Black Patients With Chest Pain Differ From Whites, but Risks Are Similar
An analysis of PROMISE teases out differences in baseline factors and imaging evidence of CAD, but explanations are lacking.
Black patients undergoing noninvasive testing for chest pain have a higher burden of cardiovascular disease risk factors than white patients, but both have a similarly low risk of major adverse cardiovascular events over 2 years, according to an analysis of the PROMISE trial.
Interestingly, Black patients, despite having more risk factors such as diabetes and hypertension, were less likely than white patients to have evidence of CAD—such as coronary artery calcium (CAC), significant coronary stenoses, and high-risk atherosclerotic plaque—on coronary computed tomography angiography (CCTA).
Lead investigator Lili Zhang, MD, ScM (Montefiore Medical Center, New York), said the reason why Black patients have a higher burden of CVD risk factors but less epicardial CAD is not well understood. “A potential explanation is that Black individuals may have more microvascular disease as a result of their higher risk burden, but microvascular disease is not assessed by CCTA,” she told TCTMD.
Originally presented and published in 2015, the PROMISE trial randomized 10,003 patients with new-onset chest pain to a strategy of anatomical testing with CCTA or to functional testing, such as exercise ECG, nuclear stress testing, or stress echocardiography. Over a median follow-up of 2 years, CCTA did not improve clinical outcomes. As a pragmatic trial, PROMISE included a broad patient population treated across a range of practices, including academic medical centers. In total, 12.2% of patients randomized were Black, which roughly corresponds to the same percentage in the US population overall.
“It’s a slightly more modern population than some of the comparisons done between Black and white persons in other studies,” senior investigator Michael Lu, MD, MPH (Massachusetts General Hospital, Boston), told TCTMD.
In terms of risk factors, Black subjects had significantly greater body mass index and more hypertension, diabetes, and metabolic syndrome than white patients. They were also more likely to have a sedentary lifestyle. The mean number of CVD risk factors per patient was 2.47 in Black participants versus 2.35 in white subjects (P < 0.001). Black participants also had a significantly higher 10-year ASCVD risk score.
Overall, the MACE rate occurred in 3.1% of the PROMISE population after 2 years, but there was no significant difference between races (3.0% in Black vs 3.2% in white subjects; P = 0.84). On multivariate modeling, which adjusted for baseline risk factors, there was again no statistically significant difference in MACE between the groups.
In the cohort undergoing CCTA, 54.9% of Black patients had a CAC score of zero compared with 36.8% of white subjects. Black subjects were also less likely to have a CAC score greater than 400 (8.1% vs 14.4% in white patients; P = 0.001). Similarly, just 8.7% of Black patients had a coronary stenosis ≥ 50% compared with 14.6% of white patients (P = 0.001). Additionally, features of high-risk plaque, such as positive remodeling or low CT attenuation, among others, were less common in Black than in white patients (37.6% vs 52.4%; P < 0.001).
In terms of why Black subjects had less CAD on CCTA despite their higher risk burden, Lu, like Zhang, said it’s possible that the imaging modality simply isn’t picking up the full extent of heart disease. “There is the disease you can see on coronary CT—the so-called epicardial coronary artery disease, which is the big arteries you can see and put stents in—but there’s also microvascular disease in the small arteries that can’t be seen with CT,” he said.
Investigators aren’t exactly sure why there is a disconnect between risk factor burden and evidence of CAD on CCTA. Lu emphasized that while Black subjects might be less likely to have CAD, the association between CCTA features—coronary stenosis, CAC, and high-risk plaque—were associated with a similar risk of MACE in both races.
“There were some differences [between Black and white subjects], but in fact, there were a lot of similarities,” he told TCTMD. “In both groups, very few patients coming in with stable chest pain had an adverse cardiac event. The event rate was similar between Black and white persons. In both groups, the amount of plaque in the coronary arteries was very predictive of having those cardiac events. Whether you’re Black or white, the more plaque you have, the worse the outcome.”
The new 2021 American College of Cardiology/American Heart Association (ACC/AHA) guidelines for the evaluation of chest pain in intermediate-to-high risk patients recently made CCTA a class I indication.
This will inevitably lead to more use of the technology in both Black and white patients, the authors note, a situation which makes knowledge of the potentially different findings—and their implications for care—all the more important.
“This incongruous situation in which Black individuals had more cardiovascular risk factors, yet less coronary plaque on CCTA and similar 2-year MACE, underscores the limits of our understanding of the relationship between risk factors and plaque in Black and White persons.”
Zhang L, Olalere D, Mayrhofer T, et al. Differences in cardiovascular risk, coronary artery disease, and cardiac events between Black and white individuals enrolled in the PROMISE trial. JAMA Cardiol. 2021. Epub ahead of print.
- Lu reports grants from AstraZeneca, MedImmune, and Kowa and consulting fees from PQBypass.
- Zhang reports no conflicts of interest.