A previous study showed that patients with previous myocardial infarction (MI) who meet 4 simple clinical and/or electrocardiographic criteria have a left ventricular ejection fraction (LVEF) of 40% or greater, with a positive predictive value of 98%. The objective of this study was to validate this clinical rule in the community hospital setting.
Retrospective chart review in a 330-bed community hospital. Two hundred thirteen consecutive patients with MI were identified between June 1, 1993, and March 31, 1995. Left ventricular ejection fraction was predicted in a blinded fashion by means of the clinical rule before the actual LVEF test was reviewed.
We identified 213 patients admitted with the primary discharge diagnosis of acute MI. All patients met standard clinical and enzymatic definitions for acute MI and had at least 1 measure of LVEF, such as echocardiography, ventricular angiography, or gated blood pool scan. The clinical rule predicted that 83 patients (39.0%) would have an LVEF of 40% or greater. Of these 83 patients, 71 had an ejection fraction of 40% or greater, for a positive predictive value of 86%. Of the 12 patients who were incorrectly predicted to have a preserved LVEF, 6 (50%) had an index non–Q-wave anterior MI (P<.001). Reanalyzing the patient population with a fifth variable (anterior non–Q-wave MI) added to the original 4 variables increased the positive predictive value to 91%.
This simple clinical prediction rule has a positive predictive value of 86% when applied in the community hospital setting. Patients with anterior non–Q-wave MI may be 1 group in whom the rule is inaccurate, and expanding the clinical rule to 5 variables may increase the positive predictive value. When a technology-based assessment of left ventricular function is considered in patients after an MI, this prediction rule may allow for a more cost-effective patient selection, and as many as 40% of patients who have had acute MIs may require no testing at all.