This study retrospectively evaluated a university-based CDP to determine sex-based differences in risk stratification, non-invasive or invasive workups, and 30-day MACE. We found no sex-based differences when HEART score was used for risk stratification. Moreover, we found similar rates of non-invasive testing across all risk categories, even when stratified by sex. However, high-risk males underwent comparatively higher rates of coronary angiogram/PCI, and consequently had higher overall MACE than females at 30-days.
Our study is unique in that we found no differences in risk stratification between males and females, but also in the breakdown of low, intermediate, and high-risk patients. This contradicts other studies that have found that females are inappropriately stratified into lower risk categories [2, 7]. Compared to these studies, we risk-stratified patients as more high-risk. This may have been a ramification of our institutions high-sensitivity assays and sex-specific troponin thresholds, which may have improved sensitivity compared to the contemporary assays used in the other trials [4, 8].
We also identified no differences in non-invasive testing between males and females of all risk categories. This contradicts other studies that have demonstrated disparate testing rates [1, 9]. Interestingly, our study showed very low testing rates for low-risk patients when the CDP was used. This illustrates the utility in CDPs for promoting early discharge and minimizing unnecessary testing. Moreover, a structured and selective approach to testing may reduce downstream interventions without increased acute myocardial infarction [10]. There were otherwise similar ordering patterns for coronary CTAs amongst all risk-categories, but more stress testing in the high-risk category. Current sub-testing recommendations suggest use of coronary CTA in appropriate patients, but exclusion criteria were often met in this population, including previous PCI or CABG, reduced renal function, elevated BMI, irregular heart rhythm, and local preference for functional testing. While there is some data to suggest coronary CTAs may hasten early discharge [11], there is other data to suggest that coronary CTAs lead to more invasive cardiac procedures compared to stress testing [12] without any changes in all-cause mortality. More research is needed to see how these tests differ based on underlying risk categorization.
Review of invasive testing and intervention rates indicate high-risk males undergo comparatively more procedures. There were two instances of coronary angiogram in low-risk males in our review, one of which resulted in PCI. The first patient developed chest pain with syncope and ST-elevations thought to be due to early repolarization. This patient did not develop any troponin elevations greater than the URL, nor did they have any angiographically significant stenoses on coronary angiogram. The second patient had past medical history of STEMI treated with PCI to the LAD. He represented two years later for syncope with brief chest pressure. ECG was normal on admission. He was taken to the catheterization lab due to up-trending troponins where he was found to have non-occlusive thrombus adjacent to his proximal LAD stent. He required repeat stent placement to the proximal LAD. Excluding these two patients, the connection between high-risk males and increased rate of invasive procedures/interventions may be explained by the underlying physiology leading to patient presentation. One study showed that males had more non-culprit lesions by angiography and IVUS, as well as a higher incidence of plaque rupture (16.3% vs 6.6%, p = 0.002) [13]. This was thought to be due in part to plaque structure, where females had less necrotic cores. On the other hand, females demonstrated high rates of microvascular dysfunction and spontaneous coronary artery dissection, which are not necessarily as amenable to PCI [1]. It should be noted that the HEART score is meant to risk stratify patients for ACS, which is not necessarily the same metric as stratifying patients who would benefit from invasive imaging or interventions. This could explain the discordance between invasive testing/interventions rates in high-risk patients.
In conclusion, our retrospective analysis showed no differences in risk stratification or non-invasive testing between males and females when the CDP was used. High risk males, however, underwent more coronary angiogram and PCI than high risk females, and consequently males experienced more overall MACE than females. This disparity may be explained by sex-based differences in the pathophysiology driving each patient’s presentation. Future work will examine different iterations of the CDP to elucidate how these sex-disparities are being mitigated.