Coronary calcium on lung scans may flag heart risk in pulmonary embolism patients

Coronary artery calcification is often clearly visible on the CT scans performed to diagnose acute pulmonary embolism, yet radiologists frequently fail to mention it in their reports. A narrative review now argues that this overlooked finding could carry a double significance: it may help refine prognosis after a confirmed embolic event, and it offers a free, radiation-free window onto previously unrecognised coronary atherosclerosis. The review, published in the Egyptian Journal of Radiology and Nuclear Medicine, pulls together the scattered evidence on calcium detected during routine CT pulmonary angiography and concludes that the two potential roles must be kept strictly separate.

Acute pulmonary embolism is the third most common acute cardiovascular syndrome, with an estimated age-adjusted incidence of 60 to 120 per 100,000 person-years and a 30-day mortality of 2 to 10 percent despite advances in anticoagulation and risk stratification. Accurate prognostication at the moment of diagnosis determines whether patients are treated as outpatients, monitored intensively, or considered for reperfusion therapy. Current practice integrates clinical scores such as the Pulmonary Embolism Severity Index, cardiac biomarkers including troponin and B-type natriuretic peptide, and imaging markers of right ventricular strain measured on the same CT scan.

The problem, the review argues, is that acute right ventricular findings mainly reflect the haemodynamic consequences of the embolic event. They may not capture the chronic cardiovascular reserve of the patient. Two people with similar right ventricular dilation can differ enormously in underlying coronary artery disease, heart failure, or chronic lung disease. Coronary artery calcification, a marker of coronary atherosclerotic plaque burden, is a natural candidate for capturing that hidden vulnerability, and it sits within the field of view of every pulmonary embolism CT without requiring any additional scan or radiation exposure.

The evidence is far from straightforward. In one cohort of 479 inpatients with confirmed acute pulmonary embolism who also underwent echocardiography, any visible coronary calcification was associated with 30-day pulmonary embolism-related mortality in unadjusted analysis, with an odds ratio of 3.5. After adjustment for age and sex the association weakened, and in the fully adjusted model including right ventricular strain, peak troponin T, and cardiovascular risk factors it was no longer statistically significant, with an odds ratio of 3.4 and a confidence interval crossing one. A similar pattern held for all-cause mortality: the unadjusted odds ratio of 3.1 fell to a non-significant 2.6 after full adjustment.

Other studies used different methods entirely. One group of 118 patients graded each of the four main coronary arteries from 0 to 3 and summed the results to a total score of 0 to 12, finding that a data-derived threshold above 5.5 was independently associated with 30-day pulmonary embolism-related mortality. A retrospective re-review of 245 confirmed cases used the Weston score and found that a score of 6 or higher remained associated with six-month all-cause mortality in the overall multivariable analysis. However, 20 percent of that cohort had active cancer, and once patients with malignancy were excluded the calcium score lost its independent association, leaving only the Glasgow Prognostic Score significant. A fourth study of 400 consecutive patients found that any calcification was associated with three-year all-cause mortality in univariable analysis, and that the total score remained independently associated with all-cause mortality after adjustment for age, but not with pulmonary embolism-related mortality.

The review stresses that these studies cannot simply be pooled. They differ in how calcium was defined, in the populations studied, and in how thoroughly confounders were adjusted. Some reported unadjusted estimates, and data-derived thresholds may overfit small samples. No large prospective study has yet demonstrated that adding coronary calcification to a validated acute pulmonary embolism risk model improves discrimination, calibration, reclassification, or clinical decision-making beyond established tools such as the severity index, the right ventricular to left ventricular diameter ratio, troponin, and B-type natriuretic peptide.

There is also a technical catch. Dedicated quantitative calcium scoring is conventionally performed on non-contrast, ECG-gated cardiac CT using the Agatston method. Routine pulmonary embolism CT is contrast-enhanced and non-gated, and intravascular iodine and cardiac motion can obscure or mimic small high-attenuation foci. The conventional 130-HU Agatston threshold cannot simply be applied. In a paired validation study, visual assessment on contrast-enhanced chest CT had 83 percent sensitivity and 100 percent specificity for the presence of calcification compared with dedicated scoring CT, but every false-negative case had a low calcium burden below an Agatston score of 30. A visual report of no calcification seen therefore should not be treated as equivalent to a definitive Agatston score of zero.

Higher attenuation thresholds have been explored on contrast-enhanced coronary CT angiography, including thresholds above 351 and 600 HU, but performance depended on the reconstruction method and clinically relevant reclassification of calcium categories persisted. Even the better-performing approach was not equivalent to standard non-contrast scoring, and such thresholds preferentially reduce sensitivity for small or lower-density calcifications. The review concludes that the most practical current approach is a whole-patient visual ordinal grade of none, mild, moderate, or severe, consistent with existing guidance for non-gated thoracic CT, identifying calcification from morphology and location along the expected coronary course rather than from a fixed HU threshold.

The opportunistic message may prove more robust than the prognostic one. In a cohort of 414 patients undergoing CT pulmonary angiography for suspected pulmonary embolism, of whom only 18.1 percent actually had the condition, moderate-to-severe visual calcification independently predicted a composite of cardiovascular death, myocardial infarction, or coronary revascularisation, with a hazard ratio of 5.30, and all-cause mortality, with a hazard ratio of 1.52, after adjustment for age, sex, cardiovascular risk factors, and pulmonary embolism diagnosis. A separate analysis of 100 patients scanned for non-cardiac chest pain reported major adverse cardiac events in 46.8 percent of those with calcification versus 3.8 percent without, although that was an unadjusted conference-abstract analysis retained only as contextual evidence.

The review also flags underreporting as a systemic problem. One study found that coronary calcification was omitted from the original CT report in 45 percent of patients in whom it was subsequently identified. Because the scan is already acquired for a clinically necessary indication, confidently visible calcification identifies coronary atherosclerosis without additional imaging or radiation, and the report should support assessment of modifiable cardiovascular risk factors rather than automatically triggering ischaemia testing in asymptomatic patients. Future research, the authors argue, should separate confirmed from suspected pulmonary embolism populations, prespecify the calcium exposure definition, report acquisition and reconstruction parameters and reader reproducibility, and test incremental value against established risk models before coronary calcification can be recommended for acute pulmonary embolism triage.

Subject of Research: Coronary artery calcification detected on CT pulmonary angiography as a prognostic marker in acute pulmonary embolism

Article Title: CTPA-detected coronary artery calcification as a prognostic marker in acute pulmonary embolism: a narrative review

Article References: Naidu, J., Baskaradoss, V., Basit, A., & Shawki, M. (2026). CTPA-detected coronary artery calcification as a prognostic marker in acute pulmonary embolism: a narrative review. Egyptian Journal of Radiology and Nuclear Medicine, 57(1), Article 213. https://doi.org/10.1186/s43055-026-01881-2

Image Credits: AI Generated

DOI: 10.1186/s43055-026-01881-2

Keywords: pulmonary embolism, coronary artery calcification, CT pulmonary angiography, risk stratification, opportunistic screening, coronary atherosclerosis, Agatston score, right ventricular strain, prognostic markers, cardiovascular risk assessment, narrative review, radiology