Coronary artery disease and liver transplantation: the state of the art

Assessment of Vascular and Valvular Calcification Improves Screening for Coronary Artery Disease Before Liver Transplantation

Coronary artery disease (CAD) is common in patients with cirrhosis who underwent orthotopic liver transplantation (OLT) evaluation and stress echocardiogram (echo) has a low sensitivity in these patients. This study aimed to assess the impact of vascular and valvular calcification on the ability to identify CAD before OLT. We performed a case-control study of 88 patients with and 97 without obstructive CAD who underwent OLT evaluation. All patients had a preoperative stress echo, abdominal computed tomography, and cardiac catheterization. A series of nested logistic regression models of CAD were fit by adding independent variables of vascular (including coronary) calcification, aortic and mitral valve calcification, age, gender, and history of diabetes mellitus requiring insulin to a baseline model of abnormal stress echo. Compared with stress echo alone, identification of the presence or absence of vascular and valvular calcification on routine preoperative computed tomography and echo improved the diagnostic performance for the detection of CAD based on coronary angiogram when combined with stress echo in patients with cirrhosis who underwent OLT evaluation (area under the curve 0.58 vs 0.73, p <0.001), which is even further improved when age, gender, and history of diabetes mellitus requiring insulin are considered (area under the curve 0.58 vs 0.80, p <0.001). Achieving target heart rate (p = 0.92) or rate-pressure product >25,000 (p = 0.63) did not improve the ability of stress echo to identify CAD. In conclusion, the use of abdominal vascular, coronary artery, and valvular calcification, along with stress echo, improves the ability to identify and rule out obstructive CAD before OLT compared with stress echo alone.

Cardiac Risk Stratification in Liver Transplantation: Results of a Tiered Assessment Protocol Based on Traditional Cardiovascular Risk Factors

Coronary artery disease (CAD) confers increased perioperative risk in patients undergoing liver transplantation (LT). Although routine screening for CAD is recommended, there are limited data on the effectiveness of screening strategies. We evaluated the safety and efficacy of a 3-tiered cardiac risk-assessment protocol that stratifies patients based on age and traditional cardiac risk factors. We peformed a single-center, prospective, observational study of consecutive adult patients undergoing LT assessment (2010-2017). Patients were stratified into low-risk (LR), intermediate-risk (IR), or high-risk (HR) cardiac groups and received standardized investigations with selective use of transthoracic echocardiography (TTE), dobutamine stress echocardiography (DSE), computed tomography coronary angiography (CTCA), and coronary angiography (CA). Primary outcomes were cardiac events (CEs) and cardiovascular death up to 30 days after LT. Overall, 569 patients were included, with 76 patients identified as LR, 256 as IR, and 237 as HR. Cardiac risk factors included diabetes mellitus (26.0%), smoking history (47.3%), hypertension (17.8%), hypercholesterolemia (7.2%), family (17.0%) or prior history of heart disease (6.0%), and obesity (27.6%). Of the patients, 42.0% had ≥2 risk factors. Overall compliance with the protocol was 90.3%. Abnormal findings on TTE, DSE, and CTCA were documented in 3, 23, and 44 patients, respectively, and 12 patients were not listed for transplantation following cardiac assessment (1 LR, 2 IR, and 9 HR). Moderate or severe CAD was identified in 25.4% of HR patients on CTCA following a normal DSE. CEs were recorded in 7 patients (1.2%), with 2 cardiovascular deaths (0.4%). Cardiac risk stratification based on traditional cardiac risk factors with the selective use of DSE, CTCA, and CA is a safe and feasible approach that results in a low perioperative cardiac event rate.

Diagnostic accuracy of cardiac testing for coronary artery disease in potential liver transplant recipients: A systematic review and meta-analysis

Background

The incidence of coronary artery disease (CAD) in Liver transplant (LT) patients is much higher than prior estimates and the morbidity and mortality are significant in this group of patients. Coronary angiography is the gold standard for detection of CAD, a non-invasive test that allows appropriate risk stratification would be preferred. In this systematic review and meta-analysis, we sought to assess the pooled diagnostic accuracy of various noninvasive cardiac imaging tests in detecting CAD in patients listed for LT.

Methods

We performed a systematic review and meta-analysis of studies comparing sensitivity and specificity of non-invasive tests to that of coronary angiography in diagnosing coronary artery disease in patients undergoing liver transplantation.

Results

Five studies (616 participants) evaluated myocardial perfusion imaging (MPI); five studies (1243 participants) dobutamine stress echocardiography (DSE); and three (87 participants), other tests. MPI had a pooled sensitivity of 0.62 (95% CI 0.37, 0.83), specificity of 0.60 (95% CI 0.39, 0.79), diagnostic odds ratio (DOR) of 2.5 (95% CI 1.7, 5.64) and Area under the curve (AUC) 0.649. DSE had a pooled sensitivity of 0.25 (95%CI 0.09, 0.51), specificity of 0.68 (95% CI 0.44, 0.84) and DOR of 0.7 (95% CI 0.12, 3.84).

Conclusions

Our results show that both MPI and DSE are not effective screening tools for detecting CAD in patients with end-stage liver disease (ESLD). Future studies are needed to evaluate the role of real-time myocardial contrast echocardiography (RTMCE) and coronary artery calcium score (CAC) with coronary CT angiography in patients with ESLD.

Preoperative Evaluation of Coronary Artery Disease in Liver Transplant Candidates: Many Unanswered Questions in Clinical Practice

Cardiovascular (CV) complications represent the first non-graft-related cause of death and the third overall cause of death among patients undergoing liver transplantation (LT). History of coronary artery disease is related to increased CV mortality following LT. Although it is of paramount importance to stratify CV risk in pre-LT patients, there is no consensus regarding the choice of the optimal non-invasive cardiac imaging test. Algorithms proposed by scientific associations include non-traditional risk factors, which are associated with increased cardiac risk profiles. Thus, an individualized pre-LT evaluation protocol should be followed. As the average age of patients undergoing LT and the number of candidates continue to rise, the “3 W” questions still remain unanswered, Who, Which and When? Who should be screened for coronary artery disease (CAD), which screening modality should be used and when should the asymptomatic waitlisted patients repeat cardiac evaluation? Prospective studies with large sample sizes are warranted to define an algorithm that can provide better risk stratification and more reliable survival prediction.

Intraoperative Type I Acute Myocardial Infarction During Liver Transplant Requiring Intra-Aortic Balloon Pump: A Case Report

We describe a complex case of liver transplant in a 70-year-old male patient with no known history of coronary artery disease, normal preoperative left ventricular function, and negative preoperative cardiac workup who developed progressive intra-operative left ventricular myocardial dysfunction secondary to class I acute myocardial infarction, ultimately requiring intraoperative intra-aortic balloon pump insertion to optimize myocardial perfusion. Management of myocardial ischemia was complicated by bleeding in the setting of coagulopathy necessitating correction. Once hemostasis was achieved, the patient immediately underwent coronary angiography and bare metal stent placement in the mid-left anterior descending coronary artery for an acute plaque rupture.

NAFLD Epidemiology, Emerging Pharmacotherapy, Liver Transplantation Implications and the Trends in the United States

Nonalcoholic fatty liver disease (NAFLD) is a hepatic manifestation of metabolic syndrome. The spread of obesity worldwide in pandemic proportions has led to a rapid rise of NAFLD in developed and developing countries alike. There are no approved pharmacological agents to treat steatohepatitis or advanced fibrosis but obeticholic acid recently has shown some promise in phase III trial. Currently, NAFLD is the number one etiology for simultaneous liver and kidney transplantation in the USA, second most common indication for liver transplantation (LT) and projected to become number one very soon. LT for NAFLD poses unique challenges, as these patients are generally older, obese and more likely to have a number of metabolic risk factors. Bariatric surgery is an option and can be considered if a structured weight loss program does not achieve the sustained weight loss goal. Comprehensive cardiovascular risk assessment and aggressive management of comorbid conditions are crucial in the LT evaluation process to improve post-transplant survival. Recurrent nonalcoholic steatohepatitis after LT is not uncommon, and thus warrants primary and secondary prevention strategies through a multidisciplinary approach. Prevalence of NAFLD in a donor population is a unique and growing concern that limits the access to quality liver grafts.

Liver transplantation and cardiac illness: Current evidences and future directions

Contraindications to liver transplantation are gradually narrowing. Cardiac illness and chronic liver disease may manifest independently or may be superimposed on each other due to shared pathophysiology. Cardiac surgery involving the cardiopulmonary bypass in patients with Child-Pugh Class C liver disease is associated with a high risk of perioperative morbidity and mortality. Liver transplantation involves hemodynamic perturbations, volume shifts, coagulation abnormalities, electrolyte disturbances, and hypothermia, which may prove fatal in patients with cardiac illness depending upon the severity. Additionally, cardiovascular complications are the major cause of adverse postoperative outcomes after liver transplantation even in the absence of cardiac pathologies. Clinical decision-making has remained an unsettled issue in these clinical scenarios. The absence of randomized clinical studies has further crippled our endeavours for a consensus on the management of patients with end-stage liver disease with cardiac illness. This review seeks to address this complex clinical setting by gathering information from published literature. The management algorithm in this review may facilitate clinical decision making and augur future research.

Preoperative dobutamine stress echocardiography in patients undergoing orthotopic liver transplantation

BACKGROUND

Coronary artery disease (CAD) is associated with increased mortality in patients who undergo orthotopic liver transplantation (OLT). Chronic vasodilatory state and poor exercise tolerance in patients with end-stage liver disease make dobutamine stress echocardiography (DSE) preferred for preoperative evaluation of CAD prior to OLT. We studied the incidence of positive DSE results and the association between DSE results and perioperative and longer-term events.

HYPOTHESIS

DSE results pre-OLT will predict short and long term outcomes.

METHODS

We studied 460 patients who underwent DSE within 1 year prior to OLT between 2004 and 2011. Primary events included death and MI at 30 days post-OLT. We also recorded longer-term deaths.

RESULTS

Four patients (0.9%) had an ischemic response to DSE, 360 (78%) were normal, and 96 (21%) were nondiagnostic. Fourteen patients (3%) had a primary event at 30 days following OLT (13 deaths and 1 NSTEMI), and there were 108 (24%) deaths at 4.6±2 years of follow-up. No patient with ischemia on DSE had a 30-day event. The accuracy, sensitivity, specificity, and positive and negative predictive values of DSE that was not normal (ie, ischemic or nondiagnostic response) to predict 30-day post-OLT events were 76%, 14%, 78%, 2%, and 97%, respectively. On Cox survival analysis, only baseline left ventricular ejection fraction (HR: 0.90, 95% CI: 0.85-0.96, P < 0.001) was associated with longer-term deaths.

CONCLUSIONS

Patients undergoing pre-OLT DSE have very low incidence of an ischemic response on DSE, and it has no association with 30-day events.

Cardio-hepatic risk assessment by CMR imaging in liver transplant candidates

BACKGROUND

The preoperative workup of orthotopic liver transplantation (OLT) patients is practically complex given the need for multiple imaging modalities. We recently demonstrated in our proof-of-concept study the value of a one-stop-shop approach using cardiovascular MRI (CMR) to address this complex problem. However, this approach requires further validation in a larger cohort, as detection of hepatocellular carcinoma (HCC) as well as cardiovascular risk assessment is critically important in these patients. We hypothesized that coronary risk assessment and HCC detectability is acceptable using the one-stop-shop CMR approach.

METHODS

In this observational study, patients underwent CMRI evaluation including cardiac function, stress CMR, thoracoabdominal MRA, and abdominal MRI on a standard MRI scanner in one examination.

RESULTS

Over 8 years, 252 OLT candidates underwent evaluation in the cardiac MRI suit. The completion rates for each segment of the CMR examination were 99% for function, 95% completed stress CMR, 93% completed LGE for viability, 85% for liver MRI, and 87% for MRA. A negative CMR stress examination had 100% CAD event-free survival at 12 months. A total of 63 (29%) patients proceeded to OLT. Explant pathology confirmed detection/exclusion of HCC.

CONCLUSIONS

This study further defines the population suitable for the one-stop-shop CMR concept for preop evaluation of OLT candidates providing a road map for integrated testing in this complex patient population for evaluation of cardiac risk and detection of HCC lesions.

Myocardial perfusion imaging is an effective screening test for coronary artery disease in liver transplant candidates

A reliable screening test for coronary artery disease (CAD) in liver transplant (LT) candidates with end-stage liver disease is essential because a high percentage of perioperative mortality and morbidity is CAD-related. In this study, the effectiveness of myocardial perfusion imaging (MPI) for identification of significant CAD in LT candidates was evaluated. Records of 244 patients meeting criteria for MPI were evaluated: 74 met inclusion criteria; 40 had a positive MPI and cardiology follow-up; 27 had a negative MPI and underwent LT; and seven had a negative MPI and then had coronary angiography or a significant cardiac event. A selective MPI interpretation strategy was established where MPI-positive patients were divided into high, intermediate, and low CAD risk groups. The overall incidence of CAD in this study population was 5.1% and our strategy resulted in PPV 20%, NPV 94%, sensitivity 80%, and specificity 50% for categorizing CAD risk. When applied only to the subset of patients categorized as high CAD risk, the strategy was more effective, with PPV 67%, NPV 97%, sensitivity 80%, and specificity 94%. We determined that renal dysfunction was an independent predictive factor for CAD (p < 0.0001, odds ratio = 8.1), and grades of coronary occlusion correlated significantly with chronic renal dysfunction (p = 0.0079).

Role of cardiovascular intervention as a bridge to liver transplantation

End stage liver disease (ESLD) is associated with many specific derangements in cardiovascular physiology, which influence perioperative outcomes and may profoundly influence diagnostic and management strategies in the preoperative period. This review focuses on evidence-based diagnosis and management of coronary, hemodynamic and pulmonary vascular disease in this population with an emphasis on specific strategies that may provide a bridge to transplantation. Specifically, we address the underlying prevalence of cardiovascular disease states in the ESLD population, and relevant diagnostic criteria thereof. We highlight traditional and non-traditional predictors of cardiovascular outcomes following liver transplant, as well as data to guide risk-factor based diagnostic strategies. We go on to discuss the alterations in cardiovascular physiology which influence positive- and negative-predictive values of standard noninvasive testing modalities in the ESLD population, and review the data regarding the safety and efficacy of invasive testing in the face of ESLD and its co-morbidities. Finally, based upon the totality of available data, we outline an evidence-based approach for the management of ischemia, heart failure and pulmonary vascular disease in this population. It is our hope that such evidence-driven strategies can be employed to more safely bridge appropriate candidates to liver transplant, and to improve their cardiovascular health and outcomes in the peri-operative period.

Cardiac and pulmonary issues in LT assessment candidates

With the incidence of liver disease increasing worldwide, a growing number of patients are being referred for assessment for liver transplant (LT). Unfortunately, the donor pool is not expanding at the same rate, which consequentially results in increasing demand on a finite resource. It is therefore imperative that the candidate who undergoes an LT gets maximal benefit with a resultant maximal increase in life expectancy. This article addresses some of the main cardiac and pulmonary issues that may occur in LT assessment candidates.

Comparison of the frequency of coronary artery disease in alcohol-related versus non-alcohol-related endstage liver disease

There are conflicting data as to the prevalence of coronary artery disease (CAD) in patients with end-stage liver disease (ESLD) being assessed for liver transplantation (LT). The aims of this study were to compare the prevalence of CAD in patients with alcohol-related versus non-alcohol-related ESLD and to assess the diagnostic utility of dobutamine stress echocardiography (DSE) in predicting angiographically important CAD. Consecutive patients with ESLD being assessed for LT (n = 420, mean age 56 ± 8 years) were identified and divided into groups of those with alcohol-related ESLD (n = 125) and non-alcohol-related ESLD (n = 295). Demographic characteristics, CAD risk factors, results of DSE, and coronary angiographic characteristics were recorded. There were no significant differences in age or CAD risk factors between groups. The incidence of severe CAD (>70% diameter stenosis) was 2% in the alcohol-related ESLD group and 13% in the non-alcohol-related ESLD group (p <0.005). In the 2 groups, the presence of ≥1 CAD risk factor was associated with significant CAD (p <0.05 for all). Absence of cardiac risk factors was highly predictive in ruling out angiographically significant disease (negative predictive value 100% for alcohol-related ESLD and 97% for non-alcohol-related ESLD). DSE was performed in 205 patients. In the 2 groups, DSE had poor predictive value for diagnosing significant CAD but was useful in ruling out patients without significant disease (negative predictive value 89% for alcohol-related ESLD and 80% for non-alcohol-related ESLD). In conclusion, there was a significantly lower prevalence of severe CAD in patients with alcohol-related ESLD. These findings suggest that invasive coronary angiography may not be necessary in this subgroup, particularly in the absence of CAD risk factors and negative results on DSE.

Cardiovascular risk assessment of the liver transplant candidate

Liver transplantation (LT) candidates today are increasingly older, have greater medical acuity, and have more cardiovascular comorbidities than ever before. Steadily rising model for end-stage liver disease (MELD) scores at the time of transplant, resulting from high organ demand, reflect the escalating risk profiles of LT candidates. In addition to advanced age and the presence of comorbidities, there are specific cardiovascular responses in cirrhosis that can be detrimental to the LT candidate. Patients with cirrhosis requiring LT usually demonstrate increased cardiac output and a compromised ventricular response to stress, a condition termed cirrhotic cardiomyopathy. These cardiac disturbances are likely mediated by decreased beta-agonist transduction, increased circulating inflammatory mediators with cardiodepressant properties, and repolarization changes. Low systemic vascular resistance and bradycardia are also commonly seen in cirrhosis and can be aggravated by beta-blocker use. These physiologic changes all contribute to the potential for cardiovascular complications, particularly with the altered hemodynamic stresses that LT patients face in the immediate post-operative period. Post-transplant reperfusion may result in cardiac death due to a multitude of causes, including arrhythmia, acute heart failure, and myocardial infarction. Recognizing the hemodynamic challenges encountered by LT patients in the perioperative period and how these responses can be exacerbated by underlying cardiac pathology is critical in developing recommendations for the pre-operative risk assessment and management of these patients. The following provides a review of the cardiovascular challenges in LT candidates, as well as evidence-based recommendations for their evaluation and management.

Safety of regadenoson in patients with end-stage liver disease

BACKGROUND

Regadenoson is a selective A(2A) receptor agonist that is used for vasodilator stress myocardial perfusion imaging (MPI). Since the drug is partially metabolized by the liver, its safety in patients with end-stage liver disease (ESLD) needs to be determined.

METHODS AND RESULTS

We studied 168 consecutive patients with ESLD who had regadenoson stress gated single photon emission computed tomography MPI between January 2008 and March 2010 before planned orthotopic liver transplantation and compared the hemodynamic responses and safety profile to 168 control patients. There were 72 women (43%) in ESLD versus 87 (52%) in the control group (P = .1). The patients with ESLD were younger (58 ± 7 vs 62 ± 12 years, P = .0002), but more likely to be Caucasians (P = .002). The MPI images were normal in 161 patients (96%) in each group. The left ventricular ejection fraction was 72 ± 10% in ESLD and 66 ± 11% in the control patients (P = .0001). The heart rate increase in response to regadenoson was lower in patients with ESLD than in the control group (16 ± 11 vs 23 ± 16 bpm, P = .0001), but the changes in systolic and diastolic blood pressures were similar (-9 ± 12 vs -11 ± 14 mmHg and -6 ± 8 vs -7 ± 10 mmHg, respectively, P = NS). There were no deaths or medication-related adverse events that required hospitalization in either group within 30 days of the study.

CONCLUSION

This is the first study to document the tolerability and safety profile of regadenoson in patients with ESLD.

Coronary artery disease in orthotopic liver transplantation: pretransplant assessment and management

The prevalence of coronary artery disease in end-stage liver disease is only now being recognized. Liver transplant patients are a high risk subgroup for coronary artery disease, even if asymptomatic. Coronary artery disease is a predictor of poor outcomes; therefore, identification of those at risk must be a key clinical priority. However, risk assessment is particularly difficult as many of the available diagnostic tools have either proven to be unhelpful or remain to be validated. Risk factor profiling has been unable to identify those at risk and commonly underestimates risk. The high negative predictive value of Dobutamine stress echo, when target heart rates are achieved, allows it to be used to identify a low risk group. For all other patients, proceeding to invasive coronary angiography is often necessary, and the risks of the procedure can be reduced by a transradial approach. Pharmacological reduction of the consequences of coronary artery disease can be limited by the underlying liver disease. Revascularization pre-transplantation is recommended in international guidelines but has demonstrated little evidence of benefit. Surgical revascularization carries an increased risk in these patients and is commonly performed pre-transplantation, although combined liver and cardiac surgery has been described. Percutaneous coronary intervention is increasingly used with patients requiring anti-platelet medication for up to one year after intervention. We present a review of all these issues and the evidence for assessing and managing these high-risk patients.

Value of stress myocardial perfusion scanning in diagnosis of severe coronary artery disease in liver transplantation candidates

BACKGROUND

The significant potential for perioperative and late cardiovascular complications makes careful preoperative cardiac risk assessment imperative in liver transplantation candidates.

OBJECTIVE

To determine the sensitivity and specificity of myocardial perfusion scanning for detection of coronary artery disease (CAD) in liver transplantation candidates.

PATIENTS AND METHODS

We prospectively evaluated 93 liver transplantation candidates. Patients with known CAD were excluded. All patients, regardless of symptoms and risk factors, underwent myocardial perfusion scanning and coronary angiography.

RESULTS

Results of myocardial perfusion scanning were abnormal in 64 patients (68.8%) and normal in 29 patients (31.2%). Of patients with abnormal scans, only 6 (9.4%) had severe CAD at coronary angiography. None of the 29 patients with normal perfusion scans and the 24 patients with fixed defects had severe CAD; however, 6 of 40 patients (15.0%) with reversible perfusion defects had severe CAD at coronary angiography (P = .005). Alcoholic liver disease, reversible perfusion defects at myocardial perfusion scanning, left ventricular systolic dysfunction, and higher low-density lipoprotein (LDL) cholesterol and triglyceride levels were significantly associated with CAD. Defining reversible perfusion defects as a sign of ischemia, and fixed defects and normal perfusion as nonischemic, myocardial perfusion scanning had 100% sensitivity but 61% specificity for severe CAD. The test's accuracy was low (38%).

CONCLUSIONS

The results of reversible perfusion defects on myocardial perfusion scanning were sensitive but not specific for CAD in liver transplantation candidates. The high number of false-positive results decreased the test's accuracy.

Liver transplantation: from Child to MELD

The widespread availability of transplantation in most major medical centers in the United States, together with a growing number of transplant candidates, has made it necessary for primary care providers, especially internal medicine and family practice physicians to be active in the clinical care of these patients before and after transplantation. This review provides an overview of the liver transplantation process, including indications, contraindications, time of referral to a transplant center, the current organ allocation system, and briefly touches on the expanding field of living donor liver transplantation.

Influence of coronary artery disease on outcomes after liver transplantation

Patients with coronary artery disease (CAD) who undergo liver transplantation (OLT) have been previously identified as a high-risk group. Since that identification, the management of CAD has undergone significant changes as has the cardiovascular screening and selection of patients for OLT. We retrospectively identified 42 patients with known CAD who underwent OLT to compare outcomes with a control group of 42 patients without CAD who were matched for gender, age, and primary liver disease. Mortality rates were higher in the CAD than the control group at 1 year (5 vs 1) and 3 years (11 vs 3; P < .05) although lower than previously reported (at 3 years, 26% vs 50%). New cardiovascular morbidity was also more frequent among the CAD than control group at 1 year (11 vs 3; P < .05) and 3 years (16 vs 4; P < .05). Although outcomes for patients with CAD undergoing OLT are improved from historical levels, they are still worse than those in patients without CAD despite current management and selection strategies.

Prevalence of coronary artery calcification in patients undergoing assessment for orthotopic liver transplantation

Patients with advanced liver disease are at increased risk of cardiovascular events, especially following orthotopic liver transplantation (OLT). Coronary artery calcification (CAC) is a novel and independent predictor of cardiovascular risk, but its prevalence and utility in patients with cirrhosis are unknown. The aim of this study was to define the prevalence of CAC and its association with markers of disease severity and standard measures of cardiovascular risk in a large cohort of patients undergoing OLT assessment. A single-center, prospective, observational study of 147 consecutive patients undergoing assessment for OLT was performed. CAC scores were derived with the Agatston method from thoracic computed tomography scans and correlated with cardiovascular risk factors and measures of liver disease severity. There were 101 patients (66 males) with a mean age of 53.2 years; 46 patients were excluded because the CAC score was not reported. The median CAC score was 40 HU (range, 0-3533). Correlations were identified between the CAC score and age (r = 0.477; P < 0.001), male sex (r = 0.262; P = 0.008), family history of cardiovascular disease (r = 0.208; P = 0.036), Framingham risk score (r = 0.621; P < 0.001), Model for End-Stage Liver Disease score (r = 0.221; P = 0.027), systolic blood pressure (r = 0.285; P = 0.004), diastolic blood pressure (r = 0.267; P = 0.007), cytomegalovirus status (r = 0.278; P = 0.005), fasting glucose (r = 0.330; P = 0.001), number of coronary vessels involved (r = 0.899; P < 0.001), and components of the metabolic syndrome (r = 0.226; P = 0.026). After multivariate analysis, age, systolic blood pressure, fasting glucose, number of features of metabolic syndrome, and number of vessels involved remained significantly associated with CAC. In conclusion, this study identified a high prevalence of occult coronary artery disease in patients undergoing OLT assessment and identified a strong relationship between CAC scores and a limited number of specific cardiovascular risk factors. The usefulness of these factors in predicting perioperative and postoperative cardiovascular events in patients undergoing OLT requires prospective evaluation.

The liver transplant recipient with cardiac disease

Liver transplantation is a stressful condition for the cardiovascular system of patients with advanced hepatic disease. The underlying hemodynamic and cardiac status of patients with cirrhosis is crucial to determine which patients should became recipients. Generally preoperative cardiovascular testing is performed on potential candidates who are more than 45 years old, or have diabetes mellitus, or peripheral vascular disease, or more than two standard cardiac risk factors. Recent data suggest that the prevalence of coronary artery disease among patients with cirrhosis is much greater than previously believed; it likely mirrors or exceeds the prevalence rate in the healthy population. The morbidity and mortality of patients with coronary artery disease who undergo orthotopic liver transplantation (OLT) without treatment are unacceptably high. In conclusion, accurate preoperative cardiac evaluation according to the new American Heart Association & American College of Cardiology should lead to detect and treat coronary artery disease before liver transplantation. In case of alcohol-related cardiomyopathy, portopulmonary hypertension, and hypertrophic cardiomyopathy, there should be a case-by-case discussion by the hepatologist and cardiologist to consider the patient for liver transplantation. No robust data are available on the impact of decompensated dilated heart failure in this setting. If a recipient with cardiac disease is scheduled for OLT, we strongly suggest advanced intra- and postoperative hemodynamic monitoring plus transesophageal echocardiography.

Metabolic syndrome in liver transplant recipients: prevalence and association with major vascular events

Cardiac and cerebral vascular diseases are leading causes of morbidity and death in solid organ transplant recipients. Immunosuppressant drugs are associated with dyslipidemia, hypertension, and hyperglycemia, which along with obesity are the main features of metabolic syndrome. In the nontransplant population, metabolic syndrome is associated with increased risk for major vascular complications. We postulated that metabolic syndrome is common post-liver transplantation and plays a significant role leading to cardiac and cerebrovascular events. Our Multi-Organ Transplant Program database was reviewed for all liver transplant recipients between January 1998 and June 2004 with follow-up until December 2005. We adapted the 2001 National Cholesterol Education Program-Adult Treatment Panel III Guidelines to define posttransplantation metabolic syndrome (PTMS) as the presence at least 3 of the following: 1) obesity (body mass index>30 kg/m2); 2) serum triglyceride level>or=1.7 mmol/L; 3) high density lipoprotein level<1 mmol/L in men and <1.3 mmol/L in women; 4) hypertension; and 5) fasting plasma glucose>or=5.6 mmol/L. A total of 118 patients were included. Among them, 69 patients (58%) had PTMS. The mean (+/-standard deviation) time from transplant was 59+/-21 months (no significant difference in patients with or without metabolic syndrome). Overall, patients with metabolic syndrome had a significantly higher average age, posttransplantation body mass index, fasting glucose, high-density lipoprotein levels, and serum triglycerides. There was no difference in creatinine, hemoglobin, or prednisone average dose between the 2 groups. There were 25 major vascular events affecting 21% of patients. There were significantly more vascular events in patients with metabolic syndrome posttransplantation than in those without (30% vs. 8%; P=0.003) during the study period. In conclusion, the prevalence of metabolic syndrome post-liver transplant is significantly higher than that estimated in the general population. Metabolic syndrome appears to be associated with an increased risk of major vascular events in our liver transplant population.

Current indications and contraindications for liver transplantation

Survival rates after liver transplantation have improved steadily because of earlier referral and timely evaluation, judicious patient selection, improved surgical techniques, superior immunosuppressive regimens, and effective prevention of perioperative opportunistic infections. Indications and contraindications for liver transplantation are undergoing constant modifications with the goal of improving survival and functional status of patients who have end-stage liver disease or acute liver failure. Potential candidates for liver transplantation should meet minimal listing criteria and not have contraindications to liver transplantation. Currently, the Model for End-stage Liver Disease score is used for organ allocation, but it may have future application in patient-selection criteria.

Cirrhotic cardiomyopathy

Cirrhotic cardiomyopathy is the term used to describe a constellation of features indicative of abnormal heart structure and function in patients with cirrhosis. These include systolic and diastolic dysfunction, electrophysiological changes, and macroscopic and microscopic structural changes. The prevalence of cirrhotic cardiomyopathy remains unknown at present, mostly because the disease is generally latent and shows itself when the patient is subjected to stress such as exercise, drugs, hemorrhage and surgery. The main clinical features of cirrhotic cardiomyopathy include baseline increased cardiac output, attenuated systolic contraction or diastolic relaxation in response to physiologic, pharmacologic and surgical stress, and electrical conductance abnormalities (prolonged QT interval). In the majority of cases, diastolic dysfunction precedes systolic dysfunction, which tends to manifest only under conditions of stress. Generally, cirrhotic cardiomyopathy with overt severe heart failure is rare. Major stresses on the cardiovascular system such as liver transplantation, infections and insertion of transjugular intrahepatic portosystemic stent-shunts (TIPS) can unmask the presence of cirrhotic cardiomyopathy and thereby convert latent to overt heart failure. Cirrhotic cardiomyopathy may also contribute to the pathogenesis of hepatorenal syndrome. Pathogenic mechanisms of cirrhotic cardiomyopathy are multiple and include abnormal membrane biophysical characteristics, impaired β-adrenergic receptor signal transduction and increased activity of negative-inotropic pathways mediated by cGMP. Diagnosis and differential diagnosis require a careful assessment of patient history probing for excessive alcohol, physical examination for signs of hypertension such as retinal vascular changes, and appropriate diagnostic tests such as exercise stress electrocardiography, nuclear heart scans and coronary angiography. Current management recommendations include empirical, nonspecific and mainly supportive measures. The exact prognosis remains unclear. The extent of cirrhotic cardiomyopathy generally correlates to the degree of liver insufficiency. Reversibility is possible (either pharmacological or after liver transplantation), but further studies are needed.

Cardiac hemodynamic and coronary angiographic characteristics of patients being evaluated for liver transplantation

With improved survival after liver transplantation (LT), the referral of older candidates has increased. The increasing demand for, and the decreased supply of, liver donors makes careful preoperative cardiac risk assessment imperative. There is a paucity of information regarding the cardiac characteristics of patients being referred for LT in the current era. This study aimed to describe the cardiac hemodynamic and coronary angiographic characteristics of a cohort of patients with end-stage liver disease without known coronary artery disease (CAD) being evaluated for LT. One hundred sixty-one consecutive patients aged>or=45 years with end-stage liver disease who were referred for right- and left-sided cardiac catheterization as part of a liver transplant evaluation were identified. There was a high prevalence of atherosclerotic risk factors; half had hypertension or diabetes, and more than half had >or=2 coronary risk factors other than age. There was a high prevalence of CAD, with 26% having unknown moderate to severe coronary narrowing. Patients with moderate to severe CAD were older, were more likely to be men, and were more likely to have hypertension or diabetes mellitus. Right- and left-sided filling pressures were elevated, suggesting abnormalities in left ventricular diastolic compliance. In conclusion, this study showed a high prevalence of coronary risk factors and unknown moderate to severe CAD in patients with end-stage liver disease being referred for LT.

Value of dobutamine stress myocardial contrast perfusion echocardiography in patients with advanced liver disease

Although dobutamine stress echocardiography has been used for the preoperative evaluation of patients with advanced liver disease (ALD), no data exist regarding the value of myocardial perfusion imaging (MPI) with real-time myocardial contrast echocardiography (RTMCE) in this patient population. We sought to determine the value of MPI during dobutamine stress RTMCE for predicting prognosis in patients with ALD. We examined both wall motion and MPI in 230 patients with ALD who underwent dobutamine stress RTMCE using intravenous commercially available contrast agents (Optison, GE-Amersham, Princeton, NJ; or Definity, Bristol-Myers Squibb Medical Imaging, North Billerica, MA). The prognostic value of clinical variables, including the Model for End-Stage Liver Disease (MELD) score, and echocardiographic data were examined using a Cox Hazard model. The primary endpoint was mortality of all causes. Among the 85 patients who underwent orthotopic liver transplantation, 4 had abnormal MPI and 81 had normal perfusion. The hospital mortality rate was 50% (2/4) in patients with abnormal MPI and 2% (2/81) in patients with normal MPI (P = 0.01). Among patients with abnormal MPI, 1 died from myocardial infarction in the first postoperative day and the second 1 from hemorrhagic shock. During a median follow-up of 15 months, 53 (23%) patients died. The independent predictors of death were an age of > or = 65 yr (RR = 2.2; 95% confidence interval (CI) = 1.1-4.4; P = 0.03), MELD score of > or = 25 (RR = 3.2; 95% CI = 1.8-5.5; P < 0.0001), and abnormal MPI (RR = 2.4; 95% CI = 1.1-5.2; P = 0.02). The 2-yr mortality was 24% for patients with normal MPI and 45% for those with inducible MPI abnormalities (P = 0.003). In conclusion, MPI obtained by RTMCE appears to be a useful tool in predicting mortality in patients with ALD. Further studies are required to verify its independent value.

Sinus arrest during adenosine stress testing in liver transplant recipients with graft failure: three case reports and a review of the literature

BACKGROUND

Nuclear stress imaging is used frequently to evaluate patients with end-stage liver disease who are being considered for orthotopic liver transplantation.

METHODS AND RESULTS

We present three patients who, following graft failure, developed sinus arrest during adenosine stress testing performed in anticipation of repeat liver transplantation. All had undergone uneventful adenosine stress imaging prior to initial transplantation. The mechanisms of action, pharmacokinetics, and pharmacodynamics of adenosine are reviewed, and possible reasons for this phenomenon are discussed. Finally, cautions regarding the use of adenosine and treatment of adenosine-induced sinoatrial and atrioventricular block are reviewed.

CONCLUSION

Adenosine should be used with caution in patients following orthotopic liver transplantation due to an increased risk of sinus arrest. Should sinus arrest or atrioventricular block occur, it appears to respond readily to cessation of adenosine infusion and intravenous aminophylline with no significant sequelae.

Plasma total homocysteine and cardiovascular risk in patients submitted to liver transplantation

Patients submitted to orthotopic liver transplantation (OLT) show an increased rate of cardiovascular events. OLT subjects have high homocysteine (Hcy) levels, but no data are available on the association of Hcy with cardiovascular events. In a cross-sectional analysis, 230 subjects were studied at least 6 months after OLT (159 on cyclosporine, 71 on tacrolimus). Routine laboratory data and total Hcy were recorded, as well as the history of diabetes, hypertension, dyslipidemia, and overweight. Cardiovascular events occurring in a follow-up of 2-36 months were registered. OLT subjects had higher-than-normal Hcy (median 16.7 micromol/L, range 6.1-171.8) without difference between the 2 immunosuppressive agents. The prevalence of Hcy >15 micromol/L was also similar, and significantly correlated with creatinine levels. A total of 28 arterial events occurred in 25 patients during follow-up (11 in coronary arteries, 10 in peripheral arteries, and 7 in splanchnic arteries). Deep vein thromboses occurred in 2 patients, and splanchnic vein thromboses in 4 patients. Cardiovascular events were frequently associated to high Hcy and hypertension. Cox regression analysis showed that high Hcy was significantly associated with arterial events. The risk of any arterial event, coronary artery or peripheral artery event increased by nearly 10% for any increase in Hcy of 5 micromol/L. In conclusion, high Hcy may be involved in the pathogenesis of cardiovascular events in OLT patients. The usefulness of Hcy-lowering therapy remains to be verified.

Anesthesia for liver transplant surgery

Liver transplantation offers patients with liver disease an optimal chance for long-term survival. Current indications, preoperative assessment, patient selection, intraoperative anesthetic management and outcomes are described. The management of special situations, including retransplantation, pediatric transplantation, and fulminant hepatic failure are also reviewed. The success of liver transplantation has led to increased demand. This demand, coupled with a nonexpanding supply of deceased donor organs, has resulted in a shortage of grafts and prolonged waiting times. Novel solutions using segmental liver grafts from living donors, and the challenges associated with this approach, are discussed.

The transplant recipient for nontransplant surgery

The transplant recipient has traded a life-threatening illness for a chronically immunosuppressed state. Subsequent anesthetic management for non-transplant surgical procedures may be challenging. The anesthesia provider must be aware of the degree of post-transplant organ dysfunction and alter anesthesia techniques accordingly. This article reviews the anesthetic concerns for patients who have undergone a variety of organ transplants.

MELD and other factors associated with survival after liver transplantation

Allocation of cadaveric livers for transplantation in the United States is now based on the severity of illness as determined by the model for end-stage liver disease (MELD) score, a function of bilirubin, creatinine and international normalized ratio (INR). The aim of our study was to determine the association of various pre-transplant risk factors, including the MELD score, on patient survival after orthotopic liver transplantation (OLT). The medical records of 499 consecutive patients (233 female, 266 males, mean age 50.9 +/- 10.6 years) undergoing cadaveric OLT at our institution between June 1990 and February 1998 were reviewed. In the 407 patients alive at the latest contact, follow-up was 4.7 years, with a minimum of 20 months (maximum of 9.4 years). Variables considered for analysis included MELD score, age, pre-transplant renal dysfunction requiring dialysis, Child-Pugh classification, underlying liver disease, diabetes mellitus, and heart disease (ischemic/valvular/other). There were 92 deaths during follow-up. In univariate analysis, the MELD score, renal failure requiring hemodialysis pre-OLT, age > 42 years, and underlying etiology of liver disease were significantly associated with death during long-term follow-up. In multivariate models, age, underlying etiology of liver disease and renal failure requiring hemodialysis were independent predictors of death after OLT.

Usefulness of preoperative stress perfusion imaging in predicting prognosis after liver transplantation

The role of preoperative stress single-photon emission computed tomographic (SPECT) imaging in patients with end-stage liver disease who underwent liver transplantation is not well established. We reviewed medical records of patients who had liver transplantation at our institution between January 1998 and November 2001. During this time, 339 patients (213 men, aged 51 +/- 11 years) underwent liver transplantation. Of these, 87 patients had preoperative stress SPECT imaging. Diabetes mellitus (30% vs 11%), hypertension (26% vs 12%), and coronary artery disease (15% vs 7%) were more prevalent in those with than without SPECT (p <0.01 each). The stress SPECT perfusion images were normal in 78 patients (91%) and the left ventricular ejection fraction was 72 +/- 10%. SPECT images revealed ascites in 66% and splenomegaly in 83% of patients. There were 35 total deaths (10%) and 5 nonfatal myocardial infarctions over a mean follow-up of 21 +/- 13 months. Most deaths (32 of 35) were noncardiac and sepsis was the most common cause of death. A normal SPECT study had a 99% negative predictive value for perioperative cardiac events. Kaplan-Meier survival curves showed an 87% 2-year cumulative survival rate in the total group. Thus, in patients undergoing liver transplantation, 2-year survival depends on early noncardiac events. A normal stress SPECT study identified patients at a very low risk for early and late cardiac events despite a higher risk profile. SPECT images also revealed unique findings, such as ascites and splenomegaly, which could produce image artifacts and may interfere with accurate image interpretation.

Immunosuppression impact on long-term cardiovascular complications after liver transplantation

BACKGROUND

With current early transplant patient and allograft survivals nearly optimized, long-term medical complications have become a significant focus for potential improvement in patient outcomes. Cardiovascular disease and associated risk factors have been shown in renal transplant patients to be related to the pharmacologic immunosuppression employed.

OBJECTIVE

The objective of this study is to investigate at 3 years postliver transplant (OLTx) the incidence of hypertension (HTN), hyperlipidemia (HLIP), diabetes mellitus (DM), nephrotoxicity (NTX), and cardiovascular disease (MI, angioplasty, CHF, CVA, and seborth) as well as rejection in two cohorts of liver transplant recipients who received either tacrolimus (FK-506) or cyclosporine (CSA) and to analyze the consequences of these complications on mortality following transplantation.

METHODS

Eighty-seven sequential patients (CSA: n = 50, mean age 48 years, M/F 32/18; and FK-506: n = 37, mean age 45 years, M/F 22/15) who underwent OLTx between 1994 and 1998, were >/=18 years, and had a minimum of 3 years of complete follow-up were included in the analysis. All OLTx candidates over age 50, who had a history of alcoholic cirrhosis, or had a history of cardiac conditions/events underwent complete cardiac consultation including an echocardiogram with additional cardiac investigation as indicated prior to OLTx.

RESULTS

At 3 years following OLTx, the incidence of acute rejection (40% versus 19%, P < 0.05), HTN (62% versus 38%, P < 0.05), HLIP (14% versus 5%, P = 0.08), and cardiovascular disease (18% versus 0%, P < 0.001), were significantly greater for the CSA patients compared with the FK-506 patients. Eight (20%) of the CSA patients who died before 3 years had their death attributed to cardiovascular events versus none in the FK-506 group.

CONCLUSION

Compared with CSA, FK-506 was associated with significantly less rejection and a reduced incidence of HTN and cardiovascular disease.

Critical care of the liver transplant patient: an update

The unique pathophysiology of patients with end-stage liver disease has important implications for their critical care treatment, particularly in the postoperative state. To gauge hemodynamic parameters and responses, each patient must be carefully evaluated for their place in the clinical spectrum of cirrhosis and portal hypertension. Although the data are limited, the biology of the consequences of liver disease is emphasized by novel treatments of hepatorenal syndrome, portopulmonary hypertension, and hepatopulmonary syndrome. These issues become more relevant with increased adult-to-adult living donor liver transplantation, in which technical considerations may further complicate the general treatment of the postoperative transplant patient.