Magnitude of benefit from earlier thrombolytic treatment in acute myocardial infarction: new evidence from Grampian region early anistreplase trial (GREAT).

OBJECTIVE

To generalise from the results of the Grampian region early anistreplase trial (GREAT) and to express the benefit of earlier thrombolysis in terms of lives saved per hour of earlier treatment.

DESIGN

Multivariate analysis of a randomised double blind trial.

SETTING

29 rural practices in Grampian region and teaching hospitals in Aberdeen.

SUBJECTS

311 patients with suspected acute myocardial infarction and without contraindications to thrombolysis who were seen by their general practitioners within four hours of the start of symptoms.

INTERVENTIONS

Anisterplase 30 units given intravenously, either by general practitioners before hospitalisation or later in hospital.

MAIN OUTCOME MEASURE

Death within 30 months of entry into trial.

RESULTS

Death within 30 months was positively related to age (P < 0.0001) and to delay between start of symptoms and thrombolytic treatment (P = 0.0004). However, the probability of dying rose exponentially with earlier presentation, so death within 30 months was negatively related to the logarithm of the time of randomisation (P = 0.0163). In patients presenting two hours after start of symptoms each hour's delay in receiving thrombolysis led to the loss of 21 lives per 1000 within 30 days (95% confidence interval 1 to 94 lives per 1000) (P = 0.03) and 69 lives per 1000 within 30 months (16 to 141 lives per 1000) (P = 0.0004).

CONCLUSIONS

The magnitude of the benefit from earlier thrombolysis is such that giving thrombolytic treatment to patients with acute myocardial infarction should be accorded the same degree of urgency as the treatment of cardiac arrest.