Use of Computed Tomography Coronary Calcium Score for Coronary Artery Disease Risk Stratification During Liver Transplant Evaluation

Background

End-stage liver disease (ESLD) is not considered a risk factor for atherosclerotic cardiovascular disease (ASCVD). However, lifestyle characteristics commonly associated with increased ASCVD risk are highly prevalent in ESLD. Emerging literature shows a high burden of asymptomatic coronary artery disease (CAD) in patients with ESLD and a high ASCVD risk in liver transplantation (LT) recipients. Coronary artery calcium score (CAC) is a noninvasive test providing reliable CAD risk stratification. We implemented an LT evaluation protocol with CAC playing a central role in triaging and determining the need for further CAD assessment. Here, we inform our results from this early experience.

Methods

Patients with ESLD referred for LT evaluation were prospectively studied. We compared accuracy of CAC against that of CAD risk factors/scores, troponin I, dobutamine stress echocardiogram (DSE), and single-photon emission computed tomography (SPECT) to detect coronary stenosis ≥70 (CAD ≥ 70) per left heart catheterization (LHC). Thirty-day post-LT cardiac outcomes were also analyzed.

Results

One hundred twenty-four of 148 (84%) patients underwent CAC, 106 (72%) DSE/SPECT, and 50 (34%) LHC. CAC ≥ 400 was found in 35 (28%), 100 to 399 in 17 (14%), and <100 in 72 (58%). LHC identified CAD ≥ 70% in 8 of 29 (28%), 2 of 9 (22%), and 0 of 4, respectively. Two acute coronary syndromes occurred after LT in a patient with CAC 811 (CAD < 70%), and one with CAC 347 (CAD ≥ 70%). No patients with CAC < 100 presented with acute coronary syndrome after LT. When using CAD ≥ 70% as primary endpoint of LT evaluation, CAC ≥ 346 was the only test showing predictive usefulness (negative predictive value 100%).

Conclusions

CAC is a promising tool to guide CAD risk stratification and need for LHC during LT evaluation. Patients with a CAC < 100 can safely undergo LT without the need for LHC or cardiac stress testing, whereas a CAC < 346 accurately rules out significant CAD stenosis (≥70%) on LHC, outperforming other CAD risk-stratification strategies.

The tertiary hospital laboratory; a novel avenue of opportunistic screening of familial hypercholesterolemia

Background

Familial hypercholesterolemia (FH) is a common monogenic hereditary lipid disorder characterised by increased serum low-density lipoprotein cholesterol (LDL-cholesterol) concentrations and high risk of premature atherosclerotic cardiovascular disease. The prevalence of FH identified in a tertiary hospital laboratory was investigated by performing an opportunistic screen for index cases.

Methods

The prevalence of likely FH based on LDL-cholesterol thresholds >4.9 mmol/L as employed by the Dutch Lipid Clinic Network Criteria (DLCNC) score was evaluated retrospectively in a single tertiary hospital laboratory over a six-month period (July to December 2016).

Results

4943 lipid profiles screened, 106 patients (mean age 53.2 ± 12.9 and 41% male) had LDL-cholesterol of >4.9 mmol/L after exclusion of 5 patients (0.1%) with secondary causes. Possible (n = 90) and probable/definite (n = 16) FH according to DLCNC score was seen in 1.8% and 0.4% of the overall screened population, respectively.

Conclusions

Point prevalence of screening for FH in patients undergoing lipid profile testing in a tertiary hospital laboratory was comparable with prevalence of FH in general population (based on 1 in 200-250). This supports the benefit of establishing an efficient "alert system" in conjunction with a trigger "reflex testing" to facilitate further formal FH scoring and exclusion of possible secondary causes of hyperlipidemia in potential index FH.