Brief reportIschemic ST-segment changes after dipyridamole infusion
Abstract
Thirty consecutive patients were studied by thallium-201 myocardial imaging after dipyridamole infusion and by coronary angiography because of syndromes of chest pain. Eight patients (27%) had ischemic ST-segment changes after the infusion of dipyridamole. They all had significant coronary arterial disease. It is suggested that the combination of visual analysis of myocardial imaging and analysis of ST-segment changes be used after dipyridamole infusion to improve the sensitivity of this non-invasive test.
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Cited by (12)
QRS score versus ST-segment changes in patients undergoing Tl-201 scintigraphy using dipyridamole infusion
2005, Journal of Nuclear CardiologyST-segment changes after dipyridamole infusion followed by handgrip isometric stress lack diagnostic value, because of the low sensitivity for the detection of coronary artery disease (CAD). In addition, an abnormal QRS score during exercise had a greater diagnostic ability than ST-segment changes to detect CAD. This study was undertaken to compare QRS score values with ST-segment changes during thallium 201 scintigraphy via dipyridamole infusion.
In this study 128 patients (101 men and 27 women), aged 53 to 72 years (mean, 59 ± 8 years), underwent Tl-201 scintigraphy after dipyridamole infusion and handgrip isometric stress, as well as coronary angiography. QRS score values and ST-segment changes after dipyridamole infusion and handgrip isometric stress were also estimated. CAD was detected in 96 patients (75%), whereas normal coronary arteries were found in 32 (25%). According to scintigraphic data, 48 patients (37%) had no reversible perfusion defects whereas 80 (63%) had at least 1 reversible perfusion defect. Sensitivities for an abnormal QRS score and ST-segment deviation were 68% versus 18% (P < .01) for detection of CAD and 75% versus 19% for detection of myocardial ischemia (P < .01), respectively. Similar specificities were found (P = not significant).
An abnormal QRS score significantly improves the low sensitivity of ST-segment changes for the detection of myocardial ischemia and CAD by use of Tl-201 scintigraphy with dipyridamole infusion and handgrip isometric stress.
Safety of dipyridamole testing in 73,806 patients: The Multicenter Dipyridamole Safety Study
1995, Journal of Nuclear CardiologyBackground Dipyridamole imaging is widely used as an alternative to exercise testing to identify and risk stratify patients with coronary artery disease. Safety data on intravenous dipyridamole stress testing has been derived largely from individual institutional data.
Methods and Results Data were collected retrospectively by 85 coinvestigators from 73,806 patients who underwent intravenous dipyridamole stress imaging in 59 hospitals and 19 countries to determine the incidence of major adverse reactions during testing. The dose of dipyridamole infused was 0.56 mg/kg in 64,740 patients, 0.74 mg/kg in 6551 patients, and 0.84 mg/kg in 2515 patients. Combined major adverse events among the entire 73,806 patients included seven cardiac deaths (0.95 per 10,000), 13 nonfatal myocardial infarctions (1.76 per 10,000), six nonfatal sustained ventricular arrhythmias (0.81 per 10,000) (ventricular tachycardia in two and ventricular fibrillation in four), nine transient cerebral ischemic attacks (1.22 per 10,000), (with speech or motor deficit), one stroke, and nine severe bronchospasms (1.22 per 10,000) (one intubation and eight near intubations). In addition to the safety data, detailed demographic, peripheral hemodynamic, side effect, and concomitant drug data were examined in a subgroup of 3751 patients. End points from subsets of patients were compared with those of the group as a whole. Multivariate analysis revealed that dipyridamole-induced chest pain was more common in patients less than 70 years old (p=0.0017), those with a history of coronary revascularization (p=0.002), or patients taking aspirin (p=0.0001). Minor noncardiac side effects were less frequent among the elderly (p=0.0053) and more frequent in women (p=0.0001) and patients taking maintenance aspirin (p=0.0034). When a patient was judged on the basis of the adequacy of hemodynamic response to be a dipyridamole “nonresponder” (<10 mm Hg drop in systolic blood pressure and 10 beats/min increase in heart rate), the only significant predictor was angiotensin-converting enzyme inhibitor intake (p=0.0025). Inferoposterior hypoperfusion was significantly more frequent in patients with dipyridamole-induced hypotension: 57% (44/77) (p<0.0001) of those who had hypotension and 89% (8/9) (p=0.0076) who had severe symptomatic bradyarrhythmias displayed inferoposterior defects on thallium scanning. Caffeine levels were determined in 391 consecutive patients: levels greater than 5 mg/L were observed in only eight patients (2%), suggesting that methylxanthine levels sufficient to alter the hemodynamic response to dipyridamole resulting in suboptimal hyperemic stress are unlikely when patients take nothing by mouth after midnight.
Conclusion The risk of serious dipyridamole-induced side effects is very low and is comparable to that reported for exercise testing in a similar patient population.
ST-segment depression during adenosine infusion as a predictor of myocardial ischemia
1994, American Heart JournalThe incidence and hemodynamic changes associated with ST-segment depression during adenosine stress testing are poorly defined. To examine this, 550 consecutive patients who underwent adenosine perfusion testing were evaluated for the development of ST-segment depression. At least 1 mm of horizontal or downsloping depression developed in 82 patients (15.9%) and was observed with similar frequency in patients with normal scans and those with only fixed defects. ST depression developed in 58 of 242 patients with reversible defects (sensitivity = 24%) and in only 24 of 275 patients without reversible defects (specificity = 91%). Its presence was highly predictive of reversible perfusion defects (predictive accuracy = 71%). Similar findings were observed in patients with and without ECG evidence of left ventricular hypertrophy. Patients with ST depression had perfusion defects in more vessel distributions, had more severe defects, and had a greater increase in heart rate during adenosine infusion. Thus ST-segment depression occurs infrequently during adenosine infusion but is specific for and predictive of myocardial ischemia, as evidenced by reversible perfusion scan defects. Patients with ST depression have more severe disease and develop faster heart rates during infusion, which could result in decreased coronary perfusion during diastole allowing for the development of myocardial ischemia.
State-of-the-art myocardial perfusion imaging
1994, Cardiology ClinicsMyocardial perfusion scintigraphy has advanced significantly since its introduction approximately two decades ago. Recently, Tc-99m-labeled agents have become clinically available that offer improved imaging characteristics in comparison with the conventional Tl-201. The method of image analysis has also advanced from qualitative interpretation to objective quantitative analysis. Furthermore, parallel with these developments, myocardial perfusion scintigraphy with positron emission tomography (PET) has matured to a clinical tool. This article primarily reviews the clinical applications of single photon myocardial perfusion scintigraphy for the detection, localization, and identification of extensive coronary disease
ST-segment depression during dipyridamole infusion, and its clinical, scintigraphic and hemodynamic correlates
1992, The American Journal of CardiologyThe goal of this study was to determine whether dipyridamole-induced ST-segment depression reflects more severe or extensive myocardial hypoperfusion than the absence of this electrocardiographic finding. The clinical, hemodynamic and scintigraphic correlates of ST-segment depression during intravenous dipyridamole infusion were studied in 204 consecutive patients undergoing dipyridamole stress thallium-201 (Tl-201) imaging for evaluation of coronary artery disease. Of 182 patients with a diagnostic baseline electrocardiogram, 28 (15%) developed ST depression after dipyridamole. Patients with ST depression, compared with those without, were older (64 ± 1 vs 60 ± 1 years; p < 0.03) and had a higher frequency of chest pain (57 vs 23%; p < 0.001) and a higher heart rate-blood pressure product (12.7 ± 0.6 vs 11.2 ± 0.2 × 103; p < 0.008) after dipyridamole. Patients with ST depression were more likely to have Tl-201 redistribution (64 vs 38%; p < 0.02) and a greater number of redistribution defects (2.3 ± 0.04 vs 0.9 ± 0.1, p < 0.001) than were those without ST depression.
By multivariate logistic regression analysis, the most powerful correlate of ST depression was the number of segments having Tl-201 redistribution (p < 0.001). Other independent correlates were presence of chest pain, heart rate at Tl-201 injection, and age. Thus, the determinants of dipyridamole-induced ST-segment depression include the scintigraphic extent of reversible hypoperfusion, as well as indexes of myocardial oxygen demand.
Dipyridamole perfusion scintigraphy
1991, Seminars in Nuclear MedicineDipyridamole is one of several agents that may be infused intravenously to noninvasively evaluate coronary perfusion without dynamic exercise. Among such agents it is the most investigated, and it is associated with the greatest clinical experience. Its mechanism of action utilizes intrinsic adenosine and does not require the induction of ischemia. Rather, the method tests the coronary flow reserve by dilating the precapillary and arteriolar capillary beds. Vessels with a limited coronary flow reserve demonstrate reduced responsiveness with relative flow reduction and a resultant defect on perfusion scintigraphy. Side effects are common and generally benign, but deaths have been reported and they generally relate to severe hypotension, prolonged dense ischemia and resultant infarction, or bronchospasm. Severe complications are rare and can be avoided by the prompt administration of aminophylline, the dipyridample antedote. Diagnostic accuracy for the identification of coronary disease appears similar to that for exercise perfusion scintigraphy. It should be applied to patients with known or suspected coronary disease who require coronary evaluation, but who cannot exercise adequately for diagnostic or prognostic purposes. In such patients, the method is useful for the preoperative assessment of risk at peripheral vascular and other major noncardiac surgery. It may be of value as well in the assessment of the otherwise uncomplicated patient postinfarction. Not yet established is its application to the patient with unstable angina or in the acute setting, after coronary reperfusion. Similarly, its comparison with direct adenosine infusion or with pharmacological agents whose mechanism rests entirely on ischemia induction, as does dobutamine, has until now been limited. Unlike its use with perfusion scintigraphy, the application of dipyridamole with echocardiography and other functional ischemic indicators is totally dependent on the induction of ischemia. This is likely less frequent than the induction of nonischemic perfusion heterogeneity. The agent is now commonly available and will make a significant beneficial impact on patient evaluation and management.