Thrombolysis for elderly patients with myocardial infarction: experience in an integrated unit

Age and Ageing,  May, 1994  by Gwenno M. Batty,  D.S. Parry,  W.E. Wilkins,  A.G. Chappell

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The Departments of Medicine and Geriatrics were integrated in the Ogwr Health Unit in 1984. Since then there has been a non-age-related acute admissions policy which has led to early, intensive investigations and appropriate treatment of all patients according to need rather than age. A retrospective analysis of the use of thrombolytic agents over a 12-month period in patients aged 65 or over was undertaken to assess whether our principles extended to care of elderly patients admitted with acute myocardial infarction. High rates of prescription of thrombolytic agents in the elderly were achieved by endorsing the philosophy that age contributes little to the prediction of patient outcome and should not be considered in patient management.

Introduction

In recent years the advent of thrombolysis has dramatically changed the management of patients with acute myocardial infarction. Large randomized controlled clinical trials carried out in the late 1980s excluded elderly patients (1)(2). Others included patients of all ages but showed conflicting results. The Gissi 1 trial (3) showed that the reduction in mortality with thrombolysis reached statistical significance in patients under 65 years only, whilst some authors (4) suggested that patients over 75 years old should not routinely be receiving thrombolytic therapy. ISIS-2 (5) however showed that thrombolysis achieved the greatest reduction in absolute mortality in those at highest risk of death, notably the elderly, but the interpretation of these trials by some authors has led to the publication of controversial guidelines with respect to thrombolysis for elderly patients (6)(7). Elderly patients sustaining an acute myocardial infarction (AMI) have a poorer prognosis than younger patients (8). Their chances of survival might be expected to improve with admission to a coronary care unit (CCU) and by administration of thrombolytic agents when indicated. In spite of this, age-related policies still exist in many hospitals (9).

In this paper we analyse 12 months' experience in the management of patients aged 65 years or older admitted to a coronary care unit in a district general hospital which serves a population of 140 000 and which practises an integrated admissions policy (10). The criteria for admission to the medical unit are based solely on whether a patient has an acute illness and not on his or her age. Patients complaining of chest pain are admitted whenever possible to a four-bedded coronary care unit which likewise has no age-linked policy for admission or thrombolysis.

Methods

Records of all patients aged 65 years or over admitted to the coronary care unit over a 12-month period between June 1990 and June 1991 were reviewed. The reason for admission was studied and particular attention paid to those patients with proven acute myocardial infarction and their subsequent management. The diagnosis of acute myocardial infarction was made initially on the basis of clinical history and electrocardiographic (ECG) evidence (ST elevation in at least two leads with or without Q waves), and later supported by creatinine phosphokinase (CPK) levels twice the upper limit of normal. Thrombolysis was induced with infusions of streptokinase 1.5 million units over 1 h or tissue plasminogen activator (tPA) 100 mg over 3 h. All patients received aspirin, 300 mg stat on admission followed by 150 mg daily, and heparin 12 500 units bd subcutaneously for 5 days or 24 000 units over 24 h intravenously for 5 days.

The reasons for not giving thrombolytic agents to patients with proven acute myocardial infarction in this age group were also analysed.

Results

During the 12-month study period 760 patients were admitted to the coronary care unit: 382 (50%) were aged 65 years or over and the reasons for their admission are summarized in Table I. In this group, 135 (35%) patients were thought to have evidence of acute myocardial infarction, 116 at initial presentation and 19 after further investigations. Of those 116 patients suspected of having an acute myocardial infarction at initial presentation, 75 (65%) received thrombolytic therapy (68 with streptokinase and seven with tpA). Their mean age was 70.5 years (SD 8.4).

Table I. Analysis of diagnosis and management of 382 patients over 65 years admitted to the Coronary Care Unit

                                              No. (%)
Suspected AMI                                 116 (30)
Received thrombolytic                75
Did not receive thrombolytic         41
Chest pain
AMI subsequently confirmed                     19 (5)
AMI not confirmed                             151 (40)
Arrhythmia                                     67 (18)
Cardiac Failure                                19 (5)
Other                                          10 (2)
Total                                         382

Table II shows the reasons why 60 patients with subsequently proven acute myocardial infarction did not receive thrombolytic agents. Delays in confirming the diagnosis accounted for 19 patients already mentioned and a further 37 patients were excluded because of supposed contra-indications. In four patients there appeared to be no valid reason for omitting thrombolytic therapy.