Mortality and risk indicators for death during five years after acute myocardial infarction among patients with and without ST elevation on admission electrocardiogram

Occurrence, characteristics, and outcome of patients hospitalized with a diagnosis of acute myocardial infarction who do not fulfill traditional criteria

BACKGROUND

The diagnosis of acute myocardial infarction (AMI) is traditionally based on clinical history, elevation of serum enzyme activity, and typical changes in the electrocardiogram (ECG); however, not all patients who develop AMI fulfill these criteria on discharge from hospital.

HYPOTHESIS

The aim of the study was to evaluate (1) the frequency with which the traditional criteria for AMI are not fulfilled among patients diagnosed with AMI on discharge, and (2) whether patients with and without these criteria differ in terms of characteristics, treatment, and outcome.

METHODS

All patients aged < 75 years and hospitalized in the municipality of Göteborg with a discharge diagnosis of AMI were included. Fulfillment criteria for AMI were two of the following three points: (1) chest pain, (2) increase in cardiac enzymes, and (3) development of Q waves.

RESULTS

In all, 1,188 admitted patients, 27% of whom were women, were included in the analysis. Of these, 193 (16%) did not fulfill the traditional criteria for AMI. These patients had an in-hospital mortality rate of 48%; of these, 59% died a sudden death, and of those who were autopsied (62%), 96% showed signs of a fresh AMI. The most common symptom on admission to hospital in patients who did not fulfill the traditional criteria was chest pain (34%), followed by dyspnea (27%) and fatigue (14%). Of those who died suddenly, fewer than half had been admitted to the coronary care unit.

CONCLUSION

Patients diagnosed with AMI who do not fulfill the traditional diagnosis criteria have high mortality. On admission to hospital, the initial suspicion of AMI is often vague. Measures for earlier detection of life-threatening coronary artery disease among these patients are warranted.

Predicting a life-threatening disease and death among ambulance-transported patients with chest pain or other symptoms raising suspicion of an acute coronary syndrome

The purpose of this study was to evaluate the possibility to predict in the prehospital phase the occurrence of a life-threatening disease or death among ambulance transported patients with acute chest pain or other symptoms raising any suspicion of an acute coronary syndrome. All patients transported by ambulance during 3 months in the community of Göteborg because of symptoms raising any suspicion of an acute coronary syndrome were included in the study. In all, 930 transports (of 859 patients) fulfilled the inclusion criteria, of which 235 (25.3%) fulfilled the criteria for a life-threatening disease. The overall 30-day mortality was 8.8%, and the 1-year mortality was 18.0%. Independent predictors for a life-threatening disease were a low oxygen saturation on admission of the ambulance crew, patient being clammy on admission of the ambulance crew, a history of myocardial infarction and ST elevation and T-wave inversion on admission to the emergency department. Independent predictors for 30-day mortality were age greater than 70 years, symptoms of dyspnoea, a low oxygen saturation, hypotension and decreased consciousness on admission of the ambulance crew, and ST-depression on electrocardiogram (ECG) on admission to the emergency department. Predictors of 1 year mortality were age greater than 70 years, a history of myocardial infarction, symptoms of dyspnoea, a low oxygen saturation on admission of the ambulance crew and ST-depression, and no sinus rhythm on admission to the emergency department. Among patients with acute chest pain or other symptoms raising any suspicion of an acute coronary syndrome, factors associated with a life-threatening disease and death could be defined. Predictors for the risk of death during the first 30 days were age greater than 70 years, symptoms of dyspnoea, a low oxygen saturation, hypotension and decreased consciousness on admission of the ambulance crew, and ST-depression on ECG on admission to the emergency department.

Influence of previous aspirin treatment and smoking on the electrocardiographic manifestations of injury in acute myocardial infarction

OBJECTIVE

To examine demographic and clinical characteristics of patients with acute myocardial infarction in order to identify factors affecting the electrocardiographic evolution of injury.

METHODS

Prospective cohort study of 1399 consecutive patients with a first myocardial infarction. Baseline clinical data associated with ST elevation and Q wave development were identified and 12 month survival was estimated.

RESULTS

Smoking had complex effects on the evolution of injury, increasing the odds of ST elevation (odds ratio (OR) 1.61; 95% confidence interval (CI) 1.08 to 2.36), but reducing the odds of Q wave development (OR 0.69, 95% CI 0.49 to 0.96). The effects of previous aspirin treatment were more consistent with reductions in the odds of ST elevation (OR 0.57, 95% CI 0.35 to 0.94) and Q wave development (OR 0.53, 95% CI 0.34 to 0. 84). ST elevation and Q wave development were both associated with an adverse prognosis, with estimated 12 month survival rates of 80. 6% (95% CI 78.2% to 83.1%) and 80.0% (95% CI 77.5% to 82.5%), respectively, compared with 86.5% (95% CI 81.2% to 91.9%) and 89.9% (95% CI 86.2% to 93.7%) for patients without these ECG changes.

CONCLUSIONS

The thrombogenicity of the blood may be a major determinant of infarct severity. Smoking increases thrombogenicity and the likelihood of ST elevation, but because coronary occlusion is relatively more thrombotic in smokers, responses to both endogenous and exogenous thrombolysis are better, reducing the risk of Q wave development. Previous aspirin treatment reduces thrombogenicity, protecting against ST elevation and Q wave development.

Overview of clinical trials of glycoprotein IIb-IIIa inhibitors in acute coronary syndromes

Acute coronary syndromes (ACS) are the major cause of mortality and morbidity in Western countries. The primary pathophysiologic mechanism of ACS involves the formation of thrombus in coronary arteries in response to spontaneous or intervention-induced endothelial damage. This leads to myocardial ischemia. The final common pathway to the coronary thrombosis underlying ACS involves the aggregation of platelets mediated by the binding of soluble fibrinogen to the platelet receptor glycoprotein (GP) IIb-IIIa. Several GP IIb-IIIa inhibitors have been developed that promise greater antithrombotic potential than aspirin and heparin alone. Over the past 2 years, 4 major trials involving more than 18,000 patients have evaluated the therapeutic potential of 3 small-molecule, intravenous GP IIb-IIIa inhibitors as a component of first-line management of unstable angina or non-ST-segment elevation myocardial infarction. Results of these studies show that administration of a GP IIb-IIIa inhibitor in combination with aspirin and heparin provides a significant reduction in mortality and morbidity rates compared with aspirin plus heparin alone. Recent approvals of 2 GP IIb-IIIa inhibitors, the peptide eptifibatide and the peptidomimetic tirofiban, mark the beginning of a new era in the management of non-ST-segment elevation ACS.