What is the clinical evidence from this study?

Study design: Cohort. Population: Patients undergoing routine diagnostic chest CT without known cardiovascular disease (n=10410). Intervention: Severe coronary artery calcification (CAC score ≥6) vs. No coronary artery calcification (CAC score 0). Primary outcome: Incident fatal and non-fatal cardiovascular disease (CVD) events (HR 3.7, 95% CI 2.7-5.2).

May 20, 2011Open Access

Unrequested information from routine diagnostic chest CT predicts future cardiovascular events

Key Result

Severe coronary calcification incidentally detected on routine diagnostic chest CT increased the adjusted risk of future cardiovascular events by 3.7 times compared to patients with no calcification.

Study Design

Type

Cohort (n=10,410)

Blinding

Assessor-blinded

Multicenter

Yes

Structured PICO

Does subclinical coronary and aortic calcification detected on routine diagnostic chest CT predict future cardiovascular events in patients without known cardiovascular disease?

Population

10,410 subjects (>40 years) from a multicentre, clinical care-based cohort who underwent routine diagnostic chest CT. Excluded: history of symptomatic cardiovascular disease, poor prognosis (primary lung cancer, distant metastatic disease). Subcohort (n=1208) mean age 61.5 years, 58% male.

Intervention

Presence of subclinical coronary artery calcification (CAC) and thoracic aortic calcification (TAC) detected incidentally on routine diagnostic chest CT.

Comparator

Subjects with no coronary or aortic calcification (CAC score 0 or TAC score 0).

Outcome

Incident fatal and non-fatal cardiovascular disease (CVD) events (coronary heart disease, heart failure, peripheral arterial disease, aortic aneurysm, cerebrovascular disease, or non-rheumatic valvular disease).hard clinical

Incidental findings of coronary and aortic calcification on routine diagnostic chest CTs strongly predict future cardiovascular events, offering a free and opportunistic method for cardiovascular risk stratification.

Main Result

Effect estimate: HR 3.7 (95% CI 2.7-5.2)

Absolute Event Rate: 5.9% vs 0.7%

Limitations

No information from patients' medical records was available.
Exclusion of patients with symptomatic CVD was based only on CT reports, potentially missing some symptomatic patients.
Inability to adjust risk estimates for traditional CVD risk factors like hypertension, hyperlipidaemia, diabetes, and smoking.

Abstract

OBJECTIVES: An increase in the number of CT investigations will likely result in a an increase in unrequested information. Clinical relevance of these findings is unknown. This is the first follow-up study to investigate the prognostic relevance of subclinical coronary (CAC) and aortic calcification (TAC) as contained in routine diagnostic chest CT in a clinical care population. METHODS: The follow-up of 10,410 subjects (>40 years) from a multicentre, clinical care-based cohort of patients included 240 fatal to 275 non-fatal cardiovascular disease (CVD) events (mean follow-up 17.8 months). Patients with a history of CVD were excluded. Coronary (0-12) and aortic calcification (0-8) were semi-quantitatively scored. We used Cox proportional-hazard models to compute hazard ratios to predict CVD events. RESULTS: CAC and TAC were significantly and independently predictive of CVD events. Compared with subjects with no calcium, the adjusted risk of a CVD event was 3.7 times higher (95% CI, 2.7-5.2) among patients with severe coronary calcification (CAC score ≥6) and 2.7 times higher (95% CI, 2.0-3.7) among patients with severe aortic calcification (TAC score ≥5). CONCLUSIONS: Subclinical vascular calcification on CT is a strong predictor of incident CVD events in a routine clinical care population.

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