Atherosclerosis imaging in multiple vascular beds--enough heterogeneity to improve risk prediction?

Extra-coronary Calcification and Cardiovascular Events: What Do We Know and Where Are We Heading?

PURPOSE OF REVIEW

The coronary artery calcium score is a guideline-endorsed aid for further risk stratification in the primary prevention of atherosclerotic cardiovascular disease. The non-contrast scan performed for detection of coronary artery calcium also gives an opportunity to visualize calcifications in the thoracic aorta and in the heart valves, at no additional cost or radiation exposure. The purpose of this review was to discuss the potential clinical value of measuring thoracic aortic calcification, aortic valve calcification, and mitral annulus calcification.

RECENT FINDINGS

After two decades of active research, all three calcifications have been extensively evaluated, across various cohorts. We discuss classic and recent studies, current knowledge gaps, and future directions in this space. The added value of these measurements has traditionally been considered modest at best, and they are not currently discussed in relevant primary prevention guidelines in North America and Europe. However, recent studies evaluating high thoracic calcification thresholds and younger populations have further enriched this space. Specifically, some studies suggest that detection of severe thoracic aortic calcification may be helpful in further risk assessment and that detection of aortic valve calcifications may have important prognostic implications in younger individuals. Although more research is needed, particularly in larger young-to-middle-aged cohorts, future guidelines might consider including these features as risk-enhancing factors.

Hepatocyte growth factor is associated with greater risk of extracoronary calcification: results from the multiethnic study of atherosclerosis

BACKGROUND

Hepatocyte growth factor (HGF) is a biomarker with potential for use in the diagnosis, treatment and prognostication of cardiovascular disease (CVD). Elevated HGF is associated with calcification in the coronary arteries. However, knowledge is limited on the role HGF may play in extracoronary calcification (ECC). This study examined whether HGF is associated with ECC in the aortic valve (AVC), mitral annulus (MAC), ascending thoracic aorta and descending thoracic aortic (DTAC).

METHODS

At baseline, adults aged 45-84 years, free of CVD, in the Multi-Ethnic Study of Atherosclerosis had HGF and ECC measured by ELISA and cardiac CT scan, respectively. ECC measurements were repeated after an average of 2.4 years of follow-up. Prevalent ECC was defined as Agatston score >0 at baseline. Incident ECC was defined as Agatston score >0 at follow-up among participants with Agatston score=0 at baseline. We used Poisson and linear mixed-effects regression models to estimate the association between HGF and ECC, adjusted for sociodemographic and CVD risk factors.

RESULTS

Of 6648 participants, 53% were women. Mean (SD) age was 62 (10) years. Median (IQR) of HGF was 905 (757-1087) pg/mL. After adjustment for CVD risk factors, the highest HGF levels (tertile 3) were associated with greater prevalence and extent of AVC, MAC and DTAC at baseline compared with the lowest tertile (tertile 1). Additionally, the risk of incident AVC and MAC increased by 62% and 45%, respectively, in demographic-adjusted models. However, the associations were not statistically significant in fully adjusted models. The highest HGF levels were also associated with 10% and 13% increase in MAC and DTAC progression, respectively, even after adjustment for CVD risk factors.

CONCLUSION

Higher HGF levels were significantly associated with a greater risk of calcification at some extracoronary sites, suggesting an alternate biological pathway that could be targeted to reduce CVD risk.

Favorable Cardiovascular Health Is Associated With Lower Prevalence, Incidence, Extent, and Progression of Extracoronary Calcification: MESA

BACKGROUND

Ideal cardiovascular health (CVH) is associated with a lower incidence of cardiovascular disease. Extracoronary calcification (ECC)-measured at the aortic valve, mitral annulus, ascending thoracic aorta, and descending thoracic aorta-is an indicator of systemic atherosclerosis. This study examined whether favorable CVH was associated with a lower risk of ECC.

METHODS

We analyzed data from MESA (Multi-Ethnic Study of Atherosclerosis) participants aged 45 to 84 years without cardiovascular disease at baseline. ECC was measured by noncontrast cardiac computed tomography scan at baseline and after an average of 2.4 years. Prevalent ECC was defined as an Agatston score >0 at the baseline scan. Incident ECC was defined as Agatston score >0 at the follow-up scan among participants with Agatston score of 0 at the baseline scan. Each CVH metric (smoking, physical activity, body mass index, diet, blood pressure, total cholesterol, and blood glucose) was scored 0 to 2 points, with 2 indicating ideal; 1, intermediate; and 0, poor. The aggregated CVH score was 0 to 14 points (0-8, inadequate; 9-10, average; 11-14, optimal). We used Poisson and linear mixed-effects regression models to examine the association between CVH and ECC adjusted for sociodemographic factors.

RESULTS

Of 6504 participants, 53% were women with a mean age (SD) of 62 (10) years. Optimal and average CVH scores were associated with lower ECC prevalence, incidence, and extent. For example, optimal CVH scores were associated with 57%, 56%, 70%, and 54% lower risk of incident aortic valve calcification, mitral annulus calcification, ascending thoracic aorta calcification, and descending thoracic aorta calcification, respectively. In addition, optimal and average CVH scores were associated with lower ECC progression at 2 years, although these associations were only significant for mitral annulus calcification and descending thoracic aorta calcification.

CONCLUSIONS

In this multiethnic cohort, favorable CVH was associated with a lower risk of extracoronary atherosclerosis. These findings emphasize the importance of primordial prevention as an intervention to reduce the burden of cardiovascular disease.

Epidemiological Research Advances in Vascular Calcification in Diabetes

Vascular calcification is the transformation of arterial wall mesenchymal cells, particularly smooth muscle cells (SMCs), into osteoblast phenotypes by various pathological factors. Additionally, vascular transformation mediates the abnormal deposition of calcium salts in the vascular wall, such as intimal and media calcification. Various pathological types have been described, such as calcification and valve calcification. The incidence of vascular calcification in patients with diabetes is much higher than that in nondiabetic patients, representing a critical cause of cardiovascular events in patients with diabetes. Because basic research on the clinical transformation of vascular calcification has yet to be conducted, this study systematically expounds on the risk factors for vascular calcification, vascular bed differences, sex differences, ethnic differences, diagnosis, severity assessments, and treatments to facilitate the identification of a new entry point for basic research and subsequent clinical transformation regarding vascular calcification and corresponding clinical evaluation strategies.

Multisite extracoronary calcification indicates increased risk of coronary heart disease and all-cause mortality: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Cardiovascular calcification outside of the coronary tree, known as extracoronary calcification (ECC), is highly prevalent, often occurs concurrently in multiple sites, and yet its prognostic value is unclear.

OBJECTIVE

To determine whether multisite ECC is associated with coronary heart disease (CHD) events, CHD mortality, and all-cause mortality.

METHODS

We evaluated 5903 participants from the Multi-Ethnic Study of Atherosclerosis without diabetes who underwent CT imaging for calcification of the aortic valve, aortic root, mitral valve, and thoracic aorta. Participants were followed for 10.3 years. Multivariable adjusted hazard ratios estimated risk of outcomes for increasing numbers of ECC sites (0, 1, 2, 3, and 4), and receiver operator characteristic analysis assessed model discrimination.

RESULTS

Prevalence of any ECC was 45%; median age was 62 years. Compared with those without ECC, those with ECC in 4 sites had increased hazards of 4.5, 7.1 and 2.3 for CHD events, CHD mortality, and all-cause mortality, respectively, independent of traditional risk factors (TRF; all P ≤ .05), and had ≥2-fold increased hazards for outcomes independent of coronary artery calcification (CAC). Each additional site of ECC was positively associated with each outcome in a graded fashion. When added to TRF, ECC significantly increased the area under the receiver operator characteristic curve for all outcomes and modestly increased the area under the curve for mortality beyond TRF + CAC (0.799 to 0.802; P = .03).

CONCLUSION

Increasing multisite ECC has a graded association with higher CHD and mortality risk, contributing information beyond TRF. Multisite ECC incidentally identified on imaging can be used to improve individualized risk prediction.

Coronary artery calcium and incident cerebrovascular events in an asymptomatic cohort. The MESA Study

OBJECTIVES

This study assessed the predictive value of coronary artery calcium (CAC) score for cerebrovascular events (CVE) in an asymptomatic multiethnic cohort.

BACKGROUND

The CAC score, a measure of atherosclerotic burden, has been shown to improve prediction of coronary heart disease events. However, the predictive value of CAC for CVE is unclear.

METHODS

CAC was measured at baseline examination of participants (N = 6,779) of MESA (Multi-Ethnic Study of Atherosclerosis) and then followed for an average of 9.5 ± 2.4 years for the diagnosis of incident CVE, defined as all strokes or transient ischemic attacks.

RESULTS

During the follow-up, 234 (3.5%) adjudicated CVE occurred. In Kaplan-Meier analysis, the presence of CAC was associated with a lower CVE event-free survival versus the absence of CAC (log-rank chi-square: 59.8, p < 0.0001). Log-transformed CAC was associated with increased risk for CVE after adjusting for age, sex, race/ethnicity, body mass index, systolic and diastolic blood pressure, total cholesterol, high-density lipoprotein cholesterol, cigarette smoking status, blood pressure medication use, statin use, and interim atrial fibrillation (hazard ratio [HR]: 1.13 [95% confidence interval (CI): 1.07 to 1.20], p < 0.0001). The American College of Cardiology/American Heart Association-recommended CAC cutoff was also an independent predictor of CVE and strokes (HR: 1.70 [95% CI: 1.24 to 2.35], p = 0.001, and HR: 1.59 [95% CI: 1.11 to 2.27], p = 0.01, respectively). CAC was an independent predictor of CVE when analysis was stratified by sex or race/ethnicity and improved discrimination for CVE when added to the full model (c-statistic: 0.744 vs. 0.755). CAC also improved the discriminative ability of the Framingham stroke risk score for CVE.

CONCLUSIONS

CAC is an independent predictor of CVE and improves the discrimination afforded by current stroke risk factors or the Framingham stroke risk score for incident CVE in an initially asymptomatic multiethnic adult cohort.

Abdominal aortic atherosclerosis at MR imaging is associated with cardiovascular events: the Dallas heart study

PURPOSE

To determine the value of two abdominal aortic atherosclerosis measurements at magnetic resonance (MR) imaging for predicting future cardiovascular events.

MATERIALS AND METHODS

This study was approved by the institutional review board and complied with HIPAA regulations. The study consisted of 2122 participants from the multiethnic, population-based Dallas Heart Study who underwent abdominal aortic MR imaging at 1.5 T. Aortic atherosclerosis was measured by quantifying mean aortic wall thickness (MAWT) and aortic plaque burden. Participants were monitored for cardiovascular death, nonfatal cardiac events, and nonfatal extracardiac vascular events over a mean period of 7.8 years ± 1.5 (standard deviation [SD]). Cox proportional hazards regression was used to assess independent associations of aortic atherosclerosis and cardiovascular events.

RESULTS

Increasing MAWT was positively associated with male sex (odds ratio, 3.66; P < .0001), current smoking (odds ratio, 2.53; P < .0001), 10-year increase in age (odds ratio, 2.24; P < .0001), and hypertension (odds ratio, 1.66; P = .0001). A total of 143 participants (6.7%) experienced a cardiovascular event. MAWT conferred an increased risk for composite events (hazard ratio, 1.28 per 1 SD; P = .001). Aortic plaque was not associated with increased risk for composite events. Increasing MAWT and aortic plaque burden both conferred an increased risk for nonfatal extracardiac events (hazard ratio of 1.52 per 1 SD [P < .001] and hazard ratio of 1.46 per 1 SD [P = .03], respectively).

CONCLUSION

MR imaging measures of aortic atherosclerosis are predictive of future adverse cardiovascular events.