Comparison of dobutamine stress echocardiography and 99m-technetium sestamibi SPECT myocardial perfusion scintigraphy for predicting extent of coronary artery disease in patients with healed myocardial infarction

Stress echocardiography expert consensus statement: European Association of Echocardiography (EAE) (a registered branch of the ESC)

Stress echocardiography is the combination of 2D echocardiography with a physical, pharmacological or electrical stress. The diagnostic end point for the detection of myocardial ischemia is the induction of a transient worsening in regional function during stress. Stress echocardiography provides similar diagnostic and prognostic accuracy as radionuclide stress perfusion imaging, but at a substantially lower cost, without environmental impact, and with no biohazards for the patient and the physician. Among different stresses of comparable diagnostic and prognostic accuracy, semisupine exercise is the most used, dobutamine the best test for viability, and dipyridamole the safest and simplest pharmacological stress and the most suitable for combined wall motion coronary flow reserve assessment. The additional clinical benefit of myocardial perfusion contrast echocardiography and myocardial velocity imaging has been inconsistent to date, whereas the potential of adding - coronary flow reserve evaluation of left anterior descending coronary artery by transthoracic Doppler echocardiography adds another potentially important dimension to stress echocardiography. New emerging fields of application taking advantage from the versatility of the technique are Doppler stress echo in valvular heart disease and in dilated cardiomyopathy. In spite of its dependence upon operator's training, stress echocardiography is today the best (most cost-effective and risk-effective) possible imaging choice to achieve the still elusive target of sustainable cardiac imaging in the field of noninvasive diagnosis of coronary artery disease.

Mechanisms of regional wall motion abnormalities in contrast-enhanced Dobutamine Stress Echocardiography

BACKGROUND

In the diagnosis of coronary artery disease (CAD) with Dobutamine Stress Echocardiography (DSE), regional wall motion abnormalities (RWMA) are assumed to indicate a perfusion deficit.

METHODS AND RESULTS

For a more particular examination of RWMAs, we compared simultaneous echo-contrast (Optisone)-enhanced DSE (0-40 microg/kg Dobutamine, 16-segment- model) and MiBi-SPECT in a prospective double-blinded study design in 69 non-selected consecutive patients (44 male, 25 female, age 64+/-12 years). Additionally, all patients were examined by coronary-angiography. The prevalence of significant CAD (stenosis >50% lumen diameter) was 52%. DSE had a sensitivity of 78% and a specificity of 66% for the detection of significant CAD with a positive and negative predictive value of 72 and 73%, respectively. Among 28 patients with significant CAD and positive DSE study (true positive), 78% displayed a corresponding perfusion deficit in MiBi-SPECT. Among 11 patients with a positive DSE study but no current significant coronary stenosis (false positive), 82% showed stress-induced RWMAs in the inferior/posterior region, 73% displayed left ventricular hypertrophy, 54% resting-ECG abnormalities and 45% resting-RWMA (3 previous MI, 2 previous CABG surgery). Among 8 patients with negative DSE study but significant coronary stenosis (false negative), 75% had a stenosis of the LCX, 63% displayed resting- WMA, 63% displayed left bundle branch block or ST-segment depression, 50% displayed only peripheral coronary stenosis, and DSE visualization was suboptimal in 38%.

CONCLUSION

This prospective study in non-selected patients shows that the majority of RWMAs in DSE are matched to a perfusion deficit detectable by nuclear imaging. Nevertheless, pre-existing cardiac abnormalities may also lead to stress-induced RWMA not associated with a perfusion deficit or mask a perfusion deficit upon DSE. Particularly in patients with LV hypertrophy, resting-RWMA, bundle branch block or ST segment depression, the predictive value of DSE may, therefore, be limited.

Prognostic value of stress Tc-99m tetrofosmin SPECT in patients with previous myocardial infarction: impact of scintigraphic extent of coronary artery disease

BACKGROUND

Our objective was to assess the prognostic value of the scintigraphic extent of coronary artery disease on stress technetium 99m tetrofosmin single photon emission computed tomography in patients with previous myocardial infarction.

METHODS AND RESULTS

We studied 383 patients (280 men and 103 women; mean age, 60 +/- 11 years) more than 3 months after an acute myocardial infarction by exercise bicycle or dobutamine (up to 40 mug . kg -1 . min -1 ) stress Tc-99m tetrofosmin myocardial perfusion tomography. Stress images were acquired 1 hour after stress, and rest images were acquired 24 hours after stress testing. An abnormal study was defined as one demonstrating a reversible or fixed perfusion abnormality. Myocardial segments were assigned to corresponding coronary arteries as follows: the apex, anterior wall, and anterior septum were assigned to the left anterior descending coronary artery; the posterolateral wall was assigned to the left circumflex artery; and the basal posterior septum and inferior wall were assigned to the right coronary artery. During a mean follow-up of 4.3 +/- 2.1 years, 48 cardiac events occurred (36 cardiac deaths and 12 nonfatal myocardial infarctions). Myocardial perfusion was normal in 51 patients, abnormal in a single-vessel distribution in 170 patients, and abnormal in a multivessel distribution in 162 patients. The annual cardiac event rates in these groups were 0.4%, 2.6%, and 4%, respectively. In a multivariate analysis model, independent predictors of cardiac events were diabetes mellitus (odds ratio [OR], 2.3; 95% confidence interval [CI], 1.4-4.5), history of congestive heart failure (OR, 2.7; 95% CI, 1.4-4), age (OR, 1.05; 95% CI, 1.01-1.08), and scintigraphic extent of coronary artery disease (OR, 4.2; 95% CI, 1.8-9.1).

CONCLUSION

Stress Tc-99m tetrofosmin myocardial perfusion imaging provides independent prognostic information for the risk stratification of patients with previous myocardial infarction. The event rate is directly related to the scintigraphic extent of coronary artery disease. Patients with normal perfusion have an excellent event-free survival rate.

Differential prognostic significance of peri-infarction versus remote myocardial ischemia on stress technetium-99m sestamibi tomography in patients with healed myocardial infarction

Peri-infarction and remote myocardial ischemia involve different myocardial substrates, but their differential clinical implications have not been previously studied. We assessed the differential prognostic significance of peri-infarction and remote ischemia during long-term follow-up in patients with healed myocardial infarction. We studied 345 patients (59 +/- 12 years old; 282 men) with previous myocardial infarction who demonstrated reversible perfusion abnormalities on exercise or dobutamine stress technetium-99m sestamibi tomography. Follow-up events for 5.5 +/- 2.6 years were 60 deaths (17%; 40 cardiac deaths) and 25 reinfarctions (7%). Reversible perfusion abnormalities were detected in the remote region in 129 patients (37%), the peri-infarction region in 142 patients (41%), and in both regions in 74 patients (21%). The annual rates of cardiac death in these groups were 1.2%, 2.8%, and 2.9%, respectively (p <0.01). The annual rates of reinfarction were 1%, 1.5%, and 0.9%, respectively (p = NS). In a multivariate analysis model, independent predictors of cardiac death were history of heart failure (risk ratio [RR] 2.8, 95% confidence interval [95% CI] 1.2 to 7), diabetes mellitus (RR 4.1, 95% CI 1.9 to 8.9), summed score at rest (RR 1.4, 95% CI 1.1 to 3.1), and peri-infarction ischemia (RR 2.6, 95% CI 1.1 to 6.1). Predictors of reinfarction were age (RR 1.03, 95% CI 1.01 to 1.07) and diabetes mellitus (RR 3.3, 95% CI 1.2 to 9.1). Peri-infarction ischemia assessed by stress technetium-99m sestamibi tomography is associated with a greater risk of cardiac death than is remote ischemia. The risk of reinfarction is not related to the location of ischemia.

Detection and clinical usefulness of a biphasic response during exercise echocardiography early after myocardial infarction

OBJECTIVE

The aim of this study was to determine the accuracy of exercise echocardiography (EE) for detecting infarct-related artery (IRA) stenosis and predicting functional recovery early after acute myocardial infarction (AMI).

BACKGROUND

Dobutamine stress echocardiography is widely used for identifying jeopardized myocardium. The clinical usefulness of a biphasic response detected during EE has never been investigated.

METHODS

A total of 114 consecutive patients with a first AMI and > or = 2 dyssynergic segments in the infarct-related territory underwent semi-supine continuous EE 6 +/- 2 days after AMI. Quantitative coronary angiography was performed in all patients after EE. A follow-up echocardiogram was obtained one month later.

RESULTS

Ninety-seven patients had significant (> or = 50%) IRA stenosis, and 26 had multivessel disease. Residual ischemia was identified in 77 patients (biphasic response in 62 and worsening response in 15). The sensitivity and specificity of ischemia during EE for predicting IRA stenosis were 75% and 76%, respectively. The sensitivity of a biphasic response was higher than the sensitivity of a worsening response (61% vs. 14%, p < 0.0001). Wall motion abnormalities induced in other vascular territories were specific (97%) and moderately sensitive (62%) for the detection of multivessel disease. Functional recovery was observed in 75 patients. Two independent variables predicted contractile recovery: contractile reserve during EE (p < 0.0001) and elective angioplasty of the IRA (p = 0.002). A biphasic response, but not sustained improvement, predicted reversible dysfunction (73% vs. 9%, p < 0.0001).

CONCLUSIONS

A biphasic response can be detected during exercise. Exercise echocardiography is an accurate tool for detecting IRA stenosis and predicting functional improvement early after AMI.

Utility and limitation of treadmill exercise echocardiography for detecting significant coronary stenosis in infarct-related arteries in patients with healed myocardial infarction

This clinical study examines the diagnostic accuracy of exercise echocardiography for detecting significant coronary stenoses in infarct-related arteries in patients with healed myocardial infarction. Quantitative coronary angiography and exercise echocardiography using treadmill testing were performed within 2 weeks of each other in 123 patients with a prior myocardial infarction. Coronary lumen diameter stenosis > or =50% by quantitative coronary angiography and the lack of a hyperdynamic response on exercise echocardiography was considered significant. For detection of infarct-related coronary lesions, treadmill exercise echocardiography was highly sensitive (91%) but less specific (59%) than for detection of non-infarct-related artery lesions. The 2 groups of patients with large and small infarct sites had similar sensitivity for detection of residual stenosis of the infarct-related artery (88% vs 96%, p = NS); however, the specificity of the small infarct sites for this purpose was significantly higher than that of the large infarct sites (86% vs 33%, p < 0.01). When remote ischemia was detected on exercise echocardiography, the specificity of exercise echocardiography was significantly lower (33% vs 70%, p < 0.05) than when remote ischemia was not present. Thus, although there is high sensitivity, the specificity of treadmill exercise echocardiography for detecting infarct-related artery lesions is limited. However, high specificity is maintained when the infarct size is small and/or remote ischemia is not present.

Dobutamine stress echocardiography versus quantitative technetium-99m sestamibi SPECT for detecting residual stenosis and multivessel disease after myocardial infarction

OBJECTIVE

To compare the relative accuracy of dobutamine stress echocardiography (DSE) and quantitative technetium-99m sestamibi single photon emission computed tomography (mibi SPECT) for detecting infarct related artery stenosis and multivessel disease early after acute myocardial infarction.

DESIGN

Prospective study.

SETTING

University hospital.

METHODS

75 patients underwent simultaneous DSE and mibi SPECT at (mean (SD)) 5 (2) days after a first acute myocardial infarct. Quantitative coronary angiography was performed in all patients after imaging studies.

RESULTS

Significant stenosis (> 50%) of the infarct related artery was detected in 69 patients. Residual ischaemia was identified by DSE in 55 patients and by quantitative mibi SPECT in 49. The sensitivity of DSE and mibi SPECT for detecting significant infarct related artery stenosis was 78% and 70%, respectively, with a specificity of 83% for both tests. The combination of DSE and mibi SPECT did not change the specificity (83%) but increased the sensitivity to 94%. Mibi SPECT was more sensitive than DSE for detecting mild stenosis (73% v 9%; p = 0.008). The sensitivity of DSE for detecting moderate or severe stenosis was greater than mibi SPECT (97% v 74%; p = 0.007). Wall motion abnormalities with DSE and transient perfusion defects with mibi SPECT outside the infarction zone were sensitive (80% v 67%; NS) and highly specific (95% v 93%; NS) for multivessel disease.

CONCLUSIONS

DSE and mibi SPECT have equivalent accuracy for detecting residual infarct related artery stenosis of >/= 50% and multivessel disease early after acute myocardial infarction. DSE is more predictive of moderate or severe infarct related artery stenosis. Combined imaging only improves the detection of mild stenosis.

Dobutamine stress myocardial perfusion imaging

In patients with limited exercise capacity and (relative) contraindications to direct vasodilators such as dipyridamole or adenosine, dobutamine stress nuclear myocardial perfusion imaging (DSMPI) represents an alternative, exercise-independent stress modality for the detection of coronary artery disease (CAD). Nondiagnostic test results (absence of reversible perfusion defects with submaximal stress) do occur in approximately 10% of patients. Serious side effects during DSMPI are rare, with no death, myocardial infarction or ventricular fibrillation reported in three DSMPI safety reports for a total of 2,574 patients. On the basis of a total number of 1,014 patients reported in 20 studies, the sensitivity, specificity and accuracy of the test for the detection of CAD were 88%, 74% and 84%, respectively. Mean sensitivities for one-, two- and three-vessel disease were 84%, 95% and 100%, respectively. The sensitivity for detection of left circumflex CAD (50%) was lower, compared with that for left anterior descending CAD (68%) and right CAD (88%). The sensitivity of predicting multivessel disease by multiregion perfusion abnormalities varied widely, from 44% to 89%, although specificity was excellent in all studies (89% to 94%). In direct diagnostic comparisons, DSMPI was more sensitive, but less specific, than dobutamine stress echocardiography and comparable with direct vasodilator myocardial perfusion imaging. In the largest prognostic study, patients with a normal DSMPI study had an annual hard event rate less than 1%. An ischemic scan pattern provided independent prognostic value, with a direct relationship between the extent and severity of the perfusion defects and prognosis. In conclusion, DSMPI seems a safe and useful nonexercise-dependent stress modality to detect CAD and assess prognosis.

The comparable diagnostic accuracies of dobutamine-stress and dipyridamole-stress echocardiographies: a meta-analysis

BACKGROUND

Dobutamine-stress and dipyridamole-stress echocardiographies are widely used for pharmacological stress echocardiography, with wide geographical variations.

OBJECTIVE

To assess whether evidence derived from the literature indicates or disapproves that either stress modality confers diagnostic superiority.

METHODS

We performed a meta-analysis of peer-reviewed literature of published trials with head-to-head comparison, on the same population, of high-dose (0.84 mg/kg) dipyridamole-stress versus high-dose (up to 40 micrograms/kg per min) dobutamine-stress echocardiography. Data from 12 studies performed in 12 institutions in seven countries were analysed. Angiographic information about 818 patients was considered.

RESULTS

The diagnostic accuracies of the two tests were similar (631 of 818, 77%, for dipyridamole versus 654 of 818, 80%, for dobutamine, NS). Overall sensitivities were 403 of 568 (71%) for dipyridamole and 437 of 568 (77%) for dobutamine (P < 0.05). Sensitivities for patients with single-vessel disease were 177 of 275 (64%) for dipyridamole and 203 of 275 (74%) for dobutamine (P < 0.05). Sensitivities for patients with multivessel disease were 162 of 203 (80%) for dipyridamole and 163 of 203 (80%) for dobutamine (NS). Specificities were 232 of 250 (93%) for dipyridamole and 217 of 250 (87%) for dobutamine (P < 0.05). Data from an additional 26 studies with dipyridamole alone and 47 studies with dobutamine alone were analysed. The diagnostic accuracies were 80% for dipyridamole (n = 2038 patients; 95% confidence interval 75-82%) and 82% for dobutamine (n = 4264 patients; 95% confidence interval 79-84%).

CONCLUSION

High-dose dobutamine-stress and high-dose dipyridamole-stress echocardiographies have comparable diagnostic accuracies, with a slightly higher sensitivity with dobutamine and a slightly higher specificity with dipyridamole.

Gender differences in the relation between ST-T-wave abnormalities at baseline electrocardiogram and stress myocardial perfusion abnormalities in patients with suspected coronary artery disease

The presence of ST-T-wave abnormalities in the resting electrocardiogram was reported as a predictor of coronary artery disease (CAD) and increased morbidity and mortality. However, the independent value of ST-T abnormalities for predicting the presence and severity of perfusion abnormalities during stress testing has not been studied in a homogenous patient group without known CAD. We evaluated the relation between resting ST-T abnormalities and myocardial perfusion abnormalities in 246 patients (age 59 +/- 13 years, 114 men and 132 women) without known CAD or previous myocardial infarction referred for evaluation of possible myocardial ischemia by dobutamine (up to 40 microg/kg/min) stress sestamibi or tetrofosmin single-photon emission computed tomographic imaging. Resting ST-T abnormalities were present in 123 patients, whereas 123 patients with normal resting electrocardiograms served as a matched control group. Abnormal myocardial perfusion (fixed or reversible perfusion defects) was detected in 72% of men with and in 35% of men without resting ST-T abnormalities (p <0.0001), whereas the prevalence of myocardial perfusion abnormalities was not different in women with and without resting ST-T abnormalities (27% vs 23%, p = NS). In the entire population, independent predictors of an abnormal perfusion by multivariate analysis of clinical characteristics and risk factors were male gender (p <0.001, chi-square 10.5) and resting ST-T abnormalities (p <0.05, chi-square 3). Separate analysis of patients based on gender revealed resting ST-T abnormalities as independent predictors of abnormal perfusion in men (p <0.05, chi-square 4) but not in women. Stress perfusion defect score was higher in men with than without ST-T abnormalities (887 +/- 545 vs 207 +/- 180, p <0.001). It is concluded that resting ST-T wave abnormalities are associated with a higher prevalence and severity of resting and dobutamine-induced myocardial perfusion abnormalities in men but not in women. Resting ST-T wave abnormalities are powerful predictors of compromised myocardial perfusion independent of other clinical risk factors of CAD in men.

Cost-effectiveness of stress-echocardiography

Because of constraints on the costs of providing medical care, cardiologists in the future will find themselves challenged to provide care for their patients in the most cost-effective manner possible. Although stress-echocardiography has been shown to compare favorably with other tests in diagnostic accuracy, data on cost-effectiveness are scarce. In this article, general concepts of cost-effectiveness as they relate to stress-echocardiography are reviewed and the available literature is summarized. Although definitive data are lacking, there is evidence to suggest that stress-echocardiography may prove to be cost-effective in several clinical situations.

Dobutamine-induced ST-segment elevation in patients without myocardial infarction

During dobutamine stress echocardiography, ST-segment elevation developed in 20 of 372 patients (5%) without previous myocardial infarction and was associated with a transient severe asynergy of the myocardial region corresponding to the site of ST elevation. In 17 of 19 patients, ST-segment elevation was associated with a critical stenosis of the ischemia-related coronary artery, whereas in 2 of 19 patients with no critical lesions of the ischemia-related artery, coronary vasospasm was the most likely mechanism of myocardial ischemia.

Optimal criteria for the diagnosis of coronary artery disease by dobutamine stress echocardiography

The diagnosis of coronary artery disease (CAD) on the basis of inducible ischemia in > or = 2, rather than 1, segments was suggested to improve specificity of dobutamine stress echocardiography (DSE). However, the impact of using these criteria on the sensitivity and accuracy of DSE was not studied. We studied the accuracy of DSE (up to 40 microg/kg/min) for the diagnosis of CAD in 290 patients with suspected myocardial ischemia using the criteria of > or = 1 and > or = 2 ischemic segments. Ischemia was defined as new or worsening wall motion abnormalities using a 16-segment model. Among the 85 patients without previous myocardial infarction, significant CAD was detected in 51 (60%). Sensitivity, specificity, and accuracy of DSE using > or = 1 ischemic segment were 73%, 85%, and 78%, respectively. Those using > or = 2 segments were 67%, 94%, and 78%, respectively (p = NS). Regional specificity improved by using > or = 2 segments (91% vs 96%, p <0.05) at the expense of an equivalent reduction in regional sensitivity (60% vs 44%, p <0.05), whereas the regional accuracy was similar (80% vs 79% for > or = 1 and > or = 2 segments, respectively). In the 205 patients with previous myocardial infarction, the criterion of ischemia in > or = 1 segment had a higher sensitivity and accuracy for overall diagnosis of CAD (75% vs 64%, p <0.05; 77% vs 68%, p <0.05), infarct-related CAD (64% vs 47%, p <0.005; 70% vs 57%, p <0.01), and remote CAD (74% vs 57%, p <0.005; 78% vs 69%, p <0.05) than the criterion of > or = 2 segments, respectively. It is concluded that in patients without previous myocardial infarction, the use of > or = 2 ischemic segments by DSE for the diagnosis of CAD does not improve the accuracy of DSE compared with the criterion of > or = 1 ischemic segment. Conversely, in patients with previous infarction the use of > or = 2 segments reduces the overall and regional sensitivity and accuracy without a significant improvement in specificity.

Noninvasive diagnosis of coronary artery stenosis in women with limited exercise capacity: comparison of dobutamine stress echocardiography and 99mTc sestamibi single-photon emission CT

OBJECTIVES

To compare the accuracy of dobutamine stress echocardiography (DSE) and simultaneous 99mTc sestamibi (MIBI) single-photon emission CT (SPECT) imaging for the diagnosis of coronary artery stenosis in women.

PATIENTS

Seventy women with limited exercise capacity referred for evaluation of myocardial ischemia.

METHODS

DSE (up to 40 microg/kg/min) was performed in conjunction with stress MIBI SPECT. Resting MIBI images were acquired 24 h after the stress test. Ischemia was defined as new or worsened wall motion abnormalities confirmed by DSE and as reversible perfusion defects confirmed by MIBI. Significant coronary artery disease was defined as > or = 50% luminal diameter stenosis.

RESULTS

DSE was positive for ischemia in 35 of 45 patients with coronary artery stenosis and in 2 of 25 patients without coronary artery stenosis (sensitivity = 78% CI, 68 to 88; specificity = 92% CI, 85 to 99; and accuracy = 83% CI, 74 to 92). A positive MIBI study for ischemia occurred in 29 patients with coronary artery stenosis and in 7 patients without coronary artery stenosis (sensitivity = 64% CI, 53 to 76; specificity = 72% CI, 61 to 83; and accuracy = 67% CI, 56 to 78 [p < 0.05 vs DSE]). In the 59 vascular regions with coronary artery stenosis, the regional sensitivity of DSE was higher than MIBI (69% CI, 62 to 77 vs 51% CI, 42 to 59, p < 0.05), whereas specificity in the 81 vascular regions without significant stenosis was similar (89% CI, 84 to 94 vs 88% CI, 82 to 93, respectively).

CONCLUSION

DSE is a useful noninvasive method for the diagnosis of coronary artery stenosis in women and provides a higher overall and regional diagnostic accuracy than dobutamine MIBI SPECT in this particular population.

Dobutamine-atropine stress myocardial perfusion SPECT imaging in the diagnosis of graft stenosis after coronary artery bypass grafting

OBJECTIVE

To assess the accuracy of dobutamine stress myocardial perfusion single photon emission computed tomographic imaging (SPECT) for the diagnosis of vascular stenosis after coronary artery bypass grafting (CABG).

BACKGROUND

Exercise thallium scintigraphy is a clinically useful method for the diagnosis of graft stenosis after CABG. Although dobutamine perfusion scintigraphy is an alternative method for the evaluation of patients with limited exercise capacity, its value in the diagnosis of vascular stenosis after CABG has not been studied.

METHODS

Dobutamine (up to 40 lg/kg/min)-atropine (up to 1 mg) stress test in conjunction with myocardial perfusion SPECT imaging (201T1 or 99m technetium sestamibi [MIBII) was performed in 71 patients (mean age 58 9 years, 57 men) with limited exercise capacity referred for evaluation of myocardial ischemia 3.7 3.5 years after CABG. Significant vascular stenosis was defined as >50% luminal diameter stenosis of a graft or a native nongrafted coronary artery and was predicted on the basis of reversible perfusion abnormalities.

RESULTS

Significant vascular stenosis was detected in 52 patients. Sensitivity, specificity, and accuracy of reversible perfusion defects at dobutamine SPECT for the overall diagnosis of vascular stenosis were 81%, confidence interval (CI) 72 to 90, 79%, CI 69 to 88, and 80%, CI 71 to 90, respectively. Significant vascular stenosis was detected in 73 arterial regions. Sensitivity, specificity, and accuracy of dobutamine SPECT for the diagnosis of regional vascular stenosis were 66%, CI 58 to 74, 83%, CI 76 to 89, and 74%, CI 67 to 81, respectively. Patients with multivessel stenosis had a higher number of ischemic segments (1.6 + 1.3 vs 1 + 1, P < .05) and ischemic perfusion score (3.2 2.7 vs 2.2 + 2.3, P < .05) than patients with single-vessel stenosis, respectively. Significant graft stenosis was detected in 67 graft regions. Sensitivity, specificity, and accuracy of dobutamine SPECT for the diagnosis of regional graft stenosis were 64%, CI 56 to 73, 85%, CI 78 to 91, and 74%, CI 66 to 82, respectively.

CONCLUSION

Dobutamine stress myocardial perfusion SPECT imaging is a useful method for the diagnosis of significant vascular stenosis after CABG in patients with limited exercise capacity.

Methodology, feasibility, safety and diagnostic accuracy of dobutamine stress echocardiography

Large numbers of patients referred for evaluation of chest pain are unable to perform adequate, diagnostic exercise testing. In these patients, dobutamine stress echocardiography (DSE) represents an alternative, exercise-independent stress modality. Apart from the approximately 5% of patients with an inadequate acoustic window, 10% of patients referred for this test have nondiagnostic (submaximal negative) test results. Serious side effects during or shortly after DSE are uncommon, with ventricular fibrillation or myocardial infarction occurring in approximately 1 of 2,000 studies. No deaths have been reported. On the basis of a total number of 2,246 patients, reported in 28 studies, the sensitivity, specificity and accuracy of the test for the detection of coronary artery disease (CAD) were 80%, 84% and 81%, respectively. Mean sensitivities for one-, two- and three-vessel disease were 74%, 86% and 92%, respectively. The sensitivity for detection of disease in the left circumflex coronary artery (55%) was lower, both compared with that for left anterior descending (72%) and right coronary artery disease (76%). The sensitivity of predicting multivessel disease by multiregion echocardiographic abnormalities varied widely, from 8% to 71%. In direct comparisons, DSE was superior to exercise electrocardiography and dipyridamole echocardiography and comparable to exercise echocardiography and radionuclide imaging. DSE is a useful, feasible and safe exercise-independent stress modality for assessing the presence, localization and extent of CAD.

Safety and feasibility of dobutamine-atropine stress testing in hypertensive patients

Dobutamine stress testing is increasingly used for the diagnosis and functional evaluation of coronary artery disease. The aim of this study was to assess the hemodynamic profile, safety, and feasibility of dobutamine stress testing in hypertensive patients. Dobutamine (up to 40 micrograms/kg per minute)-atropine (up to 1 mg) stress echocardiography was performed for the detection of myocardial ischemia in 1164 patients with limited exercise capacity (age, 60 +/- 12 years; 761 men); 446 patients were known to have hypertension. The test was considered feasible when 85% of the maximal heart rate and/or an ischemic end point (new or worsened wall motion abnormalities, ST segment depression, or angina) was achieved. No myocardial infarction or death occurred during the test. Dobutamine induced a significant increase of heart rate in patients with and without hypertension (59 +/- 25 and 63 +/- 23 beats per minute, respectively). Peak rate pressure product was similar in patients with and without hypertension (18,566 +/- 4584 and 18,230 +/- 4508). Hypotension (systolic pressure drop > 40 mm Hg) during the test was more frequent in hypertensive patients (7% versus 4% in normotensive, P < .05). Independent predictors of hypotension were baseline systolic pressure greater than 140 mm Hg (odds ratio, 6.9; 95% confidence interval, 3.4 to 14), older age (odds ratio, 1.04; 95% confidence interval, 1.01 to 1.07), and medication with calcium channel blockers (odds ratio, 1.8; 95% confidence interval, 1.1 to 3.5). The prevalence of ventricular tachycardia was similar (4.1%) in both groups. Episodes of 10 beats or more (0.06% of patients) were terminated promptly by intravenous metoprolol administration. Dobutamine stress testing was considered feasible in 91% of patients with and 92% of patients without hypertension. Dobutamine-atropine stress echocardiography is a safe and feasible method for the assessment of hypertensive patients referred for evaluation of myocardial ischemia. Despite the higher prevalence of dobutamine-induced hypotension in these patients, the feasibility of the test is comparable to that in individuals without hypertension.