Abstract 4143615: Does the Prognostic Value of Zero Coronary Artery Calcium Score Vary by Patient Sex?

Background: A coronary artery calcium score of zero (CAC=0) is generally accepted as a marker of a very low 5y risk for coronary events. However, whether the prognostic value of CAC=0 varies by sex is unclear. For example, non-atherosclerotic causes of coronary ischemia present more often in women, including spontaneous coronary artery dissection and microvascular angina, which may be undetected by CAC. Further, CAC is performed at a later age in women. Whether these factors impact the utility of CAC=0 in women vs men is uncertain. Methods: We tested whether the prognostic value of CAC=0 differs by sex. We searched the Intermountain Health electronic medical record (eMR) database for patients (pts) at primary coronary risk who underwent positron emission tomography/computed tomography (PET/CT) stress testing and had a zero CAC score. We assessed coronary prognosis (i.e., coronary death [CD] or non-fatal myocardial infarction [MI]) during follow-up. Primary events were adjudicated by chart review. We compared outcomes in women vs. men. Given the small number of events, chi-square rather than time-to-event analyses were performed. We also compared all-cause death or MI rates in those with CAC=0 vs. CAC>0 by sex. Results: The eMR search identified19,495 women and 20,523 men undergoing PET/CT who were at primary coronary risk. Of these, 7967 (19.9%) had CAC=0 on CT. Of CAC=0 patients, 5400 (67.8%) were women and 2567 (32.2%) were men. Overall age averaged 60.5y (SD 12.0) in women and 53.8y (SD 12.6) in men. In total, 13 events occurred (MI=12, CD=1) over a follow-up of 2.1y (SD 1.6). By sex, 7 events (0.13%) occurred in CAC=0 women and 6 (0.24%) in men (p=0.28). Rates of all-cause death or non-fatal MI comparing CAC=0 to CAC>0 were 3.3% vs 9.5% in women and 3.3% vs 10.2% in men (both p<.0001). MI with no obstructive coronary artery disease (MINOCA) constituted 3/7 MI’s in women and 1/5 MI’s in men. Conclusions: In this large, integrated healthcare system experience of symptomatic pts at primary coronary risk undergoing PET/CT, a zero CAC score predicted an excellent prognosis for coronary death or non-fatal MI in both sexes. CAC=0 was more frequently observed in women despite an older average age. Rates of coronary events were at least as low in women as in men, with a trend to more MINOCA events and fewer obstructive coronary events in women. Further, a zero calcified plaque burden predicted a 3-fold lower risk of all-cause death or MI in both sexes.