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PubMed1998

Low-dose and high-dose acetylsalicylic acid, with and without dipyridamole: a review of clinical trial results.

Publication of the results of the second European Stroke Prevention Study (ESPS-2) provided the incentive for an update of the meta-analyses of aspirin and dipyridamole in the secondary prevention of stroke. After review of published randomized trials of prolonged treatment with aspirin, dipyridamole, or their combination in patients with a history of stroke or transient ischemic attack (TIA), data on the occurrence of stroke, myocardial infarction, and vascular death were used to calculate overall relative risk reductions. The relative risk reduction for aspirin versus placebo was 13%. The same relative risk reduction was found in separate meta-analyses of trials with high (1,000-1,500 mg), medium (250-500 mg), and low (50-100 mg) doses of aspirin. Trials in which different doses were compared showed no difference in the occurrence of vascular events. The addition of dipyridamole to low-dose aspirin further reduced the risk for vascular events by 15%. We conclude from current trials that low-dose aspirin alone reduced the risk of vascular events in patients with prior stroke or TIA by 13%. There is no evidence of a dose-effect relationship. An additional reduction of the risk by 15% can be obtained by adding dipyridamole to aspirin. The overall evidence for the relative effects of the combination of dipyridamole and aspirin versus aspirin alone or placebo is highly consistent. The clinical evidence now favors the two agents in combination over aspirin alone.

Aspirin↗
PubMed2005

Portable type signal-averaged electrocardiography with dipyridamole: a new and convenient method to detect patients with coronary artery disease and ischemia.

BACKGROUND: Whether or not patients with coronary artery disease (CAD) could be easily detected at the bedside using dipyridamole stress was investigated using a portable type signal-averaged electrocardiography (portable SAECG). METHODS AND RESULTS: The standard 12-lead QRS wave SAECG was performed at the bedside before and after dipyridamole stress in 30 patients with angiographically significant stenotic lesions, who had positive myocardial ischemia in the dipyridamole-thallium myocardial perfusion imaging (CAD group), and 33 patients with no significant stenotic lesions, who had negative imaging (control group). The filtered QRS duration (fQRSd) before and after dipyridamole stress was determined by the vector magnitude method and the difference (DeltafQRSd) was obtained. Furthermore, the DeltafQRSd was obtained using the multiphasic oscillation method, as well at the same standard 12-lead, and the maximal value of changes in fQRSd (MAX DeltafQRSd) between the 12 leads was determined. The DeltafQRSd was similar between 2 groups (p = 0.11). The MAX DeltafQRSd associated was significantly greater in the CAD group (p < 0.0001). When a cut-off value of MAX DeltafQRSd > or = 5 ms was used for the detection of CAD, the sensitivity and specificity were 97 and 94%, respectively. CONCLUSION: The portable dipyridamole-stress SAECG easily detect CAD and myocardial ischemia at the bedside.

Aged↗
PubMed1993

Ratio of lung to heart thallium-201 uptake on exercise and dipyridamole stress imaging in coronary artery disease--implication of SPECT.

To examine whether measurements of lung thallium-201 (Tl-201) uptake with single photon emission computed tomography (SPECT) following exercise or dipyridamole infusion provide complementary information as reported in planar imaging, we examined 140 patients undergoing exercise or dipyridamole Tl-201 SPECT and coronary arteriography for the diagnosis of coronary artery disease (CAD). On the reconstructed coronal tomographic image, regions of interest were placed over the left upper lung field and the left ventricular myocardium. Lung to heart ratio (L/H ratio) was calculated as a fraction of average Tl-201 counts per pixel in the lung divided by those in the myocardium. An L/H ratio of larger than a value of mean +2 standard deviation, derived from patients without significant coronary stenosis, was considered as abnormal. The patients with abnormal L/H ratio on exercise Tl-201 SPECT had larger extent and severity scores of Tl-201 defects on the initial image, lower left ventricular ejection fraction, higher end-diastolic pressure and higher incidence of multi-vessel CAD than those with the normal ratio. However, in dipyridamole studies, abnormal L/H ratio did not relate to scintigraphic or hemodynamic severity. These data confirmed that increased lung Tl-201 uptake after exercise suggested the presence of extensive CAD or left ventricular dysfunction. However, L/H ratio might be less useful in dipyridamole studies. Thus, quantitative measurements of L/H ratio with exercise but not dipyridamole SPECT could provide additional information related to the involved cardiac pump performance in CAD.

Adult↗
PubMed1995

Assessment of the severity of coronary artery disease by thallium-201 washout rate after dipyridamole infusion--a coronary hemodynamic and metabolic study.

This study examined the relationship between the myocardial washout rate (WR) of thallium-201 (201Tl) in dipyridamole scintigraphy and both coronary flow reserve (CFR) and myocardial lactate extraction rate (LER) after dipyridamole infusion in 31 patients with coronary artery disease (CAD) without myocardial infarction and 16 control patients. Patients with CAD demonstrated significantly lower WR (21 +/- 17 vs 43 +/- 10%, p < 0.001), lower CFR (128 +/- 82 vs 242 +/- 89%, p < 0.001) and lower LER (-2 +/- 20 vs 10 +/- 10%, p < 0.05) than did the control patients. WR was significantly correlated with CFR (r = 0.50, p < 0.001) and LER (r = 0.41, p < 0.01) in all of the patients. CAD patients with dipyridamole-induced chest pain demonstrated significantly lower WR (14 +/- 20 vs 27 +/- 12%, p < 0.05), lower CFR (97 +/- 71 vs 162 +/- 82%, p < 0.05) and lower LER (-13 +/- 21 vs 11 +/- 9%, p < 0.001) than did CAD patients without chest pain. CAD patients with dipyridamole-induced ST depression demonstrated significantly lower WR (14 +/- 20 vs 29 +/- 8%, p < 0.05), lower CFR (105 +/- 79 vs 170 +/- 73%, p < 0.05) and lower LER (-8 +/- 21 vs 11 +/- 10%, p < 0.01) than did CAD patients without ST depression. These results suggest that the myocardial washout rate of 201Tl after dipyridamole infusion reflects the severity of coronary artery disease as assessed by coronary hemodynamics, myocardial metabolism, symptoms and electrocardiography.

Aged↗
PubMed1989

Transmitral flow changes during dipyridamole-induced ischemia. A Doppler-echocardiographic study.

Myocardial ischemia results in altered left ventricular (LV) diastolic compliance, reflected by an abnormal mitral inflow pattern on Doppler echocardiography. To investigate the relationship of Doppler echocardiography and regional myocardial systolic function during dipyridamole infusion, we evaluated transmitral flow changes detected by pulsed Doppler technique during a high-dose dipyridamole echocardiography test (DET, two-dimensional echo monitoring with dipyridamole infusion, up to 0.84 mg/kg over 10 min). The DET response produced two groups: group 1 (34 patients) with negative DET, and group 2 (35 patients) with positive DET, defined as the development of a newly onset LV regional asynergy. The E/A values overlapped at baseline (1.07 +/- .32 vs .92 +/- .22; p = NS) but differed at peak changes (.92 +/- .26 vs. 75 +/- .25; p less than .01). Heart rate changes could not account for the observed Doppler changes, since the values of R-R interval were similar in the groups, both basally (.927 +/- .226 vs .867 +/- .143 s; p = NS) and at peak dipyridamole (.754 +/- .100 vs. 681 +/- .112; p = NS). Transient myocardial ischemia induced by dipyridamole administration is accompanied by changes in transmitral flow, which consist of an increase in the relative atrial contribution to LV filling, possibly owing to an acute impairment in LV relaxation.

Adult↗
PubMed1993

Safety and accuracy of dipyridamole thallium myocardial scintigraphy in elderly patients.

This study examined mainly the adverse effects of 201Tl myocardial scintigraphy with dipyridamole (D-Tl) in 73 elderly patients over 70 years old in comparison with those in 65 younger patients. Fifty-five of 73 elderly patients (75%) and 49 of 65 younger patients (75%) had a persistent or dipyridamole-induced perfusion defect on D-Tl. The hemodynamic changes induced by dipyridamole as well as the incidence of cardiac and noncardiac adverse effects were similar in both groups and no serious adverse effect occurred in either group. Secondly, we examined the procedure's usefulness for detecting ischemic heart disease in elderly and younger patients. Dipyridamole induced perfusion defect was noted in 21 elderly patients and in 24 younger patients (N.S.). Among the patients in whom coronary angiography was performed, significant coronary artery stenosis was found in 5 of 8 elderly patients and 17 of 20 young patients (N.S.). In patients with one or two-vessel disease, the area with dipyridamole induced ischemia was concordant with the stenotic area seen on coronary angiography in 3 of 3 elderly patients and 12 of 13 younger patients (N.S.). Thus, the safety and usefulness of D-Tl for detecting myocardial ischemia were comparable in elderly and young patients.

Age Factors↗
PubMed1998

Dipyridamole decreases renal phosphate leak and augments serum phosphorus in patients with low renal phosphate threshold.

It has been shown that an acute infusion of dipyridamole increased renal phosphate reabsorption in rats and humans. A prospective study was performed to determine whether chronic treatment by dipyridamole given orally could decrease renal phosphate leak and increase serum phosphorus in patients with idiopathic low renal phosphate threshold (TmPO4/GFR < 0.77 mM). Sixty-four patients with low TmPO4/GFR were included and treated with dipyridamole (75 mg, 4 times daily) for more than 12 mo. Serum phosphorus, TmPO4/GFR, parathyroid hormone, serum calcium, and 1,25-dihydroxyvitamin D were measured sequentially before treatment, and after 3, 6 to 9, and 12 mo of treatment. Under chronic treatment with dipyridamole, TmPO4/GFR and serum phosphorus significantly increased in 80% of patients within 3 mo, with maximal values reached within 9 mo. This improvement persisted after 12 mo of treatment. In 28 patients, 1,25-dihydroxyvitamin D concentrations were above the normal range (> 42 pg/ml) and normalized in parallel with the increase of serum phosphorus. The 24-h calcium excretion (which was initially increased in patients with high vitamin D concentrations) and urolithiasis decreased under treatment. Ionized serum calcium and parathyroid hormone remained unchanged. After 2 yr, treatment was discontinued in three patients; serum phosphorus and TmPO4/GFR decreased within 1 mo after discontinuation. Dipyridamole at a dose of 75 mg 4 times daily increases low TmPO4/GFR and improves hypophosphatemia in patients with renal phosphate losses and can be used to treat these patients.

Administration, Oral↗
PubMed1979

Suppressive effect of dipyridamole on the proteinuria of aminonucleoside nephrosis in rat.

The suppressive effect of dipyridamole on the proteinuria of aminonucleoside nephrosis and protamine-induced proteinuria, was investigated. Male Wistar rats were given puromycin aminonucleoside (80 mg/kg s.c.) or protamine sulfate (20 mg/kg i.v.), and the urine was collected in metabolic cages. The content of proteins in the urine was determined by using a continuous gradient microgel electrophoresis procedure. Dipyridamole (20 mg/kg p.o.) suppressed the excretion of albumin and proteins larger than albumin (HMP) in aminonucleoside nephrosis. But the excertion of proteins smaller than albumin (LMP) was not affected by dipyridamole. Dipyridamole also suppressed the excertion of HMP in protamine-induced proteinuria, though the excretion of albumin and LMP was not affected. Puromycin aminonucleoside and protamine sulfate were known to cause renal glomerular epithelial changes referred to as "fusion" of foot processes. Since dipyridamole was effective in suppressing the both types of proteinuria, this drug was considered to improve the damaged renal glomerular barrier for plasma proteins.

Albuminuria↗
PubMedDate not supplied

[Intravenous dipyridamole in acute cerebral infarct. Is it efficacious?].

OBJECTIVE: To evaluate the efficiency of intravenous dipyridamole in the evolution of patients with acute ischemic stroke. METHODS: A double-blind clinical trial was conducted with 60 patients having a 24-h evolution of acute vascular stroke at the Hospital General No. 1 IMSS in the city of Colima, Mexico. After diagnosis, the patients were randomly assigned to two study groups. 10 mg of dipyridamole were administered intravenously every 8 h to the patients in one group, and 300 mg of aspirin were administered orally every 24 h to patients in the other. The patients in both groups received 25 to 50 ml/ kg of saline solution over a 24-h period. Basal conditions were registered using five parameters (food intake, walking, eye opening, motor activity and verbal responsiveness) during the first 5 days of evolution. RESULTS: Six patients died, four from the group treated with dipyridamole and two treated with aspirin. There was no significant difference between the groups in reference to age (66 +/- 11 years) or sex, nor was there a difference in the severity of stroke between the groups. When the values of the parameters recorded for both groups were compared before and after treatment, the group receiving dipyridamole showed no significant change (p < 2), while the group receiving aspirin showed an improvement in three of the parameters (food intake, walking and motor activity (p < 0.003). CONCLUSION: Our results indicate that dipyridamole does not modify basal conditions in patients suffering from acute ischemic stroke, while aspirin mildly favors improvement in these patients. We conclude that appropriate medical care, in the absence of complications, is the underlying condition permitting a satisfactory evolution in patients afflicted with brain vascular disease.

Acute Disease↗
PubMed2000

Persistent myocardial ischemia after termination of dipyridamole-induced ventricular tachycardia by intravenous aminophylline: scintigraphic demonstration.

Ventricular tachycardia is a rare complication of dipyridamole stress testing. We present a case in which dipyridamole induced symptomatic ventricular tachycardia. The patient, a 41-year-old man with a history of chest discomfort on exertion for 1 year, underwent dipyridamole thallium imaging. Sustained ventricular tachycardia occurred 1 minute and 40 seconds after completion of the dipyridamole infusion. Intravenous aminophylline (125 mg) was given immediately and the tachycardia was terminated. Two minutes later, thallium-201 was injected and subsequent myocardial imaging showed reversible perfusion defects in the inferior wall, septum, and apex. Coronary angiography revealed three-vessel disease. This case discloses that reversible perfusion defects can still be demonstrated on thallium scan in spite of injection of aminophylline, an antagonist of dipyridamole, before thallium administration.

Adult↗
PubMed2001

[Meaning of clinical and electrical positivity in the myocardial perfusion scintigraphy during the administration of dipyridamole].

BACKGROUND AND OBJECTIVES: Administration of dipyridamole produces angina and ST depression in 20%-30% and 6%-34% of patients, respectively. This study aimed to evaluate the clinical implications of the presentation of angina and/or ST depression during the administration of dipyridamole in the study of coronary heart disease by myocardial perfusion SPECT (MPS). METHODS: The study population is constituted by 593 consecutive patients without left branch block or ventricular pacemaker rhythm who were referred to our service to undergo MPS with dipyridamole. A SPECT was performed after the administration of 99mTc-tetrosfosmine and drug stimulation with dipyridamole (0.142 mg/kg/min for 4 minutes). A coronariography was performed in 338 patients (57%). The frequency of clinical and electrical positivity and their relationship with the MPS and the coronariography were studied. RESULTS: The rate of angina and ST depression was 32% (n = 190) and 10% (n = 58), respectively. Myocardial perfusion defects were observed in 465 patients (78%), and signs of scintigraphic ischemia in 311 (52%). The patients with ST depression presented a higher frequency of perfusion defects (93% vs 76%, p = 0.0012) and scintigraphic ischemia (89% vs 49%, p < 0.0001). In addition, perfusion defects in more than one territory were observed in these patients in a higher percentage (53% vs 34%, p = 0.0036). Among the patients who underwent cardiac catheterization, those who had a ST depression had a greater extension of coronary heart disease (1.8 +/- 1.2 vs 1.3 +/- 1.0 diseased vessels, respectively. p = 0.0100) and a higher frequency of multivessel disease (61% vs 43%, p = 0.0380). Those patients who had clinical positivity showed a scintigraphic ischemia more frequently (66% vs 47%, p < 0.0001), however no statistically significant differences were observed between the presence of patients with perfusion defects or in the extension of these defects as well as in the number of diseased vessels in the coronariographic study. CONCLUSIONS: During the administration of dipyridamole, the ST depression is associated with more frequent scintigraphic ischemia, larger extension of perfusion defects and more diseased vessels. The appearance of angina is associated with scintigraphic ischemia, but it is not necessarily associated with the extension of perfusion defects or greater number of diseased vessels.

Angina Pectoris↗
PubMed2000

[Assessment of the effects of dipyridamole and dobutamine on coronary microcirculation using myocardial contrast echocardiography].

OBJECTIVES: To evaluate the effects of dipyridamole and dobutamine on myocardial blood flow (MBF) and myocardial blood volume (MBV), and their ability to detect non-flow-limiting coronary stenoses with myocardial contrast echocardiography (MCE). METHODS: Thirteen closed-chest dogs were studied at 7-10 days after placement of ameroid constrictors around proximal coronary arteries and their branches. MBF was measured with radiolabeled microspheres and myocardial plateau video intensity (VI, which indicates relative MBV) and microbubble velocity (beta) were measured with MCE at rest, after dipyridamole (0.56 mg/kg), and during peak dobutamine dose (30-40 micrograms.kg-1.min-1). RESULTS: The effects of both agents on MBF were similar in abnormal and normal segments. Plateau VI increased more and beta increased less with dobutamine than dipyridamole (P < 0.05), but the plateau VI ratios and beta ratios between abnormal and normal segments were almost identical during both drugs (P < NS), resulting in similar perfusion defects. Excellent linear relations were found between the plateau VI ratio or beta ratio and MBF (derived from radiolabeled microspheres) ratio from abnormal and normal beds during dipyridamole and dobutamine. CONCLUSION: Although the effect of dipyridamole and dobutamine on MBV is different, they unmask MBF reserve to a similar extent. Thus, the quantification of stenosis severity is identical using both agents with MCE.

Animals↗
PubMed2001

[Comparison of dobutamine-stress magnetic resonance imaging and dipyridamole-TL-201-SPECT as alternative strategies for the detection of coronary artery dis in patients no suitable for stress echocardiography].

AIM: During the past decade stress-echocardiography has gained increasing popularity for detection of myocardial ischemia in patients with coronary artery disease. However, about 10% to 15% of the patients submitted for stress-echocardiography do not have an adequate acoustic window. The purpose of this study was to compare high-dose dobutamine-stress magnetic resonance imaging (dobutamine-MRI) with dipyridamole-Tl-201-SPECT (dipyridamole-SPECT) as alternative strategies for detection of myocardial ischemia in patients with inadequate image quality by stress-echocardiography. PATIENTS AND METHODS: Of 296 patients which were consecutively submitted to stress-echocardiography 45 patients (15%) had two or more segments that could not be evaluated according to the 16-segment-model of the American Society of Echocardiography. They underwent dobutamine-MRI and dipyridamole-SPECT studies, which were evaluated using a 28-segment modell. Myocardial segments were attributed to perfusion territories of the coronary arteries. The results of ischemia detection were compared to the results of coronary angiography (stenosis > or = 50%). RESULTS: In comparison to coronary angiography dobutamine-MRI yielded a sensitivity of 87%, a specificity of 86%, a positive predictive value of 93%, a negative predictive value of 75% and a diagnostic accuracy of 86%. For dipyridamole-SPECT results were 90%, 86%, 93%, 80% and 89%, respectively. These values were not significantly different. CONCLUSIONS: In patients not suitable for stress-echocardiography, both dobutamine-MRI and dipyridamole-SPECT are reliable strategies for detection of myocardial ischemia. Selection is dependent on the patient criteria, technical considerations, local logistics and experience of the observer.

Adrenergic beta-Agonists↗
PubMed1992

[Prognostic value of the dipyridamole-echocardiography test immediately after a non-complicated myocardial infarct: a large scale multicenter study. Echo Persantine Italian Cooperative Study].

BACKGROUND: Any new diagnostic test should follow a pathway similar to that of a new drug, from initial studies in highly selected populations under strictly controlled conditions, up to large scale multicenter trials more likely to represent the true performance of the test in the clinical arena. AIM OF THE STUDY: To evaluate the capability of prognostic stratification of high dose (up to 0.84 mg/kg over 10') dipyridamole-echocardiography test (DET) early after an acute myocardial infarction in a "phase IV" study, based upon 11 different echocardiographic laboratories, all with established experience in stress echo and fulfilling quality control requirements for stress echo readings. STUDY POPULATION: Nine-hundred twenty five patients were evaluated after a mean of 10 days from an acute myocardial infarction and followed up for a mean of 14 months. RESULTS: During DET, one major adverse reaction occurred, consisting of a prolonged ischemia resistant to aminophylline and nitrates, and progressing to small uncomplicated reinfarction. In 11 patients the lower dipyridamole dose (0.56 mg/kg over 4') gave limiting side effects. Patients were followed up for 14 +/- 9.9 months (range = 1.53). During the follow-up, there were 34 deaths and 37 non-fatal myocardial infarctions; 104 patients developed class III or IV angina, and 149 had coronary revascularization procedures (bypass or angioplasty). Considering all spontaneous events (angina, reinfarction and death), the most important univariate predictor was the result of DET (chi-square = 45.8). With a Cox analysis, echocardiographic positivity, age and sex were found to have an independent and additive value. Considering survival (and therefore death as the only event) age was the most meaningful parameter, followed by the Wall Motion Score Index during dipyridamole (chi-square = 12.1); among other parameters, the resting Wall Motion Score Index was a significant predictor of death. By Cox analysis, age (relative risk estimate = 1.02) and Wall Motion Score Index during dipyridamole (relative risk estimate = 14) showed an independent and additional prognostic value. In particular, considering death only, the event rate was of 2% in patients with negative DET, 4% in patients with high dose positive DET and 7% in patients with low dose positive DET. CONCLUSIONS: Dipyridamole echocardiography is feasible and safe early after uncomplicated myocardial infarction and allows an effective risk stratification on the basis of the presence, severity, extent and timing of the induced dyssynergy. In particular, the risk of death doubles in patients with high dose positivity and almost quadruples in patients with low dose positivity.

Adult↗
PubMed1992

[Quantitative thallium myocardial tomoscintigraphy. Value of intravenous infusion of dipyridamole after negative submaximal exercise test].

Patients with suspected coronary artery disease are sometimes unable to exercise adequately (85% of age calculated maximal heart rate) to validate their ergometric stress test. Some groups suggest performing dipyridamole scintigraphy from the outset but then the information provided by exercise stress testing is lost. The aim of this study was to compare scintigraphies performed after exercise alone and after exercise combined with dipyridamole using a method of quantification. Thirteen patients with ischaemic heart disease without necrosis (coronary lesions greater than 75% luminal narrowing in: 7 right coronary, 10 left anterior descending, 3 left circumflex arteries and 1 left main coronary artery with 50% luminal narrowing) underwent exercise stress testing followed by Thallium imaging. One week later, the same exercise stress test was performed followed by an intravenous injection of dipyridamole and Thallium scintigraphy. The circumference of the radioactivity was traced and the surface of each segment calculated in three different short axis views, subdivided into 4 segments (anterior, lateral, inferior and septal walls). Any segment vascularised by a stenosed coronary artery was considered to be underperfused (105 segments). The ratios of the surfaces of underperfused/normal segments were compared using the two study protocols. Segments of the same wall in the 3 short axis views were grouped in the same myocardial zone. Thirty five myocardial zones were thus obtained: 25 zones were more underperfused after combining exercise and dipyridamole than after simple exercise stress (p = 0.014). The average increase in underperfusion after the combined exercise-dipyridamole was 12.4% compared with 5.5% after exercise alone (p = 0.03). Secondary effects were minimal.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗
PubMed2005

Prognostic significance of dipyridamole-induced ST depression in patients with normal 82Rb PET myocardial perfusion imaging.

UNLABELLED: Recent studies have shown that vasodilator-induced ischemic electrocardiographic (ECG) changes have incremental prognostic value over normal SPECT myocardial perfusion imaging (MPI) and identify patients at higher risk for cardiac events. The prognostic value of vasodilator-induced ischemic ECG changes in the setting of normal PET MPI has yet to be determined. We sought to determine the prognostic importance of dipyridamole-induced ischemic ECG changes in patients with normal 82Rb PET myocardial perfusion images. METHODS: Between 2000 and 2003, 2,029 consecutive patients undergoing dipyridamole stress 82Rb PET at the University of Ottawa Heart Institute were evaluated. Patients with normal PET MPI and interpretable ECGs were enrolled. Electrocardiograms were assessed for ST depression or elevation and patients were categorized into those with and without dipyridamole-induced ischemic ECG changes. Images were graded using the 17-segment model. Follow-up information was obtained by telephone interview, from hospital records, or from treating physicians. All cardiac events (cardiac death, nonfatal myocardial infarction [MI], percutaneous coronary intervention, coronary artery bypass grafting, or angiography) were verified with hospital records. RESULTS: Of the 629 enrolled patients with normal PET MPI, 72 patients had dipyridamole-induced ischemic ECG changes. There was no significant difference between the 2 groups in the combined endpoint (cardiac death, nonfatal MI, and revascularization) at follow-up (mean +/- SD, 27.1 +/- 13 mo). There were no cardiac deaths in either group. One (1.4%) patient with ischemic ECG changes had a nonfatal MI (0.6% annual event rate). Two (2.8%) patients with ischemic ECG changes required revascularization compared with 11 (2.0%) in the nonischemic ECG group. CONCLUSION: Normal 82Rb PET confers an excellent prognosis regardless of dipyridamole-induced ST depression.

Dipyridamole↗
PubMed1991

Effects of aspirin, dipyridamole, and dibutyryl cyclic adenosine monophosphate on platelet-derived growth factor A chain mRNA levels in human saphenous vein endothelial cells and smooth muscle cells.

Aspirin and dipyridamole have frequently failed to control intimal hyperplasia in vascular grafts in animal and clinical trials. These trials were based on the concept that the smooth muscle mitogen, platelet-derived growth factor (PDGF) released from platelets, was a major cause of intimal hyperplasia. Both endothelial and smooth muscle cells (ECs and SMCs), however, can also release PDGF-like SMC mitogens that might cause intimal hyperplasia. We therefore tested whether aspirin and dipyridamole alone or together can affect PDGF-A chain mRNA levels in cultured human saphenous vein ECs and SMCs. Cultures were exposed for 72 hours to 3 x 10(-5) mol/L aspirin and/or 5 x 10(-6) mol/L dipyridamole. Cellular RNA was then extracted, and PDGF-A chain mRNA signal levels were measured by a reverse transcription/polymerase chain reaction method. mRNA for glyceraldehyde-3-phosphate dehydrogenase was used as a constitutively expressed control RNA species. Signal strength on Southern blots of amplified polymerase chain reaction products was measured by densitometry. Neither aspirin nor dipyridamole alone or together reduced the ratio (PDGF-A chain signal/glyceraldehyde-3-phosphate dehydrogenase signal) below that of control cultures. PDGF-A chain expression was not a constitutive artifact of culture because dibutyryl cyclic AMP (5 x 10(-4) mol/L) reduced PDGF-A chain signal from a control index of 1.0 to 0.5 +/- 0.1 (mean +/- SE) (n = 3; p less than 0.05) in EC cultures and to 0.2 (mean) (n = 2) in SMC cultures. These data may explain why aspirin and dipyridamole fail to reduce intimal hyperplasia in some animal and clinical trials despite effective inhibition of platelet aggregation.

Aspirin↗
PubMed1992

Effects of dipyridamole infusion on human renal function observed using technetium-99m-DTPA.

Our observation that a prolonged dipyridamole infusion reduced or eliminated blood clearance of Gd-DTPA in dogs led us to investigate if dipyridamole, infused intravenously at rates comparable to those used in thallium myocardial perfusion tests, would alter renal filtration in humans. Renal filtration was assessed using a bolus injection of 10 mCi of 99mTc-DTPA in five males (19-63 yr old) with normal serum urea and creatinine. Twenty minutes following the bolus injection a 10-min intravenous infusion of either dipyridamole (0.14 mg/kg/min) or saline sham was given. Four to 10 min following the start of the dipyridamole infusion, a paradoxical rise in counts in the kidney region of interest was observed and persisted for 10 to 27 min. During this time, a 13% to 52% (mean +/- s.d., 40% +/- 16%, p less than 0.007) reduction in the exponential slope defining the clearance of counts from the cardiac region of interest occurred (implying a reduction of glomerular filtration rate), mean heart rate increased 27 +/- 5 bpm, p less than 0.002 and mean diastolic pressure decreased 12.9 +/- 6.4 mmHg, p less than 0.028. This finding indicates that renal clearance of tracers such as thallium or contrast agents such as Gd-DTPA is reduced during dipyridamole infusion.

Adult↗