A zero coronary artery calcium score in patients with stable chest pain is associated with a good prognosis, despite risk of non-calcified plaques.
Level 3 - non-randomized controlled study
Prospective observational cohort study
PubMed 31168373 · doi:10.1136/openhrt-2018-000945
What was done
A prospective cohort study was conducted at a single tertiary centre over 7 years in 1,753 consecutive patients presenting with stable chest pain undergoing coronary artery calcium (CAC) scoring with or without CT coronary angiography (CTCA) as part of routine care. The authors determined the prevalence of non-calcified plaque and obstructive stenosis among patients with a zero CAC score, and tracked major adverse cardiac events (MACE: cardiac death, non-fatal myocardial infarction, non-elective revascularisation) and all-cause mortality over a median follow-up of 2.2 years (range 1.0 to 7.0 years).
What was found
Of 1,753 patients, 915 (52.2%) had a CAC score of zero (mean age 56.8 ± 12.0 years; 46.2% male). Among 751 patients with zero CAC who underwent CTCA, 674 (89.7%) had normal coronary arteries, 63 (8.4%) had non-calcified CAD with < 50% stenosis, and 14 (1.9%) had ≥ 50% stenosis, yielding a negative predictive value of 98.1% for excluding ≥ 50% stenosis. Annualised MACE rates were 1.9 per 1,000 person-years in the zero CAC cohort versus 7.4 per 1,000 person-years in the non-zero CAC cohort (unadjusted HR 3.8, p = 0.009). Following multivariable adjustment for age, sex, and cardiovascular risk factors, the difference in MACE was not statistically significant (p = 0.19), and the adjusted HR for all-cause mortality was 2.1 (p = 0.27).
Why it matters
A zero CAC score in patients with suspected stable angina identifies a low-risk cohort with a low rate of obstructive CAD and low medium-term adverse cardiac event rates, although 10.3% still harbor non-calcified plaque.
Limits
The study was conducted at a single tertiary center. CTCA was not performed in all zero-CAC patients (82.1% received CTCA), introducing potential selection bias. Median follow-up was relatively short (2.2 years), and the low absolute event count in the zero-CAC cohort limited statistical power for multivariable regression models.
Cited by
- supports An individual can have a coronary artery calcium score of zero and still experience a heart attack due to non-calcified soft plaque.