Introduction

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Acute myocardial infarction is most often due to coronary thrombosis. Thrombolytic treatment, if given before myocardial necrosis becomes irreversible, is a radical treatment for this common and commonly fatal condition; giving thrombolytic treatment is a matter of great urgency.

A working group of the British Heart Foundation developed guidelines for the early management of acute myocardial infarction and recommended that thrombolytic treatment should be given to eligible patients within 90 minutes of their calling for medical help.¹ We report call to needle times in urban and rural areas in Grampian and consider strategies for the provision of thrombolytic treatment within the British Heart Foundation guidelines.

	Methods

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After meetings with general practitioners, in which they agreed to take part in this study, we developed a protocol for the management of patients with suspected acute myocardial infarction² and designed and printed a referral letter that prompted the recording of relevant times and included a checklist of the indications and contraindications for thrombolytic treatment. These were distributed to 42 "country" practices in Grampian that were 25 km or more from Aberdeen and referred patients to Aberdeen Royal Infirmary. The study was extended later to 34 city and suburban practices in Aberdeen closer to the hospital.

Patients with suspected acute myocardial infarction were identified on admission and followed through to discharge by an audit nurse (CS), who collated timing data extracted from referral letters, ambulance records, and hospital notes. Unless otherwise stated, time intervals are reported as medians.

Patients with suspected acute myocardial infarction seen by general practitioners were admitted directly to the coronary care unit or to general medical wards. Patients not seen by general practitioners but calling 999 for an ambulance were either taken to the accident and emergency department, where thrombolytic treatment was not given, and then transferred to the coronary care unit or, at the discretion of the ambulance crews, were taken directly to the coronary care unit after the unit was notified of their expected time of arrival.

	Results

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Records were obtained of 1986 episodes of suspected acute myocardial infarction; the diagnosis was confirmed on 1466 occasions; thrombolytic treatment was given on 1053 occasions. Seven patients were excluded, six had been flown from offshore, and one had been transferred by air from another region, leaving 1046 episodes which form the basis of this report. Of these, 544 were from country practices in Grampian and 502 from the city or suburbs of Aberdeen.

Country practices
General practitioners from country practices were called and attended patients before transfer to hospital on 97% (528/544) of occasions; only 3% of patients (16) were taken directly to hospital after a 999 call (table 1). When general practitioners gave opiate, the median call to opiate interval was 30 minutes; in patients not seen by general practitioners, the call to opiate interval was almost 60 minutes longer. The call to opiate interval was 130 minutes in those patients seen by a general practitioner and not given opiate but requiring it later in hospital.

City and suburbs
General practitioners from city and suburban practices were called and attended on 68% (340/502) of occasions (table 2). When they gave opiate it was given a median of 25 minutes after being called; when they were not involved, opiate was given about an hour after help had been requested by a 999 call.

	Discussion

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British Heart Foundation guidelines
The British Heart Foundation guidelines for the early management of patients with myocardial infarction recommend that all patients with obvious acute myocardial infarction and without contraindications should receive thrombolytic treatment within 90 minutes of alerting the medical or paramedical services.¹ The guidelines go on to recommend that "in localities where transport times to hospital are prolonged, or where delays in hospital are great, general practitioners should take the initiative for thrombolytic treatment." Other authorities have suggested that thrombolytic treatment should be initiated before the patient is transfered to hospital if travelling time is 30 minutes or more. ^{3 4}

Thrombolytic treatment in rural areas
In this study, practices designated as "country" were located 25 km or more from Aberdeen Royal Infirmary, to which all patients in the study were referred. The closest of the practices, Stonehaven, was linked with Aberdeen by a derestricted dual carriageway but had a median journey time of 30 minutes. Nearly 90% of journey times from country practices were 30 minutes or more.

Thrombolysis in conurbations
Two thirds of patients from the city and suburbs were seen by general practitioners before admission to hospital. When general practitioners gave opiate, the call to opiate interval was 25 minutes, similar to that in country practices. Patients calling 999 did not receive opiate until they were in hospital, and their call to opiate time averaged 60 minutes: slightly longer in those taken to the accident and emergency department, and slightly shorter in those taken directly to the coronary care unit. The length of the call to opiate time after "scoop and run" is explained by the double ambulance journey after a 999 call, the loading and unloading time, and the time taken for opiate to be prescribed by a doctor in the emergency department to which the patient is taken.

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 treatment of cardiac arrest. ^{8 9} On this principle, thrombolytic treatment should be given, if practicable, before the patient is transported, and by the first qualified person to see the patient. Only then is the British Heart Foundation's standard of a call to thrombolysis time within 90 minutes likely to be achieved for over 90% of patients.