Abstract 1994: The Price of Vigilance-How Often Does a Primary Angioplasty Program Find No Flow-Limiting Coronary Artery Disease to Treat?
Background: Many hospitals have established primary angioplasty (PCI) programs with a goal of providing consistently timely reperfusion for patients with suspected acute ST segment elevation myocardial infarction (STEMI). As the locus of control for activation of the cardiac catheterization laboratory moves from the cardiologist to the emergency department (ED) and even to pre-hospital activation by emergency medical services, concerns have been raised about “false positive” activations of the primary angioplasty team.
Objective and Methods: We reviewed data from the cardiac catheterization laboratory database at a large, urban, academic medical center with an around-the-clock primary angioplasty program to determine how often flow-limiting coronary artery disease (CAD) was NOT found among patients undergoing emergent cardiac catheterization for suspected acute MI.
Results: From 4/04–5/07, expedited coronary angiography was performed for 593 patients with suspected acute left bundle branch block (LBBB), posterior, or STE-MI (representing 68% of emergent or salvage cardiac catheterizations during that time). No lesions of ≥50% diameter stenoses in the major epicardial coronary arteries were found in 37 patients. Of these, 3 underwent PCI nonetheless (2 for thrombotic 40% lesions, 1 for spontaneous circumflex dissection); 17 had focal or regional left ventricular systolic dysfunction, 14 had normal systolic function; 10 patients had elevated troponin-T and 5 had abnormal CK-MB. The prevalence of “no CAD” did not differ by patient source (6.9% for ED patients, 6.7% for inpatients, 5.8% for transfers), but was higher among those with LBBB (25%) vs. STE (5.9%) or posterior MI (0%); p=0.03. Among those with CAD, 93.3% underwent revascularization.
Conclusions: Among patients undergoing expedited coronary angiography for suspected acute MI, 2.0% had no angiographically-apparent CAD, normal wall motion, and normal biomarkers; 6.2% had CAD not warranting PCI or bypass surgery; and 5.4% had no CAD but elevated biomarkers or abnormal systolic function. Our current strategy for activating the primary PCI team resulted in few truly “false positive” procedures, although mimics of STEMI with demonstrable cardiac abnormalities were not infrequent.