Validation of a clinical prediction rule for a preserved left ventricular systolic function in patients after Myocardial Infarction.

Background: LV systolic function is the single most important predictor of mortality following myocardial infarction. Several indicators of LV dysfunction such as non-invasive estimations of Ejection Fraction (EF) like echocardioqraphy have been examined for prognostic implication. Several studies have yielded clinical predictors of LVEF which were either difficult to use at bedside, have substantial mis-classification rates or have never been validated for easy use. This study was conducted to validate the Silver Criteria for a preserved Left Ventricular systolic function in patients after myocardial infarction and adopt a clinical prediction rule that is reliable & applicable to our local setting.

Methods: This is a validation study involving 108 patients admitted at the Philippine Heart Center from April 2005 to April 2006 due to Acute Myocardial Infarction. Clinical and radiologic evidences of congestive heart failure were noted. Electrocardiographic recordings were reviewed and classified as interpretable or uninterpretable based on the Silver Criteria. Echocardiographic determination of LV EF was done and was compared to the Silver clinical criteria, which consists of 4 clinical parameters. Validity measures, such as sensitivity, specificity, PPV and NPV were then determined.

Results: In the group with predicted EF to be at least 40% (n=34), the most common location of infarction was inferior wall and all patients (100%) had an-actual EF of at least 40%. Whereas in the group with unpredictable EF (n=74), 41% had an EF between 40-54%, 34% had EF <40% and 25% above 55%. The Positive Predictive Value (PPV) of this prediction rule was 100% while its Negative Predictive Value (NPV) was 34 %. The sensitivity was 41% while the specificity was 42%.

Conclusion: This simple yet reliable clinical prediction rule (Silver Criteria) for a preserved LV systolic function for post MI patients is of great value in the management of such patients especially when limited medical resources is a major concern.