Clinical and physiologic evidence indicates that maximal coronary vasodilation is not achieved in a large number of patients with use of the standard dose of dipyridamole (0.56 mg/kg body weight over ...4 min). The feasibility, safety and accuracy of technetium-99m hexakis 2-methoxy-2-isobutyl isonitrile (Sestamibi) scintigraphy associated with intravenous high dose dipyridamole (0.56 mg/kg over 4 min followed 4 min later by an additional 0.28 mg/kg over 2 min) were evaluated in a multicenter study. Planar myocardial perfusion images were obtained at rest and after dipyridamole in 101 patients with effort chest pain and no prior myocardial infarction. High dose dipyridamole (62 patients) was used when typical chest pain or electrocardiographic (ECG) signs of ischemia, or both, did not occur during or after the standard dose (39 patients). With high dose dipyridamole, 34 patients had pain (18 patients) or ECG signs of ischemia (ST depression ≥2 mm) (8 patients), or both (8 patients), whereas the other 28 patients had Sestamibi injection in the absence of symptoms or ECG changes.
All patients underwent coronary angiography: 81 had significant coronary artery disease (≥50% reduction of lumen diameter) (affecting one vessel in 38, two vessels in 19 and three vessels in 24 patients) and 20 patients had normal coronary arteries. The overall sensitivity, specificity and predictive accuracy of Sestamibi scintigraphy were 81%, 90% and 83%, respectively. No significant hypotension, ventricular arrhythmias or other serious adverse reactions occurred in any of the patients tested with the high dose dipyridamole; minor side effects occurred in 52% and 57% of patients at standard and high dose dipyridamole, respectively, and were well tolerated in all.
In conclusion, Sestamibi scintigraphy associated with high dose dipyridamole is an accurate method of evaluating suspected ischemic heart disease in patients; it did not result in an increased number of side effects as compared with those associated with the standard dose protocol.
Our aim was to verify whether the sensitivity of pharmachological stress echocardiography for multivessel disease after acute myocardial infarction may be improved by a more aggressive protocol, i.e. ...not considering the appearance of the first wall motion abnormality as the absolute end-point if it occurs in the infarcted area without clinical or instrumental markers of extensive ischemia or left ventricular dysfunction. One-hundred twenty-one consecutive patients (age 32–71 years) prospectively underwent dobutamine-atropine stress echo (dobutamine infusion up to 40 μg/kg/min with additional atropine 1 mg) 11.8 ± 4.8 days after uncomplicated myocardial infarction and coronary angiography within 6 weeks. Criteria for stopping the test were: significant ST depression or elevation, typical chest pain, major arrhythmias and left ventricular dysfunction. The test was considered as positive if a deterioration of basal wall motion pattern was observed: it was defined homozonally positive (the deterioration occurred in the myocardial area fed by the culprit vessel) or heterozonally positive (the deterioration occurred in a different vascular area). A coronary stenosis >70% of vessel lumen was defined as critical. Thirty-four patients showed a negative test result. Among the 87 patients with positive test, 65 had no further wall motion deterioration from the first-induced wall motion abnormality (WMA) to peak test (Group A), whereas nine patients showed further homozonal (Group B) and 13 further heterozonal (Group C) asynergies. Sensitivity, specificity and accuracy of dobutamine stress echocardiography for multivessel disease were, respectively, 63%, 96% and 82% using the first-induced wall motion abnormality as test end-point, whilst they were 84% (
P < 0.01), 93% and 89% according to the aggressive approach previously described. Dobutamine stress time of patients with multivessel disease was higher in Groups B and C (13.1 ± 3.6 min) than in Group A (9.8 ± 3.7 min,
P < 0.01) and, finally, the mean obstruction of non-culprit vessel was higher in Group A (62.2%) than in Group C (47.4%,
P < 0.05). No major complications were found. We conclude that the sensitivity of dobutamine stress echocardiography for multivessel disease following recent myocardial infarction is critically dependent on the test end-point. It may be improved by a more aggressive approach capable to identify less severe heterozonal coronary lesions.
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