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Coronary artery calcification testing reliably predicts long-term mortality
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Coronary artery calcification testing accurately predicted all-cause mortality in asymptomatic patients over a 15-year period, according to recent data published in Annals of Internal Medicine.
“This test predicts the risk of [MI] better than any other diagnostic heart test that we have, especially in asymptomatic patients,” James K. Min, MD, director of the Dalio Institute of Cardiovascular Imaging at New York-Presbyterian Hospital and Weill Cornell Medical College, said in a press release. “It embodies the goal of precision medicine: namely, to precisely identify and exclude the patients who have or do not have disease that places them at heightened risk of [MI].”
Min, who also is a professor of radiology and of medicine at Weill Cornell Medical College, and colleagues conducted an observational cohort study of 9,715 asymptomatic patients (86% white) who underwent coronary artery calcification (CAC) testing with electron beam tomography or multislice CT at one outpatient clinic in the Nashville, Tennessee, area between 1996 and 1999 as part of a screening outreach program. The primary endpoint was time to all-cause mortality. The mean long-term follow-up for surviving patients was 14.6 years.
There were 936 deaths reported as of May 1, 2014. Unadjusted all-cause mortality rates correlated with increasing CAC scores: 3% for those who scored 0, 6% for those who scored from 1 to 10 (HR = 1.68), 9% for those who scored from 11 to 99 (HR = 2.91), 14% for those who scored from 100 to 399 (HR = 4.52), 21% for those who scored from 400 to 1,000 (HR = 5.53) and 28% for those who scored 1,000 or more (HR= 6.26; P < .001 for all).
The researchers assessed the predictive power of CAC testing by comparing the use of CV risk factors and CAC score in combination with CV risk factors alone. According to the results, CAC scores combined with CV risk factors correctly reclassified 27.9% cases of all-cause mortality and yielded a categorical net reclassification improvement of 0.21 for cutoff points ranging from less than 7.5% to at least 22.5% (95% CI, 0.16-0.32). However, 7.4% of cases were misclassified to a higher risk category compared with the use of CV factors alone. Alternative cut points (< 10% to ≥ 20%) increased the net reclassification improvement to 0.24 and the amount of appropriately reclassified mortalities to 34.7%, while increasing the proportion of misclassified survivors to 10.8%.
“The use of all-cause mortality as an endpoint, particularly for longer follow-up, expands the evidence base for a novel biomarker, such as CAC, beyond the traditional CVD outcomes,” the researchers wrote. “Although calcification is a disease-specific marker of the burden of subclinical atherosclerosis, our prognostic models estimating all-cause mortality may be indicative of its predictive value as a global measure of vascular health.” – by Stephanie Viguers
Disclosure: Min reports receiving grants from Arineta, AstraZeneca, Bristol-Myers Squibb, General Electric Healthcare, HeartFlow, Michael Wolk Heart Foundation, NHLBI, National Research Foundation of Korea, Philips Healthcare and Vital Images.
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