Coronary Artery Calcium and Risk Factors for Predicting Mortality
What is the association and burden of coronary artery calcium (CAC) with long-term cause-specific mortality across the spectrum of baseline risk from low to high?
The CAC Consortium cohort is a multicenter cohort of 66,636 individuals without coronary heart disease (CHD) who underwent CAC testing with CAC divided into the standard four groups. The following risk factors (RFs) were considered: 1) current cigarette smoking, 2) dyslipidemia, 3) diabetes mellitus, 4) hypertension, and 5) family history of CHD. Death and cause of death were obtained from the Social Security Death Index Master File.
Mean age of the population was 54 (± 11) years and 67% were men. Approximately 17% had no RFs, 36% one RF, 32% two RFs, and 15% had ≥3 RFs. About 45% had a CAC = 0, 31% 1-100, 13% 100-400, and 11% ≥400. During the 12.5-year median follow-up, 3,158 (4.7%) deaths occurred, and 32% were cardiovascular disease (CVD) deaths. There was a high significant 16-fold and 23-fold increase in annualized CVD and CHD mortality rate among persons with a CAC score of ≥400 as compared with individuals with CAC = 0. Participants with ≥3 RFs had a smaller increased risk for CHD and CVD mortality (2.0- and 1.84-fold, respectively) compared to those without RFs. Across RF strata, CAC added prognostic information. For example, participants without RFs but with CAC ≥400 had significantly higher all-cause, non-CVD, CVD, and CHD mortality rates compared to individuals with ≥3 RFs and CAC = 0.
Across the spectrum of RF burden, higher CAC score is strongly associated with long-term all-cause mortality and a greater proportion of deaths due to CVD and CHD. Absence of CAC identifies people with a low risk over 12 years of follow-up with most deaths non-CVD in nature, regardless of RF burden.
This study supports the many population studies demonstrating that very high CAC scores are associated with increased CV and overall mortality including cancer, and that a CAC = 0 has a low overall mortality. But the endpoint of mortality should not be used to infer a very low or CAC = 0 can be used to avoid or delay lifestyle and statin therapy in low and borderline risk persons who have been shown to benefit from statins including smokers, diabetics, and those with risk enhancers such as ≥1 RFs with elevated lipoprotein(a), and low-density lipoprotein cholesterol >190 mg/dl or familial hypercholesterolemia. In contrast, those with a low estimated risk with an isolated low high-density lipoprotein cholesterol or family history of premature coronary artery disease and a CAC = 0 can avoid statins with careful follow-up and consideration for repeating the CAC score in 4-5 years.
Keywords: Coronary Disease, Diabetes Mellitus, Diagnostic Imaging, Dyslipidemias, Hydroxymethylglutaryl-CoA Reductase Inhibitors, Hypertension, Life Style, Plaque, Atherosclerotic, Primary Prevention, Risk Factors
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