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PubMedDate not supplied

Prognostic value of dipyridamole sestamibi single-photon emission computed tomography and dipyridamole stress echocardiography for new cardiac events after an uncomplicated myocardial infarction.

A high-dose dipyridamole stress test (0.84 mg/kg in 6 minutes) with simultaneous sestamibi single-photon emission computed tomographic (SPECT) and echocardiographic imaging was performed in 89 patients before hospital discharge after an uncomplicated myocardial infarction. The aim of this study was to determine the prognostic value of these tests for new cardiac events and to compare the relative values of SPECT and echocardiography in a postinfarction dipyridamole stress test. Two years after infarction, nine patients (10%) had died, five patients (6%) had suffered a nonfatal reinfarction, and 14 patients (16%) had been readmitted to the hospital for a revascularization procedure. Cardiac death had occurred in 5 (10%) of 48 patients with a positive SPECT versus 4 (10%) of 41 with a negative SPECT (difference not significant) and in 6 (19%) of 31 with a positive echocardiogram versus 3 (5%) of 56 with a negative echocardiogram (p = 0.05). Cardiac death or reinfarction had occurred in 8 (17%) of 48 patients with a positive SPECT versus 6 (15%) of 41 with a negative SPECT (difference not significant) and in 6 (19%) of 31 with a positive echocardiogram versus 8 (14%) of 56 with a negative echocardiogram (difference not significant). Thus the predictive value of the dipyridamole stress test for new cardiac events after an uncomplicated myocardial infarction was limited, irrespective of the method used to detect ischemia. Reversible perfusion defects were identified more frequently than new wall motion abnormalities but did not predict late events. A positive dipyridamole echocardiogram was associated with a higher late mortality rate but did not predict other cardiac events.

Angioplasty, Balloon, Coronary↗
PubMed2000

Assessment of coronary flow reserve with transthoracic Doppler echocardiography: comparison among adenosine, standard-dose dipyridamole, and high-dose dipyridamole.

Coronary flow reserve (CFR), defined as a ratio of hyperemic-to-basal coronary flow velocity, provides important information about the functional aspect of coronary circulation. However, it usually is determined by invasive methods during catheterization. Recent studies have shown that transthoracic Doppler echocardiography (TTDE) may be useful in the measurement of coronary flow velocity in the distal portion of the left anterior descending coronary artery (LAD). The vasodilators used for hyperemia are adenosine and dipyridamole. However, the coronary vasodilative response and systemic hemodynamic effects of the two agents have not been directly compared with TTDE. We assessed blood flow velocity and vascular resistance in the distal LAD by TTDE during an intravenous 2-minute adenosine infusion (140 microg/kg/min) and low- (0.56 mg/kg) and high-dose dipyridamole (0. 84 mg/kg) infusion in 25 patients with patent LAD. Coronary flow velocity was successfully recorded in 20 patients (80%) during baseline and the consecutive vasodilator-infusion period. Compared with low-dose dipyridamole, adenosine infusion induced a higher CFR (3.7 +/- 0.87 vs 2.73 +/- 0.65; P <.05) and a lower coronary resistance index (0.31 +/- 0.04 vs 0.35 +/- 0.08; P <.05). But by increasing the dipyridamole dose to 0.84 mg/kg, the values of the CFR and coronary resistance index became comparable to those of adenosine infusion (2.85 +/- 0.78 vs 3.03 +/- 0.7, P = not significant [NS]; 0.33 +/- 0.04 vs 0.32 +/- 0.09, P = NS; respectively). We conclude that adenosine seems to be a favorable vasodilator for the measurement of CFR with TTDE.

Adenosine↗
PubMed2001

Dipyridamole stress echocardiography vs dipyridamole sestamibi scintigraphy for diagnosing coronary artery disease in left bundle-branch block.

STUDY OBJECTIVES: To evaluate dipyridamole stress echocardiography (DSE) for predicting coronary artery diseases (CADs) in patients with complete left bundle-branch block (LBBB). DESIGN: Comparison of DSE and dipyridamole sestamibi myocardial perfusion scintigraphy (sestamibi). SETTING: Tertiary-care cardiac referral center. PATIENTS: Fifty-four consecutive patients (26 men; mean [+/- SD] age, 59 +/- 7 years) with complete LBBB (14 patients with left ventricular [LV] dilatation) and intermediate probability of CAD. METHODS: Simultaneous single photon emission CT scan (20 mCi technetium Tc 99m stress/rest sestamibi) and echocardiography (second harmonic imaging) during a two-step (0.56 to 0.84 mg/kg) dipyridamole infusion protocol. Two sestamibi readings were performed. The first reading considered only those studies with reversible defects (sestamibi-1) to be positive. The second reading considered those studies with any defect (sestamibi-2) to be positive. CAD was defined as a >or= 50% reduction in diameter in at least one major vessel seen on coronary angiography. RESULTS: CAD was present in 17 patients (31.5%). The global predictive accuracy for CAD was significantly higher for DSE (87.0%) and sestamibi-1 (79.6%) than for sestamibi-2 (57.4%) [p < 0.01 vs DSE; p < 0.05 vs sestamibi-1]. No significant differences in sensitivity were present, but specificity was significantly higher for DSE (94.6%) and sestamibi-1 (81.1%) than for sestamibi-2 (43.2%; p < 0.01 vs both the other two tests). Of 14 patients with LV dilatation, 26.8% were falsely positive for CAD (in some cases for posterior defects) as determined by sestamibi-1 and 64.3% were falsely positive for CAD by sestamibi-2 vs none by DSE. CONCLUSIONS: DSE is at least as accurate as dipyridamole sestamibi scintigraphy for predicting CAD in patients with complete LBBB and tends to be more specific in those patients with underlying LV dilatation.

Bundle-Branch Block↗
PubMed1983

Trial of combined warfarin plus dipyridamole or aspirin therapy in prosthetic heart valve replacement: danger of aspirin compared with dipyridamole.

Despite the use of oral anticoagulation in patients with prosthetic heart valves, persistent thromboembolism over time warrants a search for improved methods of prevention. Thus, patients receiving 1 or more mechanical prosthetic heart valves were randomized to therapy with warfarin plus dipyridamole (400 mg/day) or warfarin plus aspirin (500 mg/day) on the basis of location and type of valve and surgeon, and followed up with a concurrent, nonrandomized control group taking warfarin alone. In 534 patients followed up 1,319 patient-years, excessive bleeding (necessitating blood transfusion or hospitalization) was noted in the warfarin plus aspirin group (23 of 170 [14%], or 6.0/100 patient-years) compared with warfarin plus dipyridamole (7 of 181 [4%], or 1.6/100 patient-years, p less than 0.001), or warfarin alone (9 of 183 [5%], or 1.8/100 patient-years, p less than 0.001). A trend was evident toward a reduction in thromboembolism in the warfarin plus dipyridamole group (2 of 181 [1%], or 0.5/100 patient-years) as compared with warfarin plus aspirin (7 of 170 [4%], or 1.8/100 patient-years), or warfarin alone (6 of 183 [4%], or 1.2/100 patient-years). Adequacy of anticoagulation (based on 12,720 prothrombin time determinations) was similar in all 3 groups with 65% of prothrombin times in the therapeutic range (1.5 less than or equal to prothrombin time/control less than or equal to 2.5), 30% too low, and 5% too high. Warfarin plus aspirin therapy resulted in excessive bleeding and is contraindicated. Longer follow-up study is needed to determine whether further separation of the incidence of thromboembolism can be detected.

Aspirin↗
PubMed1987

Low-dose acetylsalicylic acid (ASA) plus dipyridamole versus dipyridamole alone in the prevention of stroke in patients with reversible ischemic attacks.

A total of 243 patients who had reversible ischemic attacks (RIA) were submitted to clinical trial to determine whether dipyridamole (400 mg/day) (D) or aspirin (100 mg/48 hours) + dipyridamole (300 mg/day) (ASA + D) would produce significant reduction in the subsequent occurrence of RIA and completed stroke. One hundred and fifteen were selected for Group ASA + D and 71 were treated with dipyridamole only. The treatment groups were similar in relation to age, sex, risk factors, duration and presumed vascular territory of RIA, incidence of alterations of arterial supra-aortic trunks, cerebral infarct (CT scan), and platelet function. Patients were followed for a mean time of 21 months. At the end of the study, 21.7% of the ASA + D group and 19.7% in the D group had suffered new episodes of RIA or completed stroke (p = 0.88). Frequency of stroke (reversible ischemic neurologic deficit or completed stroke) was 7.8% in the ASA + D patients and 9.8% in the D patients (p = 0.83). Subgroup analysis did not show significant differences either. It is concluded that ASA + D has no significantly greater beneficial effect than that observed with D alone in the secondary prevention of atherothrombotic cerebral ischemia. However, a statistical Type II error cannot be excluded by the reduced number of recurrences.

Adult↗
PubMed1999

Cost-effectiveness analysis of antiplatelet therapy in the prevention of recurrent stroke in the UK. Aspirin, dipyridamole and aspirin-dipyridamole.

OBJECTIVES: To evaluate the cost effectiveness from a UK health and social services perspective of antiplatelet therapies tested in the Second European Stroke Prevention Study (ESPS-2) in preventing recurrent stroke. To demonstrate the value of modelling studies in this area. DESIGN AND SETTING: A decision-analytic model was developed to evaluate health outcomes and associated costs. Sources of data for efficacy, adverse events, background event risks, disability and mortality were ESPS-2, the Oxfordshire Community Stroke Project and UK national statistics. Published national unit costs were applied to clinician panel estimates of resource use for acute stroke, rehabilitation and long term care. Outcome measures were strokes or disabled life-years averted, and disability-free, stroke-free or quality-adjusted life-years gained. PATIENTS AND INTERVENTIONS: 30-day survivors of ischaemic stroke treated with low dose aspirin, modified-release dipyridamole; the coformulation of low dose aspirin plus modified-release dipyridamole, or no antiplatelet therapy. MAIN OUTCOME MEASURES AND RESULTS: The model predicted that over 5 years the coformulation prevented 29 more strokes than aspirin alone per 1000 patients, at an additional cost of 1900 Pounds per stroke averted (1996 values). Over 5 years, each antiplatelet therapy was cost saving compared with no therapy. Results were sensitive to the cost of acute care, the cost of long term care of disabled stroke survivors, the effectiveness of therapy and the background risk of recurrent stroke. In sensitivity analyses, the cost effectiveness did not exceed 7000 Pounds per stroke averted or 11,000 Pounds per quality-adjusted life-year (QALY) gained, except when varying the effectiveness parameter. CONCLUSIONS: Application of a decision-analytic model to the results of ESPS-2 indicated that first-line therapy with the coformulation of modified-release dipyridamole and low dose aspirin to patients with a previous ischaemic stroke is likely to generate significant health benefits at modest extra costs to health and social services. The extra costs of treatment are balanced by the savings in future costs of acute care and long term care of the disabled. Future economic evaluations in this area should pay particular attention to the cost perspective, the duration of analysis, the selection of trials from which effectiveness data are derived, and the impact of the pooling of outcome events with potentially different economic consequences.

Aged↗
PubMed1995

[Diagnostic value of echocardiography with dipyridamole in coronary disease and evaluation of its prognostic potentiality face to ergometry, plane dipyridamole Tc99m-MIBI myocardial perfusion scintigraphy and coronary cineangiography].

PURPOSE: To assess in a consecutive series of patients, the diagnostic accuracy of dipyridamole echocardiography and to compare its prognostic power with that from other tests. METHODS: Seventy eight patients prospectively were underwent to dipyridamole echocardiography (DET) and coronary arteriography for diagnostic and post-infarction investigation. The majority was underwent to treadmill stress test and Tc99MIBI-dipyridamole planar myocardial scintigraphy. Eleven variables with possible prognostic importance were analyzed in a stepwise model to identify independent predictors of events. RESULTS: Sensitivity and specificity for the presence of coronary artery disease (in non-M patients) and multivessel disease (in post-MI patients) were, respectively, 44%, 91%, 53% and 88%. Mean follow-up was 21 +/- 9 months, during which there were four deaths, four unstable angina episodes, four nonfatal myocardial infarctions and eight revascularization procedures. By multivariate analysis, the only independent predictor of events was the change in wall motion score index from rest to peak stress. CONCLUSION: DET is a valuable alternative to exercise stress test and myocardial perfusion scintigraphy. Semiquantitative estimation of ischemic area during pharmacological stress is an important prognostic marker.

Chi-Square Distribution↗
PubMed1996

Comparison of ultrafast dipyridamole magnetic resonance imaging with dipyridamole SestaMIBI SPECT for detection of perfusion abnormalities in patients with one-vessel coronary artery disease: assessment by quantitative model fitting.

The value of ultrafast MRI for detection of myocardial perfusion abnormalities in patients with coronary artery disease (CAD) was assessed in 10 patients with stable angina pectoris and angiographically proven one-vessel CAD using double-level short-axis ultrafast MRI with bolus injection of gadolinium-DTPA and tomographic technetium-99m SestaMIBI imaging (SPECT) during dipyridamole-induced coronary hyperemia. Abnormally perfused regions were assessed with SPECT and MRI in all (100%) patients. Agreement in localization between arteriography and SPECT was 80%; between arteriography and MR, 70%; and between SPECT and MR, 90%. The signal intensity increase after the bolus injection of gadolinium-DTPA using a linear fit, and the slope of gadolinium-DTPA wash-in using double exponential model fitting were significantly different between abnormally and normally perfused regions. These preliminary results demonstrate the potential of dipyridamole ultrafast MR to monitor stress-induced flow maldistribution in patients with single vessel CAD.

Aged↗
PubMed1992

Usefulness of dipyridamole-echocardiographic test to identify jeopardized myocardium after thrombolysis. Limited clinical predictivity of dipyridamole-echocardiographic test in convalescing acute myocardial infarction: correlation with coronary angiography.

A dipyridamole-echocardiographic test (DET) was carried out to find out how safe and useful it was in predicting clinical outcome and in identifying patients at risk. The test was performed in 107 asymptomatic patients early (5 to 8 days) after a first acute uncomplicated myocardial infarction managed with thrombolytic therapy. All patients were followed up for a mean of 15 months and 94 underwent coronary angiography. The test was considered positive if transient asynergy of contraction was newly detected either in the infarct and adjacent areas or in the remote zones; two subsets were studied, according to the dose of dipyridamole (0.56 or 0.84 mg.kg-1) needed to induce ischaemia. The test was accomplished satisfactorily in 96% of patients. Intra-inter-observer agreements were 88% and 91% respectively. The test also proved safe at the high infusion dose. During the follow-up period, two patients died, one experienced re-infarction and 12 (12%) developed recurrence of angina. DET was abnormal in 32 patients (adjacent and remote asynergy in 28 and four patients respectively): 18 had a critical and two a non-critical stenosis in the infarct-related vessel, and nine had an occluded artery with collateral distal flow. Multivessel disease was present in 11 patients considered positive, four in the remote and seven in the adjacent zones. However, 20 patients with negative DET results had multivessel disease. Of the positive DET patients, seven had angina. There were eight total events in the 71 negative DET patients, five of whom had multivessel disease. Abnormality was more pronounced in positive DET patients, but did not influence the outcome.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Dipyridamole echocardiography and 99mTc-MIBI spect dipyridamole scintigraphy for cardiac evaluation prior to peripheral vascular surgery.

Coronary artery disease accounts for most of the early and late mortality and morbidity associated with vascular surgery. Cardiac pre-operative evaluation is mandatory for the assessment of cardiac risk. The aim of this study is to compare dipyridamole scintigraphy with 99mTc-MIBI (MIBI-dipy) and dipyridamole echocardiography (ECHO-dipy) and to evaluate their capability in identifying cardiac risk for strong events such as death, unstable angina or myocardial infarction. METHODS. Sixty consecutive patients (mean age 67 +/- 7) were enrolled. 52 performed ECHO-dipy, 51 MIBI-dipy. 40 patients went to aorto-femoral or aorto-iliac graft replacement and 15 to vascular angioplasty. Five patients did not undergo surgery. RESULTS. Eighteen patients (30%) had stress defects and 9 patients also rest defects with MIBI-dipy. Six patients new asinergic areas at ECHO-dipy. Three pts died in the first year follow-up for a cerebrovascular event, a myocardial infarction and a sudden death respectively. Sensitivity and specificity, positive and negative predictive value were 100%, 69%, 16%, 100% for MIBI-dipy and 66%, 94%, 40%, 98% for ECHO-dipy. CONCLUSIONS. As other authors reported, stress scintigraphy is a pre-operative test showing high sensitivity but with no satisfying specificity. Stress echocardiography, in our population, can produce a good negative predictive value. It is a less expensive and widespread clinical tool useful in the evaluation of preoperative patients. Its positive predictive power is not satisfying but it is shared with all non-invasive pre-operative tests available now.

Aged↗
PubMed1993

[Comparison of dipyridamole Tc-99m myocardial imaging with dipyridamole electrocardiogram in detecting coronary artery disease].

The authors compared the results of dipyridamole myocardial-SPECT (D-ECT) with dipyridamole electrocardiogram (D-ECG) in detecting coronary artery disease (CAD). According to the result of coronary artery angiogram. We analysed the results of D-ECT and D-ECG in 62 patients. In detecting CAD, the sensitivity and specificity of D-ECT were 89%, and 92%, while those of D-ECG were 54% and 76% respectively. In detecting single double, triple vessel diseases, the sensitivity of D-ECT was 76%, 100% and 100% respectively. The sensitivity of D-ECG was 35%, 73% and 67% respectively. In identifying left anterior descending, left circumflex and right coronary artery, the sensitivity of D-ECT was 73%, 80% and 80% respectively, while that of D-ECG was 54%, 20% and 25% respectively. The results showed that D-ECT was better than D-ECG in diagnosing CAD.

Adult↗
PubMed1998

Comparing a High-Dose Dipyridamole SPECT Imaging Protocol with Dobutamine and Exercise Stress Testing Protocols. Part II: Using High-Dose Dipyridamole to Determine Lung-to-Heart Ratios.

Determination of the severity of coronary artery disease (CAD) by single photon emission computed tomography (SPECT) imaging has previously been shown to have greater sensitivity, specificity, and accuracy when performed with pharmacologic stress using high-dose dipyridamole (HDD), than by standard dose dipyridamole (SDD) or exercise stress (EST) prior to SPECT imaging. The use of lung-to-heart (L:H) ratios has been shown to be valuable in determining the presence or absence of left main (LM) or triple vessel (3V) CAD. Fifty-four patients were studied; HDD (n = 40) or EST (n = 14) was used for the study. These patients underwent L:H ratio analysis, in which anterior views were used 5-10 minutes after the injection of 3 mCi of T1-201. Results of the L:H ratios were compared with the diagnosis of epicardial CAD, as determined by coronary (CA) arteriography. Patients who were "stressed" using either HDD or EST demonstrated statistically greater (p < 0.001) L:H ratios if they had LM/3V CAD when compared with patients who had 0-2 significantly stenosed coronary arteries. Though L:H ratios were greater when HDD pharmacologic stress was used, there was no statistical (p = NS) differences between the two groups. Increased L:H ratios with HDD and EST provide excellent markers for LM/3V CAD using T1-201 imaging. Coupled with previously reported SPECT data, the use of HDD shows promise for increasing the diagnostic accuracy of SPECT imaging.

Journal Article↗
PubMed1993

Effects of dipyridamole, pentoxifylline or dipyridamole plus pentoxifylline on platelet reactivity in patients with ischemic cerebrovascular insufficiency.

Platelet activation and the subsequent platelet recruitment induced by activated platelets released products constitute the initial events of platelet thrombus formation. We have evaluated the recruiting activity of collagen-stimulated whole blood in patients with ischemic cerebrovascular insufficiency. This was done using an experimental approach that allows independent evaluation of platelet activation and recruitment. The effects of of treating the patients with dipyridamole (DIP) (300 mg/day), pentoxifylline (POX) (1200 mg/day) or a combination of the two drugs at the same doses was also evaluated before and after 7, 15, and 45 days of treatment. DIP decreased the recruiting activity in a time-dependent manner, while POX did not show any effect. However, the combined treatment with DIP+POX was more effective than DIP alone in reducing platelet recruitment, which was abolished after 45 days of treatment. Studies using the drugs in vitro indicated a greater inhibitory activity of the drug association than either drug individually. The effects of the drug association in vitro, even at high concentrations, was lower than those observed ex vivo after 45 days of treatment. This suggests that DIP+POX in vivo may have effects that condition a reduced platelet response.

Aged↗
PubMed1991

Comparison of dipyridamole-echocardiography with dipyridamole-thallium scintigraphy for the diagnosis of myocardial ischemia.

After an intravenous infusion of dipyridamole (0.56 mg/kg), we performed both echocardiography and thallium scintigraphy in 63 patients who were referred for known or suspected coronary artery disease. Of those patients, 25 returned for coronary arteriography within 1 month after the tests, thus forming the study group for this report. Sensitivity for detection of coronary artery disease, when analyzed region-by-region, was 80% for thallium scintigraphy and 57% for echocardiography, whereas specificity was 85% and 98%, respectively. When evaluating individual patients for the presence or absence of ischemia, we found a sensitivity of 95% for scintigraphy and 58% for echocardiography; corresponding specificities were 50% and 100%. By using arteriography as the gold standard for comparison, it appears that thallium scintigraphy has a significantly higher sensitivity but lower specificity for the detection of coronary artery disease than does echocardiography. Echocardiography may, however, be a useful adjunct to thallium scintigraphy in the evaluation of patients with coronary artery disease.

Coronary Disease↗
PubMed1994

Dipyridamole-dobutamine echocardiography: a novel test for the detection of milder forms of coronary artery disease.

OBJECTIVES: This study was designed to assess the clinical, hemodynamic and diagnostic effects of the addition of dobutamine to dipyridamole echocardiography. BACKGROUND: Pharmacologic stress echocardiography with either dipyridamole or dobutamine has gained acceptance because of its safety, feasibility, diagnostic accuracy and prognostic power. The main limitation of the two tests is a less than ideal sensitivity in some patient subsets, such as those with limited coronary artery disease. We hypothesized that two pharmacologic stresses might act synergistically in the induction of ischemia by combining the mechanisms of inappropriate coronary vasodilation (with dipyridamole) and an increase in myocardial oxygen consumption (with dobutamine). METHODS: One hundred fifty patients (mean [+/- SD] age 51 +/- 11 years) referred for stress echocardiography were initially studied by dipyridamole-dobutamine echocardiography. The test was stopped during the dipyridamole step in 95 patients for achievement of a predetermined end point (obvious dyssynergy induced by lower or higher dipyridamole dose), and dipyridamole-dobutamine tests were performed in 55 patients (negative dipyridamole echocardiographic test). In the same 150 patients the dobutamine echocardiographic test (up to 40 micrograms/kg body weight per min) was performed on a separate day. RESULTS: Significant coronary artery disease (> 50% diameter stenosis of at least one major coronary vessel by quantitative coronary arteriography) was present in 131 patients (one vessel in 115; two vessels in 10, three vessels in 6), with normal coronary arteriography in 19. The feasibility of the dipyridamole-dobutamine test was 96%. Self-limiting side effects occurred in 5% of patients. The peak rate-pressure product was lowest during the dipyridamole test (132 +/- 30) and was comparable during the dobutamine (186 +/- 59) and dipyridamole-dobutamine tests (179 +/- 45, p = NS vs. dobutamine; p < 0.01 vs. dipyridamole). Sensitivity was 71% for dipyridamole, 75% for dobutamine and 92% for dipyridamole-dobutamine echocardiography (dipyridamole vs. dipyridamole-dobutamine, p < 0.01; dobutamine vs. dipyridamole-dobutamine, p < 0.01; dipyridamole vs. dobutamine, p = NS), whereas specificity was 89% for dipyridamole, 79% for dobutamine and 89% for dipyridamole-dobutamine echocardiography (p = NS for all). CONCLUSIONS: Routine dobutamine addition to dipyridamole stress testing is clinically useful and well tolerated. It expands the spectrum of the disease detectable by pharmacologic stress echocardiography and allows documentation of milder forms of coronary artery disease that can be missed by conventional dipyridamole or dobutamine stress echocardiography.

Adult↗
PubMed2004

Clinical effectiveness and cost-effectiveness of clopidogrel and modified-release dipyridamole in the secondary prevention of occlusive vascular events: a systematic review and economic evaluation.

OBJECTIVES: To examine the clinical effectiveness and cost-effectiveness of two alternative antiplatelet agents, clopidogrel and modified-release (MR)-dipyridamole, relative to prophylactic doses of aspirin for the secondary prevention of occlusive vascular events. DATA SOURCES: Electronic databases. REVIEW METHODS: A total of 2906 titles and abstracts were rigorously screened and 441 studies were assessed in detail. Two RCTs were identified. For the assessment of cost-effectiveness, eight reviews were identified. The results were presented in structured tables and as a narrative summary. No additional clinical effectiveness data were presented in either of two company submissions. All economic evaluations (including accompanying models) included in the company submissions were assessed. Following this analysis, if the existing models (company or published) were not sufficient, a de novo model or modified versions of the models were developed. RESULTS: In the CAPRIE trial the point estimate for the primary outcome, i.e. ischaemic stroke, myocardial infarction (MI) or vascular death, favoured clopidogrel over aspirin, but the boundaries of the confidence intervals raise the possibility that clopidogrel is not more beneficial than aspirin. In terms of the secondary outcomes reported, there was a non-significant trend in favour of clopidogrel over aspirin but the boundaries of the confidence intervals on the relative risks all crossed unity. There was no difference in the number of patients ever reporting any bleeding disorder in the clopidogrel group compared with the aspirin group. The incidences of rash and diarrhoea were statistically significantly higher in the clopidogrel group than the aspirin group. Patients in the aspirin group had a higher incidence of indigestion/nausea/vomiting than patients in the clopidogrel group. Haematological adverse events were rare in both the clopidogrel and aspirin groups. No cases of thrombotic thrombocytopenic purpura were reported in either group. Treatment with MR-dipyridamole alone did not significantly reduce the risk of any of the primary outcomes reported in ESPS-2 compared with treatment with aspirin. ASA-MR-dipyridamole was significantly more effective than aspirin alone in patients with stroke or transient ischaemic attacks (TIAs) at reducing the outcome of stroke and marginally more effective at reducing stroke and/or death. Treatment with ASA-MR-dipyridamole did not statistically significantly reduce the risk of death compared to treatment with aspirin. The number of strokes was statistically significantly reduced in the ASA-MR-dipyridamole group compared with the MR-dipyridamole group. In terms of the other primary outcomes, stroke and/or death and death, the results favoured treatment with ASA-MR-dipyridamole but the findings were not statistically significant. There was no difference in the number of bleeding complications between the ASA-MR-dipyridamole and aspirin groups. The incidence of bleeding complications was significantly lower in the MR-dipyridamole treatment group. More patients in the MR-dipyridamole treatment groups experienced headaches compared to patients receiving treatment with aspirin alone. The York model assessed the cost-effectiveness of differing combinations of treatment strategies in four patient subgroups, under a number of different scenarios. The results of the model were sensitive to the assumptions made in the alternative scenarios, in particular the impact of therapy on non-vascular deaths. CONCLUSIONS: Clopidogrel was marginally more effective than aspirin at reducing the risk of ischaemic stroke, MI or vascular death in patients with atherosclerotic vascular disease, however, it did not statistically significantly reduce the risk of vascular death or death from any cause compared with aspirin. There was no statistically significant difference in the number of bleeding complications experienced in the clopidogrel and aspirin groups. MR-dipyridamole in combination with aspirin was superior to aspirin alone at reducing the risk of stroke and marginally more effective at reducing the risk of stroke and/or death. Compared with treatment with MR-dipyridamole alone, MR-dipyridamole in combination with aspirin significantly reduced the risk of stroke. Treatment with MR-dipyridamole in combination with aspirin did not statistically significantly reduce the risk of death compared with aspirin. Compared with treatment with MR-dipyridamole alone, bleeding complications were statistically significantly higher in patients treated with aspirin and MR-dipyridamole in combination with aspirin. Due to the assumptions that have to be made, no conclusions could be drawn about the relative effectiveness of MR-dipyridamole, alone or in combination with aspirin, and clopidogrel from the adjusted indirect comparison. The following would apply for a cost of up to GBP20,000-40,000 per additional quality-adjusted life-year. For the stroke and TIA subgroups, ASA-MR-dipyridamole would be the most cost-effective therapy given a 2-year treatment duration as long as all patients were not left disabled by their initial (qualifying) stroke. For a lifetime treatment duration, ASA-MR-dipyridamole would be considered more cost-effective than aspirin as long as treatment effects on non-vascular deaths are not considered and all patients were not left disabled by their initial stroke. In patients left disabled by their initial stroke, aspirin is the most cost-effective therapy. Clopidogrel and MR-dipyridamole alone would not be considered cost-effective under any scenario. For the MI and peripheral arterial disease subgroups, clopidogrel would be considered cost-effective for a treatment duration of 2 years. For a lifetime treatment duration, clopidogrel would be considered more cost-effective than aspirin as long as treatment effects on non-vascular deaths are not considered. It is suggested that the combination of clopidogrel and aspirin should be evaluated for the secondary prevention of occlusive vascular events. Also randomised, direct comparisons of clopidogrel and MR-dipyridamole in combination with aspirin are required to inform the treatment of patients with a history of stroke and TIA, plus trials that compare treatment with clopidogrel and MR-dipyridamole for the secondary prevention of vascular events in patients who demonstrate a genuine intolerance to aspirin.

Aspirin↗