Predictive value of tibial and coronary artery calcification scores for cardiac and lower extremity events.

Abstract

Objective: The extent of calcification in tibial and coronary arteries predicts major ischemic events. Tibial calcification predicts ischemic events in a manner independent of the degree of associated atherosclerotic occlusive disease while coronary calcification can improve risk stratification in patients at intermediate risk for cardiovascular disease. We thus assessed the relationship between tibial and coronary calcification, the influence of cardiovascular risk factors on their extent, and their individual predictive value on major adverse limb and cardiac events (MALE and MACE).

Methods: We retrospectively reviewed images and collected demographic and cardiovascular risk factor data of patients who underwent CT scans of the lower extremities and chest. Calcification in the tibial and coronary arteries were identified and scored using a semi-automated method. A spearman correlation coefficient was calculated using tibial and coronary artery calcification scores (TAC and CAC). Ordinal logistic regression and multiple linear regression were performed using cardiovascular and demographic factors as covariates. Log-rank test and Kaplan-Meier estimate were completed to assess MACE and MALE free probability.

Results: A total of 101 patients were identified who met inclusion criteria. There was a strong correlation (r=0.76) between CAC and TAC scores. Severe CAC (defined as > 400) and severe TAC (defined as > 500) scores were both associated with advanced age, male sex, a history of smoking, and diabetes. Renal disease was associated with a high TAC score but not CAC. An increasing TAC score was associated with increased MACE (p<0.0001) and MALE (p=0.039). However, increasing CAC was only associated with increased MACE (p=0.0036).

Conclusion: We provide data suggesting that TAC and CAC share similar risk factors and are highly correlated. Interestingly, TAC predicts both MACE and MALE, while CAC is best at predicting coronary, but not lower extremity events. Further studies are needed to understand the contributions of arterial calcification to myocardial and lower extremity ischemia.