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This study prospectively evaluated 75 consecutive patients (mean age 69 [+ or -] 9 years) undergoing major vascular surgery to test the hypothesis that dobutamine stress echocardiography can be used to predict perioperative cardiac events. A positive test was defined as a new or worsening wall motion abnormality in at least 2 of 18 wall segments. Up to 40 [mu]g/kg/min of dobutamine was administered. All readings were done by physicians unaware of the patients' symptoms and electrocardiographic response. In addition, physicians caring for the patients were unaware of the test result. End points of the study were unstable angina with documented electrocardiographic changes, nonfatal myocardial infarction or cardiac death. The perioperative ischemic event rate was 7% (5 of 75 patients). Three patients developed unstable angina and 2 sustained nonfatal myocardial infarctions. All of these patients had positive results on dobutamine stress echocardiography (sensitivity 100%). However, 22 patients who also had positive results on dobutamine stress echocardiography did not have perioperative events (specificity 69%). The corresponding positive predictive value was 19%. None of the 48 patients who had negative results on dobutamine stress echocardiography had events (negative predictive value 100%). In conclusion, dobutamine stress echocardiography can be used to predict perioperative events with great sensitivity, but its positive predictive value in this patient population is low, likely due to the low incidence of perioperative events in patients with known coronary artery disease and the imperfect specificity of dobutamine stress echocardiography in identifying significant coronary stenosis. Dobutamine stress echocardiography is most useful in this setting when negative, because it predicts safety from complications with confidence. (Am J Cardiol 1993;72:602-607) Despite the diversity of cardiac tests and therapies currently available, perioperative cardiac complications remain the leading cause of death after anesthesia and surgery.[1] Multiple studies have shown that patients undergoing noncardiac vascular surgery are at particularly high risk of having perioperative cardiac events, with an event rate as high as 10 to 15% in some published reports.[2-5] Tests using dipyridamole or exercise with or without radionuclide imaging have become widely used as preoperative screening tools to identify patients who may require additional cardiac intervention before proceeding with vascular surgery. Vasodilator (dipyridamole) radionuclide imaging has become an important diagnostic test in patients who are unable to exercise, which is the case for a majority of patients requiring vascular surgery. More recently, dobutamine stress echocardiography has proven to be a promising and sensitive noninvasive test for detecting significant coronary artery disease.[6-12] However, the role of dobutamine stress echocardiography in the preoperative evaluation of patients requiring vascular surgery has not been well established. Studies that have examined the predictive value of dobutamine stress echocardiography in patients requiring vascular surgery are few in number, unblinded, and mostly retrospective in design or selective to include higher risk patients.[13,14] The aim of this study was to determine the efficacy and safety of dobutamine stress echocardiography in predicting perioperative cardiac morbidity and mortality in unselected noncardiac patients requiring vascular surgery using a prospective, double-blind study design. METHODS Patient population: One hundred forty-two consecutive patients scheduled to have elective vascular surgery between September 1991 and June 1992 were prospectively screened. Patients requiring emergency surgery and those requiring vascular surgery for nonischemic vascular disease were excluded. In addition, all 14 patients undergoing elective carotid endarterectomy performed by one of 2 participating surgeons were excluded because of a preference of that surgeon. Twenty-eight of the remaining 107 patients were either unwilling to give consent or were unable to undergo dobutamine echocardiography due to scheduling constraints. Four patients who gave informed consent and underwent dobutamine echocardiography subsequently did not have their scheduled vascular surgery during the study period and therefore were excluded from further analysis. Results of dobutamine stress echocardiography did not influence the decision against surgery in any of these patients. The remaining 75 patients composed the study group. Each patient had a detailed history and physical examination performed by one of the research physicians. Historical and clinical predictors of perioperative cardiac events as previously outlined by Goldman[15] and Detsky[16,17] and their co-workers were collected for each patient before dobutamine infusion. Dobutamine echocardiograms: Echocardiographic testing was performed 6 [+ or -] 11 days (mean [+ or -] SD) before the vascular procedure and frequently the day preceding the vascular surgery (range 1 to 62 days). Patient's medications were not adjusted before the dobutamine infusion. Baseline 2-dimensional echocardiograms (Sonos 1000, Hewlett Packard Company, Andover, Massachusetts) were performed on all patients. After informed consent was obtained, an infusion of dobutamine was begun at a dosage of 5 [mu]g/kg/min and was increased every 3 minutes to 10, 15, 20, 30, and maximally 40 [mu]g/kg/min, as tolerated. A 3-lead electrocardiogram and 2-dimensional echocardiogram were continuously monitored for ischemic changes. In addition, blood pressure and 12-lead electrocardiograms were obtained every 3 minutes before any dosage increase. A clinical decision to increase the dose was made by the physician based on lack of evidence of ischemia and the patient's ability to tolerate the infusion. Atropine (0.5 mg intravenously) was administered at the end of the 15 [mu]g/kg/min dose if the heart rate had not increased by [greater than or equal to]25% over baseline and again at the end of the 20 [mu]g/kg/min dose if the heart rate had not increased by [greater than or equal to]50% over baseline or [greater than or equal to]85% of age-predicted maximal heart rate. Continuous 2-dimensional echocardiograms were recorded throughout the dobutamine infusion. Digital cine-loops (GTI/Freeland Inc., Louisville, Colorado) of 4 standard stress echocardiographic views were acquired before the start of the dobutamine infusion, at the end of the 5 [mu]g/kg/min dose, and at peak infusion. A cardiologist experienced in reading >100 stress echocardiograms interpreted all of the studies. The reviewer was unaware of the symptomatic, hemodynamic and electrocardiographic responses during dobutamine infusion, as well as any historical information about the patients. Test interpretation was based on the review of continuous echocardiographic videotape and the paired baseline and peak dose cine-loops. For purposes of this study, the clinical response and electrocardiographic response to dobutamine infusion were not considered in the interpretation of the test results. Regional wall motion was scored using a standard 18-segment system. A test was defined as positive if either a new or worsening wall motion abnormality developed in [greater than or equal to]2 of 18 segments. Regions that were hypokinetic at baseline and became akinetic with dobutamine were considered positive for ischemia. However, regions that were akinetic at baseline and became dyskinetic with dobutamine infusion were not considered ischemic unless [greater than or equal to]2 adjacent zones also developed new or worsening wall motion abnormalities. Although the results of the baseline 2-dimensional echocardiogram were provided to the surgeon and other physicians caring for the patient, the results of the dobutamine infusion were not revealed and therefore did not affect any clinical decisions regarding the intended vascular procedure. Periodic monitoring: Patients were followed daily through their hospital course until discharge. Serum creatinine kinase levels with MB fractions and 12-lead electrocardiograms were obtained daily for the first 3 postoperative days in all patients and when symptoms or signs suggesting cardiac ischemia developed. Before discharge, a 2-dimensional echocardiogram was repeated and compared with the preoperative baseline echocardiogram. Identification of perioperative ischemic events depended on rigidly defined criteria. The following end points were considered: ischemic cardiac death, nonfatal myocardial infarction and unstable angina. Nonfatal myocardial infarction was diagnosed if [greater than or equal to]2 of the 4 following criteria were met: (1) >30 minutes of chest discomfort resembling angina, (2) electrocardiographic changes of ST-segment elevation with subsequent new Q-wave formation or T-wave inversions, (3) elevated creatinine kinase levels (>243 IU/liter for men, >122 IU/liter for women) with MB fraction >5%, or (4) new resting wall motion abnormality in [greater than or equal to]2 of 18 segments on the predischarge 2-dimensional echocardiogram compared with the preoperative resting echocardiogram. Unstable angina was diagnosed only if all 3 of the following criteria were met: (1) chest discomfort occurring at rest, (2) [greater than or equal to]1 mm of ST-segment depression in [greater than or equal to]2 lea and (3) relief of chest discomfort with antianginal medicines. Statistical analysis: Perioperative cardiac events and clinical as well as dobutamine predictors of perioperative ischemia were compared using chi-square analysis with the appropriate degrees of freedom for categorical variables. The Student's t test was used for continuous variables including clinical index scores as defined previously by Goldman and Detsky. All p values are single-tailed. Statistical significance was defined at the 5% level (p [less than or equal to]0.05). Variables examined from the dobutamine stress echocardiography test included the presence of resting wall motion abnormalities, the development of chest discomfort, electrocardiographic changes, and the presence of new or worsening regional wall motion abnormalities with dobutamine infusion. RESULTS Patient characteristics (Table I): The mean age of the patients was 68 [+ or -] 9 years and 60% were men. Twenty-eight patients (35%) had a previous history of myocardial infarction and 20 patients (25%) had a history of previous coronary artery bypass surgery. Sixty-three patients (80%) reported either past or current cigarette use, 22 patients (25%) had a history of diabetes requiring medication, and 56 patients (71%) had a history of hypertension on medication. Fifteen patients (19%) were taking a [beta] blocker at the time of dobutamine echocardiography. Operations were performed on the lower extremities in 47 patients (60%), the abdominal aorta in 21 (27%), the carotid artery in 10 (13%), and the axillary artery in 1 (1%). [TABULAR DATA I OMITTED] Of the 4 patients who underwent dobutamine echocardiography and were subsequently excluded from analysis because vascular surgery was not performed, 2 patients had surgery postponed because of unrecognized medical illnesses (1 with acute renal failure and 1 with newly diagnosed lung carcinoma), 1 patient decided against surgery, and 1 patient died from cardiac arrest on his third hospital day while awaiting surgery. In this last patient, dobutamine echocardiography performed 2 weeks before admission newly demonstrated a dilated hypocontractile left ventricle on the resting echocardiogram as well as an ischemic response to dobutamine infusion. Attempts to optimize the patient's condition before his vascular surgery failed and the patient died several days after admission. Dobutamine echocardiography (Table II): All patients tolerated the dobutamine infusion without any serious complications. Sixty-nine patients (88%) reached a peak infusion rate of 40 [mu]g/kg/min. Forty-two patients (54%) received atropine during the dobutamine infusion. Twelve (86%) of the 14 patients taking [beta] blockers at the time of the study received atropine compared with 30 (46%) of the 65 patients not taking a [beta] blocker (p Sixteen patients had adverse effects from the dobutamine infusion. Nine patients (11%) developed hypotension tension with dobutamine defined as a [greater than or equal to] 20 mm Hg decrease from baseline systolic blood pressure or absolute value of [less than or equal to]85 mm Hg necessitating discontinuation of the infusion. In only 1 of these patients was hypotension symptomatic and in all patients blood pressure returned to the baseline value after discontinuation of the dobutamine infusion without additional treatment. Seven patients (8%) had other significant adverse effects from the dobutamine infusion precluding its continuation. These included 3 patients with systolic blood pressure [greater than or equal to]240 mm Hg, 1 patient with shortness of breath and increased left ventricular outflow tract gradient, 1 patient unable to continue on his left side, 1 patient with uncontrollable shaking, and 1 patient with atrial fibrillation. All patients with a hypertensive response to dobutamine had a longstanding history of hypertension, were hypertensive at baseline, and returned to baseline blood pressure after discontinuation of the infusion without any symptoms related to blood pressure elevation. The patient who developed atrial fibrillation had a previous history of intermittent atrial fibrillation, remained asymptomatic when atrial fibrillation developed during the dobutamine infusion, and converted spontaneously 3 days later without any adverse sequelae. Dobutamine echocardiography demonstrated ischemia in 27 of the 75 patients (36%) who underwent vascular surgery. Only 3 of the 9 patients (33%) who developed chest discomfort also had new or worsening wall motion abnormalities with dobutamine infusion. Five of the 8 patients (63%) who developed electrocardiographic changes characterized by [greater than or equal to]1 mm of horizontal to downsloping ST depressions in [greater than or equal to]2 leads had dobutamine-induced wall motion abnormalities. Perioperative cardiac events: Perioperative events occurred in 5 patients; 2 patients sustained myocardial infarctions and 3 developed unstable angina. New or worsening regional wall motion abnormalities appeared in all 5 patients with perioperative cardiac events (sensitivity 100%). However, 22 of the 70 patients (31%) without perioperative cardiac events also had an ischemic response to dobutamine infusion by wall motion abnormality criteria (specificity 69%). This corresponds to positive and negative predictive values of 19 and 100%, respectively. Additional information obtained from patient histories and dobutamine infusions in general did not predict perioperative cardiac events, with the exception of dobutamine-induced electrocardiographic changes. Mean Detsky and Goldman scores also were not different in the 2 groups (Table 1). Table II illustrates that the peak dose of dobutamine achieved, the peak rate-pressure product attained, and the development of hypotension were similar in those who had events or new or worsening wall motion abnormalities compared with those who did not. Wall motion abnormalities on the resting echocardiogram were identified in a similar percentage of patients who had perioperative cardiac events versus those who did not (Table III). Thus, the presence of resting wall motion abnormalities did not predict perioperative cardiac events in our study. Chest discomfort with infusion also was not predictive of either perioperative cardiac events or the development of new or worsening wall motion abnormalities. However, ischemic electrocardiographic changes during dobutamine infusion were seen in 2 of 5 patients (40%) with perioperative cardiac events compared with 6 of 70 patients (9%) who remained event free (p [less than or equal to]90.05). This corresponds to a sensitivity of 40% and specificity of 91%. [TABULAR DATA III OMITTED] DISCUSSION The estimated number of patients undergoing noncardiac vascular surgery who are at risk for perioperative cardiac morbidity and mortality is 7 to 8 million annually in the United States.[18] Predicting which patients may be at particularly high risk would be important, since perioperative cardiac events are the leading cause of death following noncardiac surgery. Several methods for estimating perioperative cardiac risk using clinical data have been devised such as the Goldman criteria and the multifactorial risk index published by Detsky et al. However, proven clinical preoperative predictors of perioperative cardiac morbidity and mortality are few and essentially limited to myocardial infarction within 6 months of the anticipated surgery and the presence of congestive heart failure. Most other conventional preoperative predictors, including many of those quoted by Goldman and Detsky, are frequently used but remain controversial.[1] In addition, the Goldman and Detsky indexes were originally applied to a group of patients with a relatively low prevalence of coronary artery disease. Applying the same clinical criteria to vascular surgery patients who have a high prevalence of coronary disease has never been fully examined. Risk stratification using exercise treadmill testing with or without radionuclide imaging and vasodilator radionuclide cardiac imaging provides additional proven and sensitive noninvasive evaluation of perioperative cardiac risk. In particular, the prognostic value of dipyridamole thallium-201 imaging in patients undergoing noncardiac vascular surgery has been studied by many groups and recently summarized.[19-23] Dipyridamole thallium-201 is highly sensitive in screening for perioperative events (sensitivity, 90 to 100%), but its positive predictive value in these studies is variable and ranges from 14 to 50%. More recent prospective data have even questioned the predictive potential of dipyridamole thallium-201 imaging as a preoperative screening test.[24] In addition, the prolonged length of thallium studies, cost and availability of tracers, technician time, and radiation exposure are some shortcomings of radionuclide imaging. Dobutamine echocardiography, although in its infancy, has been shown in multiple studies to be sensitive and specific in diagnosing significant coronary artery disease (Table IV). In these studies, the peak dose used ranged from 20 to 40 [mu]g/kg/min, no atropine was administered, and the average rate-pressure product attained was 15,500. In contrast, most of our patients received dobutamine at a peak dose of 40 [mu]g/kg/min, over one half received atropine, and the average rate-pressure product achieved was approximately 22,000. Because the sensitivity of dobutamine echocardiography for detecting coronary artery disease is enhanced by the addition of atropine,[25] the sensitivity for predicting perioperative cardiac events in our study should be equal to or greater than that of previous reports. Medications including [beta] blockers have been in general, and as in our study, continued before dobutamine infusion. Dobutamine at the doses used probably overcomes many of the [beta] blocking effects of existing medications. In our study, neither chest pain nor the development of hypotension with dobutamine infusion was associated with an ischemic response as evidenced by new or worsening wall motion abnormalities on 2-dimensional echocardiography. The nonspecific response of hypotension during dobutamine infusion has been previously demonstrated.[26] Rate-pressure product attained with dobutamine infusion was slightly lower in the group that had perioperative events than in patients who remained event free. This may be partially explained by the fact that, in general, lower dobutamine doses and less atropine were used in patients who developed wall motion abnormalities since the development of a new or worsening wall motion abnormality was one indication for discontinuing the infusion. All of our patients tolerated the infusion protocol without serious complications. However, a history of atrial fibrillation in a patient who is in normal sinus rhythm at the time of testing may be considered a relative contraindication to proceeding with the test. Rate-controlled atrial fibrillation at the time of the study should not confer any additional risk. [TABULAR IV DATA OMITTED] Three studies have examined the capabilities of dobutamine echocardiography to predict perioperative ischemic events in patients undergoing noncardiac surgery. In a retrospective review of 38 patients, 4 of 15 patients (27%) who had new dobutamine-induced wall motion abnormalities developed perioperative cardiac events, yielding a sensitivity of 100% and a positive predictive value of 21%.[14] Another study found that dobutamine echocardiography had a sensitivity of 91% and positive predictive value of 30%.[13] However, in this study, the patient population was selected because it included only aortic procedures. Additional limitations of this study were the inclusion of resting wall motion abnormalities that were unchanged with dobutamine infusion as positive tests and the open availability of the dobutamine infusion results to all cardiologists before the intended surgery. Finally, a study published in abstract form demonstrated dobutamine echocardiography to be 95% sensitive in predicting perioperative cardiac events. Our study prospectively evaluated 75 consecutive patients undergoing vascular surgery using a blinded protocol. Patients were studied on their usual medical regimens which often included [beta] blockers. We confined the study end points to exclude much less specific markers of perioperative ischemic events such as pulmonary edema, dysrhythmias or stable angina. In addition, because the value of dobutamine echocardiography for predicting perioperative events was unproven in a prospective manner at the time of patient enrollment, we did not reveal the results of the dobutamine echocardiograms to cardiologists or surgeons caring for the study patients. Therefore, the knowledge of the results did not alter clinical outcomes. Under these conditions, a low incidence of serious cardiac events occurred (7%). This may be partially explained by the rigid end point criteria used in our study, which would tend to identify a smaller number of perioperative events. We demonstrated that clinical parameters as indexed by Goldman and Detsky are not predictive of perioperative ischemic events in a vascular surgery population. In addition, resting wall motion abnormalities were not predictive of subsequent perioperative ischemic events. Since resting wall motion abnormalities do not necessarily reflect ischemia, it is sensible that their presence is of no statistical relevance in predicting perioperative ischemic events. Conclusions from the information obtained by dobutamine echocardiography in our study are similar to those previously enumerated. Ischemic electrocardiographic changes with dobutamine infusion were predictive of perioperative cardiac events. However, ST depression was only 40% sensitive. Conversely, new or worsening wall motion abnormalities are very sensitive indicators of perioperative events (sensitivity, 100%). Because the specificity of dobutamine echocardiography in detecting significant coronary stenosis is imperfect and because many patients who have ischemic coronary disease do not have perioperative cardiac events, the positive predictive value of dobutamine echocardiography is relatively low (19%) and comparable to the predictive value obtained by dipyridamole thallium-201 scintigraphy. The high negative predictive value of dobutamine echocardiography in our study is of more significance (i.e., the absence of new or worsening wall motion abnormalities with dobutamine infusion predicts safety from perioperative cardiac complications with confidence). The added sensitivity that may have resulted from higher infusion doses of dobutamine and the addition of atropine in our study potentially limited the positive predictive value of the test by decreasing its specificity. Dipyridamole and adenosine echocardiography have been shown to be less sensitive but more specific than dobutamine echocardiography in detecting significant coronary stenosis[7,27,28] and in 1 study of preoperative vascular surgery patients, the positive predictive value of dipyridamole echocardiography in detecting perioperative ischemic events was 78%.[29] Lower peak infusion doses of dobutamine without adjunctive atropine use may increase test specificity and yield similar predictive values compared with dipyridamole echocardiography in this population with a high prevalence of coronary disease but a low incidence of perioperative ischemic events. Peak dobutamine infusion doses of 40 [mu]g/kg/min and atropine may be best administered when diagnosing significant coronary stenosis, whereas lower infusion doses without atropine may yield higher test specificity without sacrificing sensitivity in prognostic situations such as the perioperative vascular surgery setting described. This has not been studied in a prospective fashion. Nevertheless, dobutamine echocardiography that does not reveal ischemia is a potent predictor of safety from perioperative cardiac complications. Lower dose dobutamine infusion may be even more ideal than other agents for screening surgical patients with stress echocardiography because high-dose dipyridamole and adenosine both have side effect profiles different from and less well tolerated than dobutamine protocols.[7] [1.] Mangano D. Perioperative cardiac morbidity. Anesthesiology 1990;72:153-184. [2.] Brown O, Hollier L, Pairolero P, Kazmier F, McCready R, Abdominal aortic aneurysm and coronary artery disease. Arch Surg 1981;116:1484-1488. [3.] Crawford E, Bomberger R, Glaeser D, Saleh A, Russel W. Aortoiliac occlusive disease. Factors influencing survival and function following reconstruction operation over a twenty year period. Surgery 1981;90:1055-1067. 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[9.] Cohen J, Trevor G, Ottenweller J, Binenbaum S, Wilchfort S, Kim C. Dobutamine digital echocardiography for detecting coronary artery disease. Am J Cardiol 1991;67:1311-1318. [10.] Mannering D, Cripps T, Leech G, Mehta N, Valantine H, Gilmour S, Bennett E. The dobutamine stress test as an alternative to exercise testing after acute myocardial infarction. Br Heart J 1988;59:521-526. [11.] Salustri A, Fioretti P, Pozzoli M, McNeill A, Roelandt J. Dobutamine stress echocardiography: its role in the diagnosis of coronary artery disease. Eur Heart J 1992; 13:70-77. [12.] Sawada S, Segar D, Ryan T, Brown S, Dohan A, Williams R, Finenberg N, Armstrong W, Feigenbaum H. Echocardiographic detection of coronary artery disease during dobutamine infusion. Circulation 1991;83:1605-1614. [13.] Lalka S, Sawada S, Dalsing M, Cikrit D. Sawchuk A, Kovacs R, Segar D, Ryan T, Feigenbaum H. Dobutamine stress echocardiography as a predictor of cardiac events associated with aortic surgery. J Vasc Surg 1992;15:831-840. [14.] Lane R, Sawada S, Segar D, Ryan T. Latka S, Williams R, Brown S, Armstrong W, Feigenbaum H. Dobutamine stress echocardiography for assessment of cardiac risk before noncardiac surgery. Am J Cardiol 1991;68:976-977. [15.] Goldman L, Caldera D, Nussbaum S. Multifactorial index of cardiac risk in non-cardiac surgical procedures. N Engl J Med 1977; 197:845-850. [16.] Detsky A, Abrams H, McLaughlin J, Drucker D, Sasson D, Johnston N, Scott J, Forbath N, Hilliard J. Predicting cardiac complications in patients undergoing noncardiac surgery. J Gen Int Med 1986;1:211-219. [17.] Detsky A, Abrams H, Forbath N. Scott J, Hilliard J. Cardiac assessment for patients undergoing noncardiac surgery. A multifactorial risk index. Arch Intern Med 1986:146:2131-2134. [18.] Weinstein M, Coxson P, Williams L, Pass T, Stason W, Goldman L. Forecasting coronary artery disease incidence, mortality, and cost: the coronary heart disease policy model. Am J Pub Health 1987;77:1417-1426. [19.] Leppo J, Plaja J, Gionet M, Tumolo J, Paraskos J, Cutler B. Noninvasive evaluation of cardiac risk before elective vascular surgery. J Am Coll Cardiol 1987;9: 269-276. [20.] Cutler B, Leppo J. Dipyridamole thallium 201 scintigraphy to detect coronary artery disease before abdominal aortic surgery. J Vasc Surg 1987;5:91-100. [21.] Boucher C, Brewster C, Darling R, Okada R, Strauss H, Pohost G. Determination of cardiac risk by dipyridamole-thallium image before peripheral vascular surgery. N Engl J Med 1985;312:389-394. [22.] Brown K. Prognostic value of thallium-201 myocardial perfusion imaging: a diagnostic tool comes of age. Circulation 1991;83:363-381. [23.] Eagle K, Singer D, Brewster D, Darling R, Mulley A, Boucher C. Dipyridamole-thallium scanning in patients undergoing vascular surgery. JAMA 1987;257: 2185-2189. [24.] Mangano D, London M, Tubau J, Browner S, Hollengerg M, Krupski W, Layug E. Massie B. Dipyridamole thallium-201 scintigraphy as a preoperative screening test: a reexamination of its predictive role. Circulation 1991;84:493-502. [25.] McNeill A, Fioretti P, El-Said E, Salustri A, Forster T, Roelandt J. Enhanced sensitivity for Detection of coronary artery disease by addition of atropine to dobutamine stress echocardiography. Am J Cardiol 1992;70:41-46. [26.] Mathias W, Marcovitz P, Armstrong W. implications of hypotensive response during dobutamine stress echocardiography. J Am Soc Echocardiogr 1991;4:280. [27.] Fung A, Gallagher K, Buda A. The physiologic basis of dobutamine as compared with dipyridamole stress interventions in the assessment of critical coronary stenosis. Circulation 1987;76:934-951. [28.] Previtali M, Lanzarini L, Ferrario M, Tortorici M, Mussini A, Montemartini C. Dobutamine versus dipyridamole echocardiography in coronary disease. Circulation 1991;83(suppl III):III-27-III-31. [29.] Tischler M, Lee T, Hirsch A, Lord C, Goldman L, Creager M, Lee R. Prediction of major cardiac events after peripheral vascular surgery using dipyridamole echocardiography. Am J Cardiol 1991:68:593-597. From the Cardiology Unit and the Center for Biomedical Ultrasound, in conjunction with the General Medicine Unit and the Department of Surgery, University of Rochester School of Medicine and Dentistry, Rochester, New York. This study was supported in part by the Sable Memorial Heart Fund Grant. Manuscript received December 31, 1992; revised manuscript received March 8, 1993, and accepted March 18. Address for reprints: James P. Eichelberger, MD, Department of Cardiology, University of Rochester School of Medicine and Dentistry, P.O. Box 679, Rochester, New York 14642.