Paolo M. Fioretti

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.

Enhanced sensitivity for detection of coronary artery disease by addition of atropine to dobutamine stress echocardiography

Patients undergoing dobutamine stress echocardiography often take beta antagonists which limit heart rate response and sensitivity in the test for detection of coronary artery disease. The aim of this study was to assess the effect of the addition of atropine to dobutamine stress echocardiography on clinical, electrocardiographic and echocardiographic outcomes. Dobutamine stress echocardiography was performed starting at and increasing every 3 minutes with 10 micrograms/kg/min to a maximum of 40 micrograms/kg/min (stage 4), which was continued for 6 minutes. In patients not achieving 85% predicted maximal exercise heart rate and in whom the test was not judged positive on echocardiographic or electrocardiographic criteria, atropine (0.25 mg intravenously, repeated up to a maximum of 1 mg if necessary) was added and dobutamine continued for up to a further 5 minutes, or until an adequate heart rate was achieved or the test was stopped because of chest pain or electrocardiographic changes. Of 80 consecutive patients undergoing dobutamine stress echocardiography within 2 weeks of coronary angiography, 49 required atropine (group A) and 31 required only dobutamine (group B). After dobutamine alone, heart rate (mean +/- SD) was higher in group B than in group A: 129 +/- 20 vs 90 +/- 18 beats/min, p less than 0.0001; but after the addition of atropine, heart rate in group A increased to 120 +/- 20 beats/min. Overall sensitivity for the detection of coronary disease was 70%, 95% confidence interval (CI) 55 to 83%; after the addition of atropine, sensitivity for group A was 65%, 95% CI 45 to 81%; in group B, sensitivity was 81%, 95% CI 54 to 96%.(ABSTRACT TRUNCATED AT 250 WORDS)

Prediction of Improvement of Regional Left Ventricular Function After Surgical Revascularization A Comparison of Low-Dose Dobutamine Echocardiography With 201Tl Single-Photon Emission Computed Tomography

BACKGROUNDnAlthough both 201Tl scintigraphy and low-dose dobutamine echocardiography (LDDE) have been proposed as effective methods of assessing myocardial viability, their relative efficacies are unknown. The aim of the present study was to compare the two imaging techniques in the prediction of improvement of regional left ventricular (LV) function after surgical revascularization.nnnMETHODS AND RESULTSnThirty-eight patients with severe chronic LV dysfunction (ejection fraction < or = 40%, one or more akinetic [Ak] or severely hypokinetic [SH] segments on resting echocardiogram) who underwent uncomplicated coronary artery bypass graft surgery were studied with simultaneous dobutamine stress echocardiography and poststress reinjection 201Tl single-photon emission computed tomography (SPECT) before surgery. The Ak or SH segments were considered viable by LDDE when wall thickening improved during the infusion of 10 micrograms.kg-1 min 1 dobutamine. Scintigraphic definition of viability was the presence of normal 201Tl uptake, totally reversible defect, partially reversible defect, or moderately severe fixed defect. The postoperative improvement of dyssynergic segments was determined with a rest echocardiogram 3 months after surgery. Of 608 LV segments, 169 were classified as Ak and 51 as SH on resting preoperative echocardiography. Of these, 170 were successfully revascularized. Wall motion during LDDE improved in 33 severely dyssynergic segments and was more frequent in SH than in Ak segments (19 of 44 versus 14 of 126, P < .0001). Viability was detected by 201Tl SPECT criteria in 103 SH or Ak segments. Thirty-two of the 33 segments from LDDE responders were judged viable on 201Tl SPECT, whereas 201Tl viability was also detected in 71 of 137 segments from LDDE nonresponders. The sensitivity and the specificity for the prediction of postoperative improvement of segmental wall motion were 74% (95% confidence interval [CI], 67% to 81%) and 95% (95% CI, 92% to 98%) by LDDE and 89% (95% CI, 84% to 94%) and 48% (95% 40% to 56%) by 201Tl SPECT, respectively. Positive predictive value of LDDE was higher than that of 201Tl SPECT (85%, [95% CI, 80% to 90%] versus 33% [95% CI, 26% to 40%]). Thirty-six patients had angina before and only 1 had angina 3 months after revascularization. High-dose dobutamine echocardiography demonstrated significant reduction in stress-induced ischemia (new or worsening of preexisting wall motion abnormalities) after surgery (from 163 to 23 LV segments).nnnCONCLUSIONSnIn patients with severe chronic LV dysfunction, LDDE is a good predictor of the improvement of dyssynergic segments after revascularization. Because 201Tl SPECT overestimates the probability of postoperative improvement of dyssynergic segments, LDDE should be the preferred imaging technique for preoperative assessment of these patients.

Dobutamine stress echocardiography for assessment of perioperative cardiac risk in patients undergoing major vascular surgery.

BackgroundThe purpose of this study was to determine the predictive value of dobutamine stress echocardiography for perioperative cardiac events in patients scheduled for elective major noncardiac vascular surgery. Methods and ResultsPatients (N = 136; mean age, 68 years) unable to exercise underwent a dobutamine stress test before surgery (incremental dobutamine infusion [10-40 μg. kg-1. min-1] continued with atropine [0.25-1 mg i.v.] if necessary to achieve 85% of the age-predicted maximal heart rate without symptoms or signs of ischemia). The clinical risk profile was evaluated by Detskys modification Goldmans risk factor analysis. Echocardiographic images were evaluated by two observers blinded to the clinical data of the patients, and results of the test were not used for clinical decision making. Technically adequate images were obtained in 134 of 136 patients, one major complication occurred (ventricular fibrillation), and three tests were discontinued prematurely because of side effects. Finally, data from 131 patients were analyzed with univariate and multivariate methods. The dobutamine stress test was positive (new or worsened wall motion abnormality) in 35 of 131 patients. In the postoperative period, five patients died of myocardial infarction, nine patients had unstable angina, and one patient developed pulmonary edema. All patients with cardiac complications (15 patients) had a positive dobutamine stress test. cardiac events occurred in patients with negative tests. Five patients with a technically inadequate prematurely stopped test were operated on without complications. By multivariate analysis (logistic regression), only age >70 years and new wall motion abnormalities during the dobutamine test were significant predictors of perioperative cardiac events. ConclusionsDobutamine stress echocardiography is a feasible, safe, and useful method for identifying patients at high or low risk of perioperative cardiac events. The test yields additional information, beyond that provided by clinical variables, in patients who are scheduled for major noncardiac vascular surgery.

Improved cardiac risk stratification in major vascular surgery with dobutamine-atropine stress echocardiography

OBJECTIVESnThis study sought to optimize preoperative cardiac risk stratification in a large group of consecutive candidates for vascular surgery by combining clinical risk assessment and semiquantitative dobutamine-atropine stress echocardiography.nnnBACKGROUNDnDobutamine-atropine stress echocardiography has been used for the prediction of perioperative cardiac risk in a small group of patients scheduled for elective major vascular surgery on the basis of the presence or absence of stress-induced regional left ventricular wall motion abnormalities.nnnMETHODSnClinical risk assessment and dobutamine-atropine stress echocardiography were performed in 302 consecutive patients presenting for major vascular surgery. The extent and severity of stress wall motion abnormalities and the heart rate at which they occurred, in addition to the presence of wall motion abnormalities at rest, were assessed.nnnRESULTSnThe absence of clinical risk factors (angina, diabetes, Q waves on the electrocardiogram, symptomatic ventricular tachyarrhythmias, age > 70 years) identified a low risk group of 100 patients with a 1% cardiac event rate (unstable angina). Dobutamine-atropine stress echocardiographic findings were positive in 72 patients. Twenty-seven patients had a perioperative cardiac event (cardiac death in 5, nonfatal infarction in 12, unstable angina pectoris in 10); all 27 patients had positive stress test results (positive predictive value 38%, negative predictive value 100%). The semiquantitative assessment of the extent and severity of ischemia did not provide additional prognostic information in patients with positive test results. In contrast, the heart rate at which ischemia occurred defined a high risk group with a low ischemic threshold (38 patients with 20 events [53%]) and an intermediate risk group with a high ischemic threshold (34 patients with 7 events [21%]). All 5 patients with a fatal outcome and 8 of 12 with a nonfatal myocardial infarction were in the high risk group with a low ischemic threshold.nnnCONCLUSIONSnClinical variables identify 33% of patients at very low risk for perioperative complications of vascular surgery in whom further testing is redundant. In all other candidates, dobutamine-atropine stress echocardiography is a powerful tool that identifies those patients at intermediate risk and a small group at very high risk. Risk stratification with a combination of clinical assessment and pharmacologic stress echocardiography has the potential to facilitate clinical decision making and conserve resources.

Long-term prognostic value of dobutamine-atropine stress echocardiography in 1737 patients with known or suspected coronary artery disease : A single-center experience

BACKGROUNDnThe purpose of this study was to assess the long-term value of dobutamine-atropine stress echocardiography (DSE) for prediction of late cardiac events in patients with proven or suspected coronary artery disease.nnnMETHODS AND RESULTSnClinical data and DSE results were analyzed in 1734 consecutive patients undergoing DSE between 1989 and 1997. Seventy-four patients who underwent revascularization within 3 months of DSE and 1 patient lost to follow-up were excluded; the remaining 1659 (median age, 62 years; range, 14 to 99 years) were followed up for 36 months (range, 6 to 96 months). Wall motion abnormalities at rest and the presence and extent of stress-induced wall motion abnormalities (ischemia) were scored for each patient. Cardiac events were related to clinical and ECG data and DSE results. Four hundred twenty-eight cardiac events occurred in 366, documented cardiac death in 108 (total death, 247), nonfatal infarction in 128, and late revascularization in 192 patients. In a multivariable Cox proportional-hazards model, the ratio of documented cardiac death or (re)infarction was increased in the presence of stress-induced ischemia (hazard ratio, 3.3; 95% CI, 2.4 to 4.4) and extensive rest wall motion abnormalities (hazard ratio, 1.9; 95% CI, 1.3 to 2.6). The number of ischemic segments was predictive for late cardiac events. A normal DSE carried a relatively good prognosis, with an annual event rate of cardiac death or infarction of 1.3% over a 5-year period.nnnCONCLUSIONSnIn a large group of patients, DSE has an added value for predicting late cardiac events during long-term follow-up, improving the separation between high- risk and very-low-risk patients.

Simultaneous dobutamine stress echocardiography and technetium-99m isonitrile single-photon emission computed tomography in patients with suspected coronary artery disease

OBJECTIVESnThe purpose of this study was to determine the relative value of dobutamine stress echocardiography and technetium-99m isonitrile single-photon emission computed tomography (mibi SPECT) in the detection of myocardial ischemia.nnnBACKGROUNDnStress-induced new wall motion abnormalities and transient perfusion defects are both used for the diagnosis of myocardial ischemia.nnnMETHODSnOne hundred five consecutive patients with either proved or suspected coronary artery disease, who were referred for perfusion scintigraphy, were studied by a combination of the two techniques. Both echocardiographic and mibi SPECT images were visually analyzed. Three patients were excluded from the final analysis because of unsatisfactory examinations: two with noninterpretable stress echocardiograms and one with noninterpretable mibi SPECT images. The response to stress was concordantly classified by both techniques in 68% of patients (kappa = 0.51).nnnRESULTSnDobutamine stress echocardiography revealed the presence of ischemia in 38 and mibi SPECT in 45 patients (overall agreement = 74%, kappa = 0.46). The agreement was higher in patients without previous myocardial infarction (84%, kappa = 0.62). When regional analysis was performed, concordance of stress echocardiography and mibi SPECT occurred in 84% of the 306 regions (kappa = 0.45). Regional agreement was also slightly higher in patients without previous infarction (88%, kappa = 0.50). In 21 patients without previous myocardial infarction who underwent coronary angiography, the overall sensitivity of dobutamine stress echocardiography and mibi SPECT for the diagnosis of coronary artery disease (diameter stenosis > 50%) was 75% and 83%, respectively, with a specificity of 89% (eight of nine patients) for both tests.nnnCONCLUSIONSnDobutamine stress echocardiography represents a reasonable alternative to dobutamine mibi SPECT for the functional assessment of patients with suspected myocardial ischemia and without previous myocardial infarction.

Is transluminal coronary angioplasty mandatory after successful thrombolysis? Quantitative coronary angiographic study.

Percutaneous transluminal coronary angioplasty has been advocated as a mandatory procedure to prevent reocclusion after successful thrombolysis in acute myocardial infarction. This study describes our experience with both procedures over a 12 month period. Out of 105 patients catheterised in the acute phase of myocardial infarction, 64 were recanalised with 250 000 units of streptokinase, while in 25 patients recanalisation could not be achieved. In the remaining 16, the infarct related vessel was patent at the time of the procedure. Eighteen of the 78 patients who had a patent infarct related vessel at the end of the recanalisation procedure underwent transluminal angioplasty immediately afterwards. Post lysis angiograms were analysed quantitatively with a computerised measurement system. The contours of the relevant arterial segments were detected automatically. Reference diameter, minimal obstruction diameter, length of the lesions, and percentage diameter stenosis were averaged from multiple views. In 31% of our patients a diameter stenosis of less than 5O0/o was found whereas one of 70% or more was seen in only 19%. Eleven stenotic lesions, recanalised at the acute stage, reoccluded in the short term, and in the long term eight other patients sustained a reinfarction in the same myocardial territory. Seventeen of these 19 recanalised lesions had a diameter stenosis of 580/o or more. In view of these results, we felt justified in combining recanalisation and angioplasty in 18 patients selected from the most recent admissions. In these patients, the mean diameter stenosis decreased from 590/o to 30% and mean pressure gradient from 41 to 8 mmHg. Late follow up showed reocclusion in one

Exercise echocardiography and technetium-99m MIBI single-photon emission computed tomography in the detection of coronary artery disease

To compare the relative diagnostic value of exercise echocardiography with perfusion technetium-99m metoxyisobutylisonitrile single-photon emission computed tomography (SPECT) in detecting coronary artery disease (CAD), 75 patients with suspected CAD but a normal electrocardiogram (ECG) at rest were included in a prospective correlative study. Both the exercise echocardiograms and SPECT studies were performed in conjunction with the same symptom-limited bicycle exercise test. The development of either a new wall motion abnormality or a reversible perfusion defect after exercise, or both, were regarded as a positive test for the exercise echocardiographic and SPECT studies, respectively. The results of these 2 diagnostic tests were compared with coronary arteriography. Exercise echocardiography identified 35 (71%) and SPECT 41 (84%, p = 0.13) of the 49 patients with significant CAD (defined as greater than 50% diameter stenosis). Twenty-five of the 26 patients (96%) without significant coronary stenosis had negative exercise echocardiographic results and 23 of 26 (88%) had negative SPECT results. Exercise-induced new wall motion abnormalities showed a good correlation with reversible perfusion defects, and the results of the 2 methods were concordant in 65 of 75 patients (agreement = 88%, kappa = 0.75 +/- 0.14). Both the diagnostic accuracy of exercise echocardiography and SPECT were significantly higher than the exercise ECG (81 vs 64%, p less than 0.02 and 88 vs 64%, p less than 0.005). The sensitivity and specificity for detecting individual diseased vessels were 60 and 95% for exercise echocardiography and 67 and 94% for SPECT.(ABSTRACT TRUNCATED AT 250 WORDS)

Accurate Measurement of Left Ventricular Ejection Fraction by Three-dimensional Echocardiography A Comparison With Radionuclide Angiography

BACKGROUNDnThree-dimensional echocardiography is a promising technique for calculation of left ventricular ejection fraction, because it allows its measurement without geometric assumptions. However, few data exist that study its reproducibility and accuracy in patients.nnnMETHODS AND RESULTSnTwenty-five patients underwent radionuclide angiography and three-dimensional echocardiography that used the rotational technique (2 degrees interval and ECG and respiratory gating). Left ventricular volume and ejection fraction were calculated by use of Simpsons rule at a slice thickness of 3 mm. Analyses were performed to define the largest slice thickness required for accurate calculation of left ventricular volume and ejection fraction. Three-dimensional echocardiography showed excellent correlation with radionuclide angiography for calculation of left ventricular ejection fraction (mean +/- SD, 38.9 +/- 19.8 and 38.5 +/- 18.0, respectively; r = .99); their mean difference was not significant (0.03 +/- 0.17; P = .3), and they had a close limit of agreement (-0.385, 0.315). Intraobserver variability for radionuclide angiography and three-dimensional echocardiography was 4.2% and 2.6%, respectively, whereas interobserver variability was 6.2% and 5.3%, respectively. There was no significant difference between left ventricular volume and ejection fraction calculated at a slice thickness of 3 mm and that calculated at different slice thicknesses up to 24 mm. However, the standard deviation of the mean difference showed a stepwise increase, particularly at thicknesses > 15 mm. At a slice thickness of 15 mm, the probability of three-dimensional echocardiography to detect > or = 6% difference in ejection fraction was 80%.nnnCONCLUSIONSnThree-dimensional echocardiography has excellent correlation with radionuclide angiography for calculation of left ventricular ejection fraction in patients and has an observer variability similar to that of radionuclide angiography. We recommend the use of a 15-mm-thick slice for accurate and rapid measurement of left ventricular volume and ejection fraction.