idiopathic dilated and ischemic cardiomyopathy underwent a symptom-limited cardiopulmonary exercise testing to evaluate the significance of postexercise blood pressure (BP) response. The postexercise BP response was useful in assessing the impaired exercise capacity and increased sympathetic activity in patients with heart failure.

Prognostic significance of systolic blood pressure changes during dobutamine-atropine stress technetium-99m sestamibi perfusion scintigraphy in patients with chest pain and known or suspected coronary artery disease

To investigate the prognostic value of dobutamine stress-induced changes in systolic blood pressure (BP) 418 patients (mean age 60 years, 238 men) with chest pain and known or suspected coronary artery disease, who underwent a dobutamine-atropine stress technetium-99m sestamibi myocardial perfusion scintigraphic study, were followed up for 25 +/- 15 months. Blood pressure was measured by automatic sphygmomanometry every 3 minutes. A marked decrease and increase in systolic BP from rest to peak were defined as changes of > or = 20 mm Hg, and > or = 30 mm Hg, respectively. Worst outcome events were cardiac death (n = 30), nonfatal myocardial infarction (n = 17), and hospitalization for congestive heart failure (n = 8). A decrease in systolic BP (prevalence 16%) was associated with older age and higher baseline systolic BP. Fixed and reversible sestamibi perfusion defects and follow-up results were similar to patients without a systolic BP decrease. In contrast, an increase in systolic BP (prevalence 24%) was associated with younger age, lower baseline systolic BP, and with absence of a history of prior congestive heart failure or treatment with angiotensin-converting enzyme inhibitors. Furthermore, these patients had fewer fixed perfusion defects and tended to have fewer annual event rates (3.5% vs 7.5%, p < 0.10). In a multivariate model, an increase in systolic BP was not an independent predictor for subsequent events. In conclusion, a dobutamine-induced decrease in systolic BP is not associated with fixed or reversible sestamibi defects or adverse prognosis. An increase in systolic BP, however, is associated with less fixed sestamibi defects and a tendency toward less annual event rates.

Maximal exercise hemodynamics and risk of mortality in apparently healthy men and women

The purpose of this investigation was to determine the association of maximal exercise hemodynamic responses with risk of mortality due to all-causes, cardiovascular disease (CVD), and coronary heart disease (CHD) in a population of apparently healthy individuals. Study participants were 20,387 men (mean age = 42.2 yr) and 6,234 women (mean age = 41.9 yr), patients of a preventive medicine center in Dallas, TX, examined between 1971 and 1989. Maximal heart rate and maximal systolic blood pressure (SBP) measured during the maximal exercise test were related to risk of all-cause, CVD, and CHD mortality. During an average of 8.1 yr of follow-up, there were 348 deaths in men and 66 deaths in women. Among men, after adjustment for confounding variables, risks (and 95 percent confidence interval (CI)) of all-cause mortality for quartiles of maximal SBP, relative to the lowest quartile, were: 0.96 (0.70-1.33), 1.36 (1.01-1.85), and 1.37 (0.98-1.92) for quartiles 2-4, respectively. Similarly adjusted risks for maximal heart rate were: 0.61(0.44-0.85), 0.69 (0.51-0.93), and 0.60 (0.41-0.87). Similar results were seen for risk of CVD and CHD death. In women, similar trends in adjusted risks of all-cause and CVD mortality across maximal SBP and heart rate categories were observed. For maximal heart rate, a 35 bpm higher value was associated with a 36 percent decreased risk of CVD mortality in men (RR = 0.63,95 percent CI = 0.34-0.71) and an 8 percent lower risk in women (RR = 0.92,95 percent CI = 0.18-4.63). These results suggest that an exaggerated SBP or an attenuated heart rate response to maximal exercise may indicate an elevated risk for mortality in this apparently healthy population.

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.

Left ventricular outflow tract obstruction as a cause for hypotension and symptoms during dobutamine stress echocardiography

BACKGROUND

Hypotension has been found to occur in more than one-third of patients during DBSE. Unlike traditional treadmill exercise stress testing, hypotension does not appear to be associated with significant coronary artery disease or left ventricular (LV) dysfunction. Several ischemic and nonischemic mechanisms such as dynamic LV intracavitary obstruction have been implicated in the pathogenesis of hypotension and the induction of symptoms during DBSE.

HYPOTHESIS

The purpose of this study was the prospective evaluation of patients referred for dobutamine stress echocardiography (DBSE) to determine (1) the frequency of hypotension during DBSE, (2) the underlying mechanisms responsible for the induction of hypotension, and (3) to describe the cardiac chamber sizes and mass of patients in whom hypotension occurs.

METHODS

Seventy-eight consecutive patients were studied during DBSE. Pulsed and continuous-wave Doppler echocardiography were performed at baseline and at each dobutamine infusion stage. Maximum velocities were recorded. Cardiac output was determined noninvasively at each stage in patients who developed an outflow tract gradient. Echocardiography was used to characterize LV dimensions and mass.

RESULTS

During dobutamine infusion, 14 of 78 (18%) patients developed a left ventricular outflow tract (LVOT) velocity > or = 2.5 m/s. Pulsed Doppler echocardiography verified that the maximal velocity originated in the LVOT. Of the patients who developed an LVOT gradient, 57% had a concomitant hypotensive response to dobutamine compared with 33% of patients without a gradient (not significant). Four of nine patients had a simultaneous fall in cardiac output. Patients who developed an LVOT gradient had smaller LV dimensions and increased wall thicknesses compared with those who did not develop a gradient.

CONCLUSIONS

Dobutamine stress echocardiography precipitates LVOT obstruction in certain patients. The development of a gradient corresponded with a fall in blood pressure and a decline in cardiac output in nearly half of the patients. These findings suggest that stress-induced LVOT obstruction may be responsible in part for the hemodynamic changes and symptoms experienced by these patients during exercise.

[Cardiovascular evaluation in athletic children]

Although rare, sports related sudden cardiac deaths in children and adolescents justify the search for risk factors in any child or adolescent who wishes to practice sports. Each time that history and careful clinical cardiovascular examination point to a possible cardiovascular abnormality, an electrocardiogram and an echocardiography must be performed. Exercise testing is useful to appreciate the cardiovascular tolerance, either in normal subjects or in subjects with a cardiovascular abnormality; its interpretation requires good knowledge and understanding of hemodynamic responses to exercise. Indications, risks and procedures of exercise testing are discussed with reference to exercise physiology.

Hypotension during dobutamine stress echocardiography: is it related to dynamic intraventricular obstruction?

Although it has been shown that a hypotensive response during dobutamine stress echocardiography is not a marker of coronary artery disease, the mechanism of this response remains unclear. We hypothesize that hypotension during dobutamine stress echocardiography is not related to the development of dynamic intraventricular obstruction. The development of left ventricular outflow obstruction was defined as a late-peaking Doppler velocity profile that exceeded baseline outflow velocity by at least 1 m/sec in 104 consecutive patients undergoing dobutamine stress echocardiography. Left ventricular outflow obstruction was seen in 13% of 15 patients with a hypotensive response (group 1) and in 13% of 89 patients without a hypotensive response (group 2). The mean baseline systolic blood pressure was 157 +/- 21 mm Hg in group 1 compared to 139 +/- 25 mm Hg in group 2 (p = 0.008). An ischemic response to dobutamine infusion as manifested by the development of new or worsening wall motion abnormalities was seen in 40% of group 1 patients and 34% of group 2 patients (p = 0.77). These data demonstrate that a hypotensive response is not related to the development of dynamic intraventricular obstruction during dobutamine stress echocardiography. Rather, there is a significant association between a higher baseline systolic blood pressure and a hypotensive response during dobutamine infusion.

Does hypotension during dobutamine stress echocardiography correlate with anatomic or functional cardiac impairment?

The development of hypotension during various exercise stress tests has been correlated with the presence of multivessel coronary artery disease and impaired left ventricular contractility. Hypotension may also occur during dobutamine stress echocardiography; however, its anatomic and functional significance remains unknown. As part of an ongoing study of restenosis, dobutamine stress echocardiography and diagnostic cardiac catheterization were performed on the same day in 105 outpatients approximately 6 months after percutaneous coronary revascularization (balloon angioplasty or directional coronary atherectomy) to determine the anatomic and functional significance of dobutamine-induced hypotension. Dobutamine was infused in stepwise increments to a maximum rate of 30 micrograms/kg/min. Hypotension was defined as a reduction in systolic blood pressure of > or = 15 mm Hg. Anatomic abnormalities were defined by quantitative coronary angiography and functional abnormalities by digitized two-dimensional stress echocardiography. Clinical, angiographic, hemodynamic, and electrocardiographic data underwent multivariable regression analysis to determine their ability to predict independently the development of dobutamine-induced hypotension. Dobutamine-induced hypotension was not associated with the presence of severity of coronary artery disease or with echocardiographic wall motion abnormalities. Univariable predictors of stress-induced hypotension included high baseline systolic blood pressure, advanced age, and high left ventricular ejection fraction. Only a high baseline systolic blood pressure contributed independent predictive information in multivariable stepwise logistic regression analysis. Therefore, the development of hypotension during dobutamine stress echocardiography, unlike that during traditional exercise stress tests, is not associated with the presence of significant coronary artery disease or left ventricular dysfunction.

Mechanism of exercise hypotension in patients with ischemic heart disease. Role of neurocardiogenically mediated vasodilation

BACKGROUND

Exercise-induced hypotension in patients with coronary artery disease (CAD) has been considered to be due to an inability to achieve an adequate increase in cardiac output to match the demands of exercise. We investigated 10 consecutive patients (9 men and 1 woman; age, 38 to 71 years; mean, 52 years) with angiographically documented CAD and exercise-induced hypotension (EIH) (BPPeak < BPRest). Ten approximately age- and sex-matched patients with documented CAD and normal exercise blood pressure response (NBP) served as control subjects.

METHODS AND RESULTS

Nine patients with EIH and all 10 control subjects underwent forearm plethysmography and radionuclide ventriculography (RNV) during semierect cycle exercise. Forearm vascular resistance (FVR) fell by 35 +/- 21% in exercise-induced hypotension patients versus an increase of 78 +/- 65% in patients with an NBP response (P < .0001). Left ventricular ejection fraction increased by 5.1 +/- 7.5% in the group with EIH versus a fall of 4.1 +/- 6.2% in the control group (P = .004). Cardiac output at peak exercise (RNV) increased by 2.2 +/- 0.89-fold in the group with EIH versus 1.49 +/- 0.47-fold in the control group (P = .04). The tenth patient in the group with EIH underwent invasive hemodynamic evaluation during erect exercise. Systolic blood pressure fell (136/80Rest to 50/40Peak) and cardiac output (Fick) tripled, whereas calculated systemic vascular resistance decreased by a factor of 10. Successful angioplasty to an isolated circumflex lesion resulted in resolution of symptoms and abnormal hemodynamic responses during exercise.

CONCLUSIONS

Abnormal vasodilation associated with a normal or even increased rather than decreased cardiac output response appears to be an important mechanism underlying EIH in some patients with CAD. In the present study, this appears to have been the dominant mechanism in 8 and contributory in 2 of the consecutive patients studied.

Influence of right coronary artery stenosis on exercise test responses and survival in patients with left main or left main equivalent disease

Forty-two patients with angiographically documented left main coronary artery (LM) disease (luminal occlusion > or = 50%) and 30 patients with left main equivalent (LMEQ) disease (> or = 70% luminal occlusion of both the proximal left anterior descending artery and proximal left circumflex artery) were studied to determine the role of right coronary artery (RCA) involvement on exercise test responses and survival. Significant (> or = 70%) RCA stenosis was present in 30 (72%) of the 42 LM patients and 16 (53%) of the 30 LMEQ patients. No significant differences were observed between LM and LMEQ patients in any clinical or exercise variables or survival. Thus both groups were combined for analysis of the influence of RCA involvement (i.e., LM/LMEQ with RCA versus LM/LMEQ without RCA disease). Greater ischemic responses were observed in the LM/LMEQ group with significant stenosis of the RCA. The presence of RCA stenosis was associated with significantly greater horizontal or downsloping ST-segment depression during exercise (2.4 +/- 1.2 mm vs 1.3 +/- 1.4 mm; p < 0.001), and prolonged recovery time until normalization of the ST segment (3.2 +/- 1.4 min vs 2.0 +/- 1.9 min; p < 0.01). The LM/LMEQ without RCA disease group behaved like the subgroup with two-vessel disease, and responses of the LM/LMEQ group with RCA disease were similar to the group with three-vessel disease. The annual survival in LM/LMEQ with RCA disease was worse than that in LM/LMEQ without RCA disease (average annual mortality rates = 7.5% vs 1.0%, respectively; p = 0.05). Infarct-free survival in LM/LMEQ with RCA disease was also lower than that in LM/LMEQ without RCA disease. Thus although patients with LM and LMEQ were similar in terms of survival and exercise responses, the presence of RCA stenosis was associated with significantly greater ST-segment depression, a prolonged recovery time until normalization of the ST segment, a fivefold increase in the death rate, and higher morbidity from myocardial infarction over a 5-year period of follow-up. Involvement of the RCA should be considered when making decisions concerning medical-surgical management of patients with severe coronary artery disease.

Abnormal systolic blood pressure response during exercise recovery in patients with angina pectoris

OBJECTIVES

This study was conducted to clarify the mechanisms of the abnormal systolic blood pressure response after exercise in patients with angina pectoris.

BACKGROUND

An abnormal systolic blood pressure response in patients with angina pectoris has been observed not only during exercise but also during the recovery period after exercise. However, the mechanisms of this abnormal response during recovery have not been elucidated.

METHODS

Thirty-five patients with angina pectoris and 17 control subjects underwent bicycle ergometric studies after insertion of a Swan-Ganz catheter.

RESULTS

In control subjects, all hemodynamic variables decreased rapidly after exercise. In 7 of the 35 patients, systolic blood pressure increased after exercise. The patients with angina were classified into two groups. In group I (17 patients), changes in systolic blood pressure during recovery were smaller than those in control subjects. In group II (18 patients) recovery of systolic blood pressure was normal. Changes in stroke index from rest to peak exercise were smaller in group I than in group II. Stroke index in both patient groups increased paradoxically during recovery. The increase in systemic vascular resistance index during recovery and the ratio of plasma norepinephrine concentration to cumulative work load were greater in group I than in group II.

CONCLUSIONS

An abnormal systolic blood pressure response after physical exercise in patients with angina pectoris is indicative of severe myocardial ischemia during exercise and may be caused by an increase in stroke volume due to recovery from myocardial ischemia and increased systemic vascular resistance secondary to exaggerated sympathetic nervous activity.

Paradoxic hypotension during dobutamine stress echocardiography: clinical and diagnostic implications

OBJECTIVES

The purpose of this study was to elucidate the prevalence, magnitude and clinical implications of a hypotensive response during dobutamine stress echocardiography.

BACKGROUND

Dobutamine stress echocardiography is an accurate noninvasive method for detecting coronary artery disease. It has been associated with unexpected hypotension in a proportion of patients. Hypotension occurring during exercise testing has been associated with an increased prevalence of multivessel coronary artery disease and a poor prognosis. The clinical significance of hypotension when seen during dobutamine infusion for diagnostic testing is unknown.

METHODS

Clinical characteristics, coronary artery anatomy (n = 41), ventricular function at rest and during dobutamine infusion and prognosis were evaluated in 115 patients experiencing hypotension during dobutamine stress echocardiography and compared with data in 59 nonhypotensive catheterized patients for comparison of coronary anatomy and in 239 nonhypotensive patients for prognostic purposes.

RESULTS

Hypotension occurred in 115 (20%) of 568 consecutive patients studied with dobutamine stress echocardiography. It was gradual in 73 and precipitous in 42 patients. There were no statistical differences among the hypotensive groups and the index group in prevalence or severity of coronary disease or in prognosis during 15 months compared with findings in nonhypotensive patients.

CONCLUSIONS

Hypotension occurs commonly during dobutamine stress echocardiography, and patients with dobutamine-induced hypotension constitute a heterogeneous group. Unlike hypotension occurring with exercise testing, dopamine-induced hypotension is not invariably associated with advanced coronary disease or an adverse prognosis.

Mechanism of exercise-induced hypotension in coronary artery disease

Hypotension during exercise testing has been considered a marker of extensive coronary artery disease (CAD) and poor prognosis. The mechanism of hypotension was examined in 25 CAD patients who developed hypotension during treadmill exercise testing (mean decrease in systolic blood pressure [BP] 33 +/- 13 mm Hg) (group 1) and was compared with the results of 25 CAD patients who had a normal systolic BP response to exercise (mean increase 53 +/- 15 mm Hg) (group 2). The 2 groups were comparable in age, sex, extent of CAD, previous myocardial infarction, left ventricular ejection fraction, history of hypertension and cardiac medications. Exercise heart rate (121 +/- 23 vs 133 +/- 25 beats/min; p = not significant [NS]) and duration (6 +/- 2 vs 7 +/- 3 minutes; p = NS) were comparable. ST-segment depression occurred in 44% of patients in group 1 and in 52% in group 2 (p = NS), and angina during exercise occurred in 60% of both groups. Single-photon emission computed tomographic thallium images were abnormal in 24 patients (96%) in group 1 and in 20 patients (80%) in group 2 (p = NS). Percent thallium abnormality was 19 +/- 12% in group 1, and 18 +/- 14% in group 2 (p = NS), and the severity of thallium abnormality was 710 +/- 510 in group 1, and 510 +/- 500 in group 2 (p = NS). Ischemia involving the inferior/posterior segments was seen in 68% of patients in group 1 and in 60% in group 2 (p = NS). Increased lung thallium uptake was seen in 48% of both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypotension during dobutamine stress echocardiography: initial description and clinical relevance

Hypotension during exercise treadmill testing is correlated with the presence of coronary artery disease, its severity, and prognosis. The importance of hypotension during dobutamine stress testing has not been previously reported to our knowledge. We reviewed 43 cases of hypotension occurring in 42 patients out of a total of 116 consecutive stress dobutamine echocardiographic procedures performed in a total of 112 patients. Of the 42 patients with hypotension, 20 underwent cardiac catheterization. Regional wall motion abnormalities induced by dobutamine infusion were found in 13 of these patients, all of whom had significant (greater than or equal to 70% diameter reduction) coronary artery disease. The remaining seven patients without regional wall motion abnormalities did not have significant coronary artery disease at catheterization. Of the remaining 22 patients with dobutamine-induced hypotension, 20 had no induced regional wall motion abnormalities, were not catheterized, and were followed clinically. None of these patients had a cardiac event during a mean follow-up period of 11.5 months. We conclude that hypotension during dobutamine stress echocardiography in the absence of regional wall motion abnormalities does not indicate significant coronary artery disease or portend an adverse prognosis.

Exercise testing and left main coronary artery stenosis. Can patients with left main disease be identified?

Exercise testing is commonly used to evaluate patients with coronary artery disease who have serious anatomic characteristics. To study the characteristic exercise test variables in patients with left main coronary artery disease, the computerized data base of the Hungarian Institute of Cardiology Exercise Test Laboratory was used. Among 2,378 patients who had undergone a supine bicycle exercise test and who had abnormal coronary angiographic results, 65 patients with significant (greater than 50 percent diameter narrowing) stenosis of the left main coronary artery were found. The 65 patients were subgrouped according to their previous history and other vessel involvement. Nine patients had isolated left main coronary artery disease and no myocardial infarction (group 1); 28 patients had left main coronary artery stenosis and another diseased vessel but no prior myocardial infarction (MI) (group 2); and 28 patients had left main coronary artery disease, another diseased vessel, and a prior MI (group 3). For comparison, the 27 patients selected to be the control group (group C) had no history of MI but had significant stenosis of both the left anterior descending and the left circumflex arteries. Exercise time, calculated oxygen consumption, maximal work load, time to ST depression, prevalence of ST segment depression, and maximal ST depression were similar in the groups. Maximal heart rate and double product were higher in group 1, but we could find no single variable or group of variables characteristic of left main coronary artery disease.

Abnormal blood pressure response during exercise in hypertrophic cardiomyopathy

To investigate the incidence of abnormal exercise blood pressure responses in hypertrophic cardiomyopathy (HCM) and the potential role of hemodynamic instability as a mechanism of sudden death, 129 consecutive patients with HCM underwent maximal symptom-limited treadmill exercise testing with blood pressure recording. Four patterns of blood pressure response were observed. Forty-three patients had significant exercise hypotension, with either a continuous fall in systolic blood pressure (n = 5) from the start of exercise or a sudden fall in systolic blood pressure (20-100 mm Hg; mean, 40 mm Hg) from the peak value (n = 38), 23 patients had a normal response during exercise but an abnormal blood pressure response in the recovery period, and the remaining 62 patients demonstrated a normal blood pressure response. Patients with exercise hypotension were younger (33 +/- 14 versus 46 +/- 14 years) and more of them had a family history of HCM and sudden death compared with those with a normal blood pressure response (15 of 43 versus 6 of 62 patients). Similarly, the 23 patients with abnormal recovery blood pressure responses were younger (43 +/- 16 versus 46 +/- 14 years) and had a higher incidence of a family history of sudden death (10 of 24 versus 6 of 62 patients). Left ventricular cavity dimensions were smaller in those with exercise hypotension, but 11 other clinical, echocardiographic, and arrhythmic variables were similar. To assess the mechanism of exercise hypotension, 14 patients who demonstrated exercise hypotension and 14 symptomatic patients with a normal exercise blood pressure response underwent invasive hemodynamic exercise testing.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanism of abnormal postexercise systolic blood pressure response and its diagnostic value in patients with coronary artery disease

To define the factors that affect an abnormal postexercise systolic blood pressure (SBP) response and to verify the diagnostic value of that response in patients with coronary artery disease (CAD), we studied 33 normal subjects, eight patients with hypertension who had no CAD, and 42 patients with documented CAD who underwent supine leg exercise testing. SBP recovery ratios were derived by dividing the values obtained 1 and 3 minutes after exercise by the peak value. The upper normal limit of the SBP ratio was defined by two standard deviations from the mean for 33 normal subjects. The specificity of this criterion for identifying patients with CAD was 97% and the sensitivity was 60%. None of the eight patients with hypertension showed an abnormal postexercise SBP response. At peak exercise the pulmonary artery wedge pressure was significantly greater in the patients with CAD having an abnormal response. In multiple regression analysis the exercise pulmonary artery wedge pressure, the exercise SBP, and the systemic vascular resistance after exercise were determining factors for an abnormal SBP response. Three-vessel disease was more common in patients with an abnormal response. Results of this study indicate that an abnormal postexercise SBP response appears to be determined by (1) the extent of exercise-induced impairment of left ventricular function and (2) peripheral vascular tone during recovery. This study also suggests that this criterion can increase the specificity of supine exercise testing in patients with CAD including those with hypertension and might provide a marker for the severity of impaired left ventricular function by exercise in CAD.

Prognostic value of abnormal postexercise systolic blood pressure response: prehospital discharge test after myocardial infarction in Japan

To assess the prognostic value of an abnormal postexercise response in systolic blood pressure (SBP), treadmill exercise testing was performed in 217 survivors of acute myocardial infarction at an average of 9.3 weeks after infarction. During the mean follow-up period of 4 years, cardiac events were noted in 34 patients (16%), including cardiac death in 13 (6%), nonfatal reinfarction in 12 (6%), and coronary artery bypass graft surgery in nine (4%). An abnormal postexercise SBP response was defined as the ratio of SBP at 3 minutes of recovery to peak exercise SBP of 0.9 or more, on the basis of the cutoff point with the highest sensitivity and specificity to predict cardiac events. An abnormal postexercise SBP response occurred in 90 patients (42%). Patients with an abnormal postexercise SBP response had more exercise-induced myocardial ischemia. more left ventricular impairment, and more extensive coronary artery lesions than those without. Cox proportional hazards model demonstrated that the abnormal postexercise SBP response was ranked first in ability to predict cardiac death (p = 0.025, relative risk 15.41). Bypass surgery was associated with an abnormal postexercise SBP ratio (p less than 0.05). Nonfatal reinfarction could not be predicted by any clinical or exercise variables. In conclusion, an abnormal postexercise SBP response could be useful for predicting cardiac death and the need for bypass surgery after myocardial infarction. This response is probably the result of myocardial ischemia and left ventricular impairment.

Impaired blood pressure response to exercise in patients with coronary artery disease: possible contribution of attenuated reflex vasoconstriction in non-exercising muscles

Eighteen patients with coronary artery disease were divided into two groups according to whether their blood pressure decreased (eight, group 1) or increased (10, group 2) in response to treadmill exercise testing. Age and the extent and distribution of coronary artery disease were similar in the two groups. At rest, blood pressure, pulmonary artery wedge pressure, cardiac index, forearm vascular resistance, and oxygen consumption were similar in the two groups. During supine leg exercise on a bicycle ergometer mean blood pressure increased in group 2 but did not change in group 1. Increases in cardiac index, pulmonary artery wedge pressure, and oxygen consumption during leg exercise were not significantly different in the two groups but forearm vascular resistance increased less in group 1 than in group 2. There was a positive correlation between the magnitude of the change in mean blood pressure and change in forearm vascular resistance during leg exercise. The impaired response of blood pressure to leg exercise in group 1 was not the result of a failure of the cardiac index to increase. The results suggest the possibility that attenuation of reflex vasoconstriction in non-exercising muscles may contribute to the impaired response of blood pressure to exercise in patients with coronary artery disease.

Exercise-induced hypotension in a male population. Criteria, causes, and prognosis

The objective of this study was to demonstrate the causes, optimal definition, and predictive value of exercise-induced hypotension occurring during treadmill testing. This study included all patients referred for clinical reasons to the Long Beach Veterans Administration Medical Center treadmill laboratory and then followed for a 2-year period for cardiac events. The population consisted of 2,036 patients who underwent testing from April 4, 1984, to May 7, 1987, 131 of whom exhibited exercise-induced hypotension (6.4%). We found that exercise-induced hypotension is usually related to myocardial ischemia or myocardial infarction, is best defined as a drop in systolic blood pressure during exercise below the standing preexercise value, and indicates a significantly increased risk for cardiac events (3.2-fold, p less than 0.005). This increased risk was not found in those having no previous myocardial infarction or no signs or symptoms of ischemia during the exercise test, and the increased risk was also not found in those undergoing a treadmill test within 3 weeks after a myocardial infarction. Exercise-induced hypotension appeared to be reversed by revascularization procedures, but confirmation of a beneficial effect on survival requires a randomized trial. The clinical importance of this study is that we have demonstrated that a drop in systolic blood pressure below standing preexercise values during treadmill testing indicates an increased risk for cardiac events except in certain subsets of patients.

Exercise testing: uses and limitations considering recent studies

Accurate use and interpretation of exercise test results depend on an understanding of physiologic principles, meticulous attention to proper methodology, and realization of the appropriate applications and limitations of testing. Understanding the relationship between myocardial and ventilatory oxygen consumption and exercise test variables will aid in the diagnosis and prognostic evaluation. Use of proper methodology in preparing the patient, performing the examination, and interpreting the results is critical to obtaining the maximum information with maximum safety for each individual patient. Improvements in methodology including the use of the Borg scale to estimate individual effort, abandonment of the predicted maximum heart rate, and the increased use of ventilatory oxygen uptake measurements should be applied. Exercise capacity should not be reported in total time but rather as the VO2 or MET equivalent of the workload achieved. This permits the comparison of the results of many different exercise testing protocols. The most useful exercise ECG variable for the diagnosis of coronary artery disease remains the ST segment shift. Unfortunately, it is not as helpful in localizing myocardial ischemia. Diagnostic accuracy can be improved by adjusting ST depressions for exercise-induced heart rate increase. Accuracy can be further increased by combining ECG, clinical, and radionuclide variables in probabilistic formulas that retain the independent diagnostic information from each variable and accurately predict disease probability. To avoid errors in clinical decision making, care must be used to insure that the mathematical formula used was derived from a population of patients that is similar to those being tested. The clinical applications for exercise testing include diagnosis of patients with chest pain syndromes, determination of disease severity, and prognosis in patients with known coronary artery disease, evaluation of arrhythmias, screening of asymptomatic patients, and evaluation of medical, surgical, and angioplastic therapy for coronary disease. In spite of studies involving thousands of patients, controversy exists regarding the diagnostic power of exercise testing. The large differences in reported accuracies are largely due to methodologic problems that have been encountered by various investigators. Clinicians should be made aware of these problems when reading the literature on ECG and radionuclide exercise testing. Such awareness will help them understand the limitations of these noninvasive procedures.(ABSTRACT TRUNCATED AT 400 WORDS)

The prognostic value of the exercise test

Numerous investigators have demonstrated that responses to exercise testing enable prediction of the severity of underlying coronary disease and the patient's prognosis. However, exercise testing cannot predict angiographic findings or a poor prognosis with absolute certainty. Because survival can only be improved in specific clinical subsets of patients, it is important to carefully select for catheterization those in whom intervention can improve both quality and quantity of life. To deliver cost-effective health care, an effort has been made to use decision analysis to select those who should undergo cardiac catheterization. Decision analysis depends on reliable information regarding the predictive accuracy of the exercise test. Thus, this review is timely. Recent studies investigating the prognostic value of the exercise test are reviewed in this monograph. Patients include those recovering from a recent myocardial infarction (MI), those with stable coronary heart disease (including studies that have considered coronary angiographic findings, cardiac end points, and/or improved survival with coronary artery bypass surgery), and apparently healthy individuals. From this review, we conclude that silent ischemia induced by exercise testing in apparently healthy men is not as predictive of a poor outcome as once thought. Also, the use of the exercise test for screening is even more misleading than previously appreciated because of the higher rate of false positive results. Review of the 24 available studies of exercise testing in post-MI patients demonstrates that clinical judgment can be used to identify the high-risk patients, and that ST-segment shifts are not as predictive of high risk as an abnormal systolic blood pressure response or a poor exercise capacity. In patients with stable coronary heart disease, studies considering angiographic findings, cardiac events, and the differential outcome of coronary artery bypass surgery as compared with medical therapy have shown the exercise test to have prognostic power. From this perspective, it is obvious that there is much information supporting the use of exercise testing as the first noninvasive step after the history, physical examination, and resting electrocardiogram in the prognostic evaluation of patients with coronary artery disease. It accomplishes both purposes of prognostic testing: to provide information regarding the patient's status, and to help make recommendations for optimal management. The exercise test results help us make reasonable decisions for selection of patients who should undergo coronary angiography-including quality-of-life issues.(ABSTRACT TRUNCATED AT 400 WORDS)

Cost-effectiveness of screening strategies for left main coronary artery disease in patients with stable angina

To define optimal strategies for screening for left main coronary artery disease (LMCAD), the authors evaluated the cost-effectiveness of exercise tolerance testing and cardiac catheterization in patients with mild stable chest pain, such as patients with definite or probable angina in the Coronary Artery Surgery Study registry (prevalence of LMCAD = 9%). Performance characteristics of the exercise test, operative mortality, long-term survival rates, and rates of crossing over to surgical therapy for patients initially managed with medical therapy were derived from pooled literature data; cost estimates were based on local charge data. Strategies using the exercise test to identify candidates for catheterization were associated with longer life expectancies than either the conservative strategy in which patients would be observed or the more aggressive strategy in which all patients would undergo coronary angiography. The most cost-effective option was to screen patients with an exercise test and to perform catheterization in patients with greater than or equal to 2 mm of ST-segment change. Compared with a strategy of catheterization for greater than or equal to 3 mm of ST-segment change only, this strategy increased life expectancy at marginal costs per year of life saved ranging from $11,263 to $18,100 for 40- to 70-year-old patients, respectively, while, compared with a strategy of observation unless symptoms worsened, its incremental cost-effectiveness was $6,510 to $12,428 per year of life saved. Thus, screening patients with stable chest pain syndromes with exercise tests and performing catheterization for patients with greater than or equal to 2 mm of ST-segment change has cost-effectiveness comparable to that of the treatment of moderate diastolic hypertension.

Silent myocardial ischemia: II. Prognosis and implications for the clinical assessment of patients with coronary artery disease

Myocardial ischemia is known to be a strong independent predictor of cardiac events. New data suggest that the presence of silent ischemia, like symptomatic ischemia, is indicative of an increased risk of future cardiac events. Ordinarily, patients with suspected or known coronary artery disease are evaluated first for the presence of myocardial ischemia by performing exercise ECG, used as a test of both diagnosis and prognosis. In those patients who have an "intermediate" probability of cardiac event after exercise ECG, prognostic assessment may be enhanced, by using either radionuclide stress testing, to assess the extent and severity of potentially inducible ischemia, or ambulatory ECG, to assess the frequency and duration of spontaneously occurring ischemia. The indications for testing and type of test to be used are highly dependent on a number of clinical factors, not the least of which are the nature of the population to be evaluated and the exercise ECG response. We have proposed an overall approach for prognostic testing that considers the potential strengths and limitations of each form of testing. This potential approach now requires prospective evaluation.

Anatomic and functional significance of a hypotensive response during supine exercise radionuclide ventriculography

The significance of a decline in systolic blood pressure (BP) during supine exercise was examined in 820 patients who underwent both supine exercise gated equilibrium radionuclide ventriculography and coronary angiography. Twenty-seven patients, 3% of the study population, had a decrease in systolic BP at peak exercise of more than 10 mm Hg from the systolic BP at rest. Other indicators of ischemia--angina, ST-segment depression, a decrease in ejection fraction and wall motion abnormality during exercise--were present frequently but not uniformly in these patients. Although most patients had a decline in ejection fraction and a new wall motion abnormality with exercise, 4 patients had an increase in ejection fraction with exercise without any regional wall motion abnormalities. Coronary angiography in the 27 patients with systolic hypotension demonstrated severe coronary artery disease (CAD). Twenty-two patients (81%) had 3-vessel or left main CAD. Twenty of these 22 patients with 3-vessel CAD had at least 2 arteries with 90% or more diameter stenoses. Systolic hypotension during supine exercise radionuclide angiography is infrequent, usually associated with evidence of global and regional left ventricular dysfunction, and a marker of very severe CAD.

Prospective evaluation of a clinical and exercise-test model for the prediction of left main coronary artery disease

In a multivariate logistic regression analysis of data from 508 patients, only two clinical factors, age and typicality of pain, were independently significant predictors of left main coronary artery disease. The resulting multivariate equation was prospectively applied to another 370 patients to derive pre-exercise-test (ETT) probabilities of left main coronary artery disease, and these pre-ETT probabilities were combined with literature-derived likelihood ratios for various ETT findings to derive post-ETT probabilities. This model, which can be displayed in simple graphic form, accurately predicted the probability of left main coronary artery disease when prospectively evaluated in this independent validation set of patients. The likelihood of left main coronary artery disease was 16% when the ETT increased the probability, and 4% when it decreased the probability (p less than 0.001). While 48% of patients had mid-range (5-15%) probabilities of left main coronary artery disease before the ETT, only 24% fell into this range of probabilities after the ETT (p less than 0.0001), as ETT results moved patients into higher and lower probability ranges. Thus, probability of left main coronary artery disease can be calculated from clinical and ETT data with this model. These estimated pre- and post-ETT probabilities of left main coronary artery disease may aid in the selection of patients for noninvasive testing or for cardiac catheterization.

Determinants of abnormal blood pressure response to exercise in coronary artery disease

This study assessed the determinants of exercise-induced abnormal systolic blood pressure (BP) response in 127 patients with documented coronary artery disease (CAD) who underwent exercise thallium-201 scintigraphy. Three types of systolic BP response to exercise were identified: an increase by more than 20 mm Hg (group I, n = 74); an increase by 20 mm Hg or less (group II, n = 36); and a decrease of at least 10 mm Hg (group III, n = 17). The 3 groups were not significantly different in age, gender or medications. The number of segments with perfusion defects was significantly higher in groups II and III than group I (group III, 2.9 +/- 1.5; group II, 2.9 +/- 2.1; and group I, 1.8 +/- 1.4, p = 0.009). Prior myocardial infarction, abnormal left ventricular ejection fraction, and multivessel CAD were more common in group III than in groups I and II. Stepwise discriminant analysis of 15 relevant clinical, angiographic and exercise scintigraphic descriptors showed that the number of thallium perfusion defects, abnormal LV ejection fraction at rest and multivessel CAD to be important predictors of hypotensive BP response. Multivariate analysis, however, showed that the number of thallium perfusion defects was the only important predictor of the hypotensive response. Thus, it is the functional significance of CAD assessed by the extent of thallium perfusion abnormalities rather than the extent of CAD or left ventricular dysfunction at rest that determines the systolic BP response to exercise.

Functional and anatomic correlates of markedly abnormal stress tests

The functional state and coronary anatomy of 120 patients evaluated primarily because of a markedly positive ischemic exercise stress test (greater than 2 mm ST depression) is presented. Twenty-seven patients were asymptomatic (group A), 36 patients (group B) had type I angina (Canadian classification) and 57 patients (group C) had angina with only minor limitations (type II angina). All patients underwent exercise stress testing (Bruce protocol) within 2 months of cardiac catheterization. No significant intergroup differences were observed in exercise variables including time of onset of ischemia, maximal heart rate achieved, rate-pressure product, duration of exercise or mean change in blood pressure. Two patients in group A had normal coronary arteriograms. Comparison of the remaining asymptomatic patients in group A with patients in groups B and C revealed no significant differences in the number of coronary arteries involved, main left coronary artery disease, coronary score or the frequency of collateral circulation. In group A, 18% of collateral vessels were in jeopardy compared with 52% in groups B and C (p less than 0.05). Triple vessel disease was present in 57% and left main coronary artery disease in 16% of the total group. The only exercise variable useful in identifying patients with severe coronary disease was an abnormal exercise blood pressure response. This study indicates that a markedly ischemic stress test, regardless of the functional state of the patient, identifies patients, including those without symptoms, who have severe coronary disease.(ABSTRACT TRUNCATED AT 250 WORDS)