Risk stratification after acute myocardial infarction by Doppler stroke distance measurement

Abstract

Objective: To establish the value of Doppler stroke distance measurement as a predictor of mortality risk following acute myocardial infarction.

Design: Follow up study.

Setting: Coronary care unit of a teaching and district general hospital.

Subjects: 378 patients (mean age 61 years) with acute myocardial infarction followed up for a mean of five years (range 2-7 years); 299 (79%) patients received thrombolysis.

Main outcome measures: Stroke distance (the systolic velocity integral of blood flow in the aortic arch (percentage of age predicted normal value)); presence or absence of left ventricular failure on the admission chest radiograph; the codified admission ECG; death during follow up.

Results: Mean (SD) stroke distance was 81 (19)% and five year survival 76%. For patients with stroke distance > 100% (n = 60), 82-100% (n = 134), 63-81% (n = 122), and < 63% (n = 62), the one month mortality rates were 0%, 1.5%, 4%, and 18%, respectively; the corresponding estimates for mortality at five years were 17%, 19%, 24%, and 43%. Survival was independently related to age (p < 0.0001), stroke distance (p < 0.0001), and chest radiograph appearance (p = 0.002), but not to ECG codes (p = 0.31) or receipt of thrombolysis (p = 0.60). The areas under receiver operator characteristic plots for stroke distance measurements were 82%, 76%, 71%, and 65% for deaths within one month, six months, one year, and two years, respectively.

Conclusions: The bedside measurement of stroke distance stratifies mortality risk after acute myocardial infarction. The predictive ability of this simple measure of left ventricular systolic function compares well with published accounts of the more complex measurement of ejection fraction.

Figure 1

Graphs of logistic regression equation relating probability of death within one month to stroke distance, with and without a normal chest radiograph.

Figure 2

Survival curves for all patients (mean stroke distance 81%), and for those with stroke distance > 100% and < 63%.

Figure 3

Survival curves for all patients, and for those with or without a normal chest radiograph on admission.

Figure 4

ROC curves for the prediction of death within one month, six months, one year, and two years for various values of stroke distance. Inflections of the curves for stroke distances of 60%, 70%, and 80% are indicated.