Quantitative pericardial calcification score as an imaging marker for atrial fibrillation in constrictive pericarditis

Constrictive pericarditis (CP) is frequently complicated by atrial fibrillation (AF), which worsens prognosis. Prior studies only qualitatively described pericardial calcification in relation to AF, lacking quantitative thresholds. This study aimed to quantify pericardial calcification via CT and investigate its association with AF in CP. We retrospectively analyzed 221 tuberculous CP patients, classified into an AF group ( n = 42) and a non-AF group ( n = 179). Pericardial calcification was quantified using the Agatston score. An internally derived exploratory cutoff for discriminating AF was determined via ROC analysis. A multivariable model incorporating the log-transformed calcification score and age was constructed, with internal validation performed using 500 bootstrap resamples. Firth’s penalized regression was used as a sensitivity analysis. Compared with the non-AF group, patients in the AF group were older, exhibited longer disease duration and significantly higher calcification scores (14,777.05 [30,281.80] vs.0.00 [0.00], P < 0.001). The internally derived exploratory cutoff for the log-transformed calcification score was 5.867 (raw score: 352.2), yielding a univariate AUC of 0.872. Multivariable analysis confirmed that both the log-transformed calcification score (OR 1.537, bootstrap 95% CI: 1.400–1.847) and age (OR 1.040, bootstrap 95% CI: 1.014–1.079) were independently associated with AF. The composite model achieved an AUC of 0.903. Internal bootstrap validation yielded an optimism-corrected AUC of 0.898 and a calibration slope of 0.969, indicating robust performance and favorable calibration. Sensitivity analysis using Firth’s regression yielded consistent estimates (calcification OR 1.516; age OR 1.038), confirming robustness. Pericardial calcification and age are independent factors associated with AF in CP. A log-transformed calcification score of 5.867 (equivalent to a raw score of 352.2) was identified as an internally derived exploratory cutoff for AF.