Abstract 18075: Prevalence and Predictors of the Absence of Obstructive Epicardial Coronary Artery Disease in Patients Referred for Index Coronary Angiography

Background: As many as 62.4% of patients undergoing elective coronary angiography have no obstructive epicardial coronary artery disease (CAD). These patients have substantial morbidity and are inadequately characterized. Our aim was to identify the prevalence and predictors of the absence of epicardial obstructive CAD and to assess the clinical characteristics of this population. Methods: We conducted a retrospective analysis of consecutive patients undergoing index coronary angiography. Patients with known CAD, a history of myocardial infarction, or an emergent indication were excluded, as were those evaluated for transplantation or valvular/cardiac surgery. Obstructive CAD was defined as a stenosis ≥70% (≥50% left main). We performed multivariable logistic regression of clinical variables, peak troponin levels, and stress findings to identify predictors of the absence of obstructive epicardial CAD. Results: The study population included 935 patients with median age of 62 years and 10-year ASCVD risk score of 17.7%; 55.6% of the patients were male, 35.1% had diabetes, 77.3% had hypertension, and 67.8% had hyperlipidemia. No obstructive CAD was found in 442 patients (47.3%). Ten variables were independent predictors of the absence of obstructive CAD in a multivariable analysis (Table 1). In the 258 patients who underwent stress imaging, a negative stress ECG (OR 3.1 (1.6-6.0), p<0.001) and absence of ischemia on stress imaging (OR 3.6 (1.9-6.8), p<0.001) were additional independent predictors. Conclusion: Despite a cohort with substantial cardiac risk factors and an intermediate median ASCVD risk score, the prevalence of index angiograms without obstructive epicardial CAD was high. Traditional markers of disease were predictors, including positive troponin and stress imaging; however the model was only 78% predictive. Additional research is needed to better characterize patients referred for catheterization without obstructive CAD.

Abstract 17488: Effect of Cocaine on Coronary Microvasculature

Background: Presence of coronary microvascular dysfunction despite normal epicardial coronary arteries is known to significantly impact mortality and morbidity. With the increasing number of cocaine users among urban population, it is imperative to assess its effect on the coronary microvasculature. Method: In this blinded, retrospective study, microvascular dysfunction was assessed using corrected Thrombolysis In Myocardial Infarction (TIMI) frame count (cTFC) and TIMI perfusion grade (TMPG), in an available consecutive series of 202 cocaine users in the absence of acute or recent MI, significant epicardial coronary artery disease (CAD) or vasospasm, among the 775 cocaine users who underwent coronary angiography at Mount Sinai Hospital, Chicago from 2005 to 2013. Applying the same criteria, the cTFCs and TMPGs were then compared with 210 randomly chosen non-cocaine users. Angiographers were blinded when determining the cTFC and TMPG. Results: The TMPG 0/1 for the left anterior descending (LAD), circumflex (LCx), and right coronary (RCA) arteries were statistically significant among cocaine users (LAD 22% versus 5%, p=<0.0001; LCx 25% versus 6%, p=<0.0001; RCA 42% versus 8%, p=<0.0001). For the cTFC, the LAD and LCx were significantly elevated among cocaine users (27.33 ± 10.9 versus 24.88 ± 10.05, p=0.03 and 41.11 ± 14.28 versus 38.23 ± 12.69, p=0.04; respectively). Additionally, there was a significant percentage of cocaine users with cTFC<14 (i.e. faster flow) observed in the RCA (9% versus 3%; p=0.008). Conclusion: Our study concludes that there is significant coronary microvascular dysfunction associated with cocaine use despite the absence of significant epicardial CAD. Additionally, reduced coronary filling time might be the reason for the observed higher frequency of hyperemic flow in the RCA among cocaine users, which is associated with poorer clinical outcomes, particularly in the context of impaired myocardial perfusion.