Predictors of risk in patients with unstable angina admitted to a district general hospital

Abstract

Objective: To observe the long-term prognosis of patients with unstable angina and select simple criteria to identify high and low risk subgroups.

Design: A six month prospective survey with three year follow up.

Setting: One eleven bed coronary care unit.

Patients: All patients admitted with chest pain in whom no infarct was confirmed by subsequent electrocardiographic or enzyme changes and for whom no alternative cause of chest pain was found were studied. Unstable angina was also diagnosed if there was evidence of myocardial ischaemia in the form of previous effort angina, previous myocardial infarction, or if transient electrocardiographic changes accompanied the pain. When none of the above were present, chest pain without a known cause, was diagnosed.

Interventions: No routine intervention. Angiography and revascularisation for persistent symptoms despite medical treatment.

Outcome measures: Death or non-fatal infarction.

Results: In the 141 patients with unstable angina there were eight deaths and five non-fatal infarctions during the first eight weeks. Symptoms of increasing angina before admission were similar in all three groups and did not help predict early complications. Recurrence of pain in hospital, a rise in cardiac enzymes to less than twice the upper limit of normal, and transient electrocardiographic changes were all associated with an increased risk of early events. The presence of either abnormal enzyme activity or more than five episodes of pain in hospital identified a group of 49 in whom 11 of the 13 early events occurred. After three years, 29 of the 141 patients had died and eight had had infarctions (overall event rate 26%). Seventeen had undergone revascularisation (12%) and 51 (36%) were on antianginal treatment. Thirty six (26%) were still alive, without new myocardial infarction, and were free of angina. In the 29 patients with chest pain without a known cause there were no early events and only one non-fatal infarction during the three year follow up.

Conclusion: When patients are admitted to the coronary care unit with chest pain not due to myocardial infarction, the history, electrocardiography and measurement of cardiac enzymes are sufficient to identify high and low risk subgroups.