Objective To assess whether upper arm ischaemia influences exercise-induced myocardial ischaemia and platelet activation in patients with coronary artery disease (CAD).

Design Crossover study.

Setting University hospital.

Patients Twenty patients (17 men) of mean±SD age 64±8 years with stable CAD.

Interventions Patients underwent two exercise stress tests (ESTs) on two separate days in a randomised manner: (1) a maximal EST only (EST-1); (2) a maximal EST after intermittent upper arm ischaemia (cycles of alternating 5-min inflation and 5-min deflation of a standard blood pressure cuff) (EST-2). Blood samples were obtained to evaluate platelet reactivity.

Main outcome measures Platelet reactivity was assessed by flow cytometry at rest and after EST, with and without ADP stimulation, by measuring the percentage of monocyte-platelet aggregates (MPAs) and CD41 platelet expression measured as mean fluorescence intensity.

Results Remote ischaemia had no significant effect on EST-induced myocardial ischaemia. At rest there were no differences before EST-1 and EST-2 in basal MPA (20.7±2.3 vs 20.8±2.4, p=0.56) and CD41 (21.5±2.3 vs 21.3±2.3, p=0.39), and ADP stimulation induced a similar increase in both MPA (+15.2±8.2% vs +14.9±8.4%, p=0.71) and CD41 (+15.7±5.7% vs 13.37±6.9%, p=0.59). While no differences in the increase in MPA and CD41 expression were observed after EST-1 and EST-2, ADP stimulation after EST-2 induced a lower increase in MPA (+18.3±8.1% vs +27.9±9.7%, p<0.001) and CD41 (+18.3±9.2% vs +27.2±12.4%, p<0.001) than after EST-1.

Conclusion These results show that, in patients with stable CAD, remote ischaemia induces protection against an exercise-related increase in platelet reactivity.