Prevalence and Factors Associated With False-Positive ST-Segment Elevation Myocardial Infarction Diagnoses at Primary Percutaneous Coronary Intervention–Capable Centers

Abstract

Background Rapid activation of the cardiac catheterization laboratory for primary percutaneous coronary intervention (PCI) improves outcomes for ST-segment elevation myocardial infarction (STEMI), but selected emphasis on minimizing time to reperfusion may lead to a greater frequency of false-positive activations.

Methods We analyzed consecutive patients referred for primary PCI for a possible STEMI at 2 centers from October 2008 to April 2011. “False-positive STEMI activation” was defined as lack of a culprit lesion by angiography or by assessment of clinical, electrocardiographic, and biomarker data in the absence of angiography. Clinical and electrocardiographic factors associated with false-positive activations were evaluated in a backward stepwise selection bootstrapped logistic regression model.

Results Of 411 STEMI activations by emergency physicians, 146 (36%) were deemed to be false-positive activations. Structural heart disease and heart failure were the most common diagnoses among false-positive activations. Electrocardiographic left ventricular hypertrophy (adjusted odds ratio [AOR], 3.15; 95% CI, 1.55-6.40; P = .001), a history of coronary disease (AOR, 1.93; 95% CI, 1.04-3.59; P = .04), or prior illicit drug abuse (AOR, 2.67; 95% CI, 1.13-6.26; P = .02) independently increased the odds of false-positive STEMI activations. Increasing body mass index decreased the odds of a false-positive activation (AOR, 0.91; 95% CI, 0.86-0.97; P = .004), as did angina at presentation (AOR, 0.28; 95% CI, 0.14-0.57; P < .001).

Conclusions More than a third of patients referred for primary PCI from the emergency department did not have a STEMI. Multiple patient-level characteristics were significantly associated with an increased odds of false-positive STEMI activation.

Reperfusion therapy with percutaneous coronary intervention (PCI) is recommended for treatment of ST-segment elevation myocardial infarction (STEMI) when readily available.1 One strategy that was found to facilitate a more rapid administration of PCI is autonomous STEMI team activation by emergency department (ED) physicians without routine cardiology consultation.2- 7

Appropriate STEMI care and national health care quality metrics emphasize the timeliness of reperfusion therapy, but patient safety and health care costs demand thoughtful and judicious implementation of emergency coronary angiography. Nevertheless, inaccurate STEMI diagnoses with so-called false-positive activations of the cardiac catheterization team for emergent cardiac angiography are not only anticipated, they are readily accepted in an effort to preferentially emphasize diagnostic sensitivity. However, acceptable rates of false-positive activations are not established. Furthermore, current STEMI diagnosis accuracy remains uncertain owing to discrepancies in defining a false-positive STEMI diagnosis,8,9 temporal trends in primary PCI availability at nontertiary care centers,10,11 and potential reclassification bias within national angiographically based STEMI registries.

The objective of this study was to determine the prevalence of false-positive STEMI diagnoses among emergency physicians at primary PCI-capable centers. We also assessed the relationship between false-positive activations and clinical and electrocardiographic (ECG) factors available at the time of diagnosis.