The Pharmaceutical Journal
Vol 276 No 7402 p617
27 May 2006

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Dipyridamole and aspirin for stroke prevention

A combination of aspirin and dipyridamole is more effective than aspirin alone in the secondary prevention of stroke, according to research published in The Lancet last week (2006;367:1665).

The aspirin plus dipyridamole versus aspirin alone after ischaemia of arterial origin (ESPRIT) trial involved 2,739 patients. They received aspirin (30–325mg daily) with or without dipyridamole (200mg twice daily) within six months of a transient ischaemic attack or minor stroke of presumed arterial origin. Mean follow-up was 3.5 years. Median aspirin dose was 75mg in each group and 83 per cent of patients on the combination regimen received modified release dipyridamole.

The primary outcome event was the composite of death from all vascular causes, non-fatal stroke, non-fatal myocardial infarction (MI) or major bleeding complication, whichever happened first.

During the trial, 216 patients (16 per cent) in the aspirin alone group and 173 patients (13 per cent) in the combination group had at least one primary outcome event (hazard ratio 0.80, 95 per cent confidence interval 0.66–0.98; absolute risk reduction 1 per cent per year, CI 0.1–1.8). The absolute risk reduction corresponds with a number needed to treat of 104. A total of 470 patients (34 per cent) in the combination group discontinued the study drugs, mainly because of headache. And 13 per cent of patients in the monotherapy group discontinued aspirin.

The researchers incorporated data from the ESPRIT trial into a previous meta-analysis and calculated that the overall risk ratio for vascular death, non-fatal stroke or non-fatal MI was 0.82 (CI 0.74–0.91).

The author of an accompanying comment says that the study raises no concerns about the adverse effects of aspirin plus dipyridamole on coronary heart disease. “The hazard ratio of all cardiac events was well in line with the primary outcome composite, and there was no initial clustering of angina or myocardial infarction,” he said (ibid, p1638).

The National Institute for Health and Clinical Excellence published guidance on dipyridamole last year (PJ, 28 May 2005, p641). It recommended that modified-release dipyridamole can be used in combination with aspirin to prevent strokes and heart attacks for a period of two years. Thereafter, preventive therapy should revert to standard care, it said.