Prognostic value of biochemical markers, 12-lead ECG and patient characteristics amongst patients calling for an ambulance due to a suspected acute coronary syndrome

Authors


Dr Leif Svensson, Division of Cardiology, South Hospital, SE-118 83 Stockholm, Sweden (fax: +46-8-6163040; e-mail: leif.svensson@sos.sll.se).

Abstract.

Objectives.  To evaluate whether a 12-lead ECG, together with a multi-marker strategy that used point-of-care measurements of myoglobin, creatine kinase (CK-MB) and troponin I, was able to predict patients at short- and long-term risk of death, when simultaneously considering age, gender, previous history, symptoms and clinical findings on arrival of the ambulance.

Design.  Prospective observational study.

Setting and subjects.  Consecutive patients (n=511) in ambulances in Stockholm and Göteborg in Sweden who called for an ambulance due to chest pain or other symptoms raising a suspicion of acute coronary syndrome.

Intervention.  In almost all patients, a diagnostic ECG, patient baseline characteristics and measurements of CK-MB, troponin I and myoglobin were recorded.

Results.  In univariate analysis, the highest 30-day mortality (17%) was found amongst patients with the combination of ECG signs of myocardial ischaemia and the elevation of any biochemical marker. The highest 1-year mortality (20%) was found amongst patients with ECG signs of myocardial ischaemia and the elevation of any biochemical marker. Increasing age (RR 1.07; 95 CI 1.02–1.13) lack of symptoms of chest pain and a previous history of hypertension (3.02; 1.08–8.79) were independent predictors of 30-day mortality. Myoglobin was the only biochemical marker independently associated with 30-day mortality (6.66; 1.83–22.3). Increasing age (1.11; 1.06–1.16), previous history of diabetes (3.42; 1.41–8.25) heart failure (2.64; 1.26–5.52) and other symptoms than chest pain and dyspnoea (5.23; 2.14–12.76) were independent predictors of 1-year mortality. In many of the variables the confidence limits were wide.

Conclusion.  Amongst patients with a clinical suspicion of acute coronary syndrome, those with the combination of ECG signs of myocardial ischaemia and the elevation of any biochemical marker on arrival of the ambulance form a group with a particularly high risk of death. However, age as well as aspects of clinical history and type of symptoms independently contribute to prognostic information.

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