S0983 Coronary Artery Calcium Score and All-Cause Mortality in Liver Transplant Recipients: A Retrospective Analysis

Abstract

INTRODUCTION: Cardiovascular disease is a major cause of death after liver transplantation. Pre-transplant cardiac risk stratification generally involves pharmacologic stress testing, as well as coronary artery angiography in high-risk patients. Coronary artery calcium (CAC) score is a non-invasive estimation of total calcified plaque in coronary arteries. CAC score has been shown to be associated with 1-month post-transplant mortality; however, it has not been studied as a predictor of long-term outcomes in liver transplant recipients. METHODS: We retrospectively studied patients who underwent liver transplantation at Johns Hopkins Hospital between 1/1/2015 and 12/31/2018 who had a pre-transplant CAC score measured. Patients were divided into 3 groups: CAC score 0 (group 1), CAC score 1–400 (group 2) and CAC score >400 (group 3). All-cause mortality in the 3 groups was compared using Kaplan-Meier curves and the log-rank test, with statistical significance defined as P < 0.05. RESULTS: A total of 412 adult patients underwent liver transplantation, of which 155 patients had a CAC score measured as part of pre-transplant cardiovascular evaluation. CAC group 1, 2, and 3 and 37, 82, and 36 patients, respectively. The median age was 60, median body mass index (BMI) was 28.6, and median model for end-stage liver disease (MELD) score was 19, with no significant difference between groups (Table 1). The cohort was 38.1% female, with significantly lower proportion of females in higher CAC score groups (P = 004). At 1 year, death occurred in 3 (8.1%), 7 (8.5%) and 2 (5.6%) patients in groups 1, 2, and 3, respectively (Table 2). At 2 years, there were 5 (15.2%), 12 (16.9%), and 6 (20.7%) deaths in the three groups, respectively. At 3 years, there were 6 (23.1%), 13 (24.5%), and 8 (32.0%) deaths in the 3 groups, respectively. There was no significant difference in all-cause mortality between CAC score groups (Figure 1). CONCLUSION: CAC score may be useful in cardiac risk stratification prior to liver transplantation. In this study, there was no significant difference in 1-, 2-, or 3-year all-cause mortality between CAC score groups. However, there was a non-significant trend towards increased all-cause mortality with higher calcium scores at 2 and 3 years of follow up. Further research is needed with a larger sample size and examination of cardiac risk factors to better evaluate the prognostic utility of CAC score in this population.Table 1.: Baseline characteristics by coronary artery calcium score groups. Continuous variables in this table were assumed to be skewed in the population, thus nonparametric k-test for equality of medians was used to compare medians between groups. Fisher’s exact test was used to compare categorical variables. a. body mass index (BMI) b. model for end-stage liver disease (MELD) c. coronary artery calcium (CAC)Table 2.: All-cause mortality at 1, 2, and 3 years after liver transplant, stratified by coronary artery calcium score groups. a. coronary artery calcium (CAC)Figure 1.: Three-year Kaplan-Meier survival curves stratified by coronary artery calcium score groups. No significant difference between groups (P = 0.71). Abbreviations: coronary artery calcium (CAC).