Clinical investigations
Prediction of missed myocardial infarction among symptomatic outpatients without coronary heart disease

https://doi.org/10.1016/j.ahj.2004.06.014Get rights and content

Abstract

Background

Missed diagnoses of acute myocardial infarction (AMI) in the ambulatory setting can cause patient suffering and malpractice litigation. Multiple algorithms have been developed to detect the presence of coronary heart disease (CHD) or acute coronary ischemia.

Methods

We performed a case-control study of patients with no prior history of CHD presenting to outpatient practices with potential cardiac ischemia. Malpractice claims files were used to identify 18 cases of patients with missed AMIs. For each case, we identified 3 control patients who had office visits for chest pain during the same month and assessed the association of 4 different prediction tools with missed AMI.

Results

The 18 cases of missed AMI had a 39% 1-month mortality rate. Cases were more likely than controls to be men (67% vs 26%, P = .001), to be smokers (88% vs 39%, P < .001), and to have low HDL cholesterol (39 mg/dL vs 59 mg/dL, P < .001) and elevated total cholesterol (236 mg/dL vs 213 mg/dL, P = .01). A Framingham risk score predicting a 10-year risk of CHD ≥10% and a positive score using the Goldman risk predictor were associated with an increased risk of missed AMI (odds ratio 5.7, 95% CI 1.8–18.4 for Framingham risk score; odds ratio 7.2, 95% CI 1.4–36.8 for Goldman risk predictor).

Conclusions

Among ambulatory patients with possible cardiac ischemia and no prior CHD, multiple algorithms may be useful for improvement of risk stratification.

Section snippets

Study design

We performed a retrospective case-control study of patients with no previous history of CHD presenting to primary care physician practices with potential cardiac ischemia. Cases of missed myocardial infarction were identified from the malpractice claims files of the Controlled Risk Insurance Company (CRICO), which provides medical malpractice coverage for approximately 8000 physicians at Harvard University–affiliated clinical institutions. Missed diagnoses of myocardial infarction were found

Results

The 18 identified cases of missed myocardial infarction occurred in a variety of ambulatory settings including academic centers (n = 2, 11%), community practices (n = 8, 44%), and clinics affiliated with a large health maintenance organization (n = 8, 44%). Table Ishows the distribution of cardiac risk factors among the cases and matched controls. Patients in both groups were relatively young (mean ages: 50 years and 47 years). Cases were more likely to be men (67% vs 26%, P = .001), smokers

Discussion

We studied symptomatic patients with no previous history of CHD who experienced missed myocardial infarctions in the ambulatory setting and found that they were more likely than matched controls to have an elevated Diamond and Forrester probability of CHD and an elevated FRS. The association appears to be stronger with the FRS model than with the Diamond and Forrester model, as patients experienced a 12% increase in occurrence of missed MI for every 1% increase in FRS versus only a 3% increase

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This work was supported by a grant from the Risk Management Foundation of the Harvard Medical Institutions. The authors had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

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