Dobutamine stress echocardiography for orthotopic liver transplant evaluation

Predictive Value of Dobutamine Stress Perfusion Echocardiography in Contemporary End-Stage Liver Disease

BACKGROUND

The assessment of cardiac risk in contemporary liver transplantation (LT) has required more sensitive testing for the detection of occult coronary artery disease as well as microvascular and functional cardiac abnormalities. Because dobutamine stress perfusion echocardiography provides an assessment of both regional systolic and diastolic function as well as microvascular perfusion (MVP), we sought to examine its incremental value in this setting.

METHODS AND RESULTS

We evaluated the predictive value of dobutamine stress perfusion echocardiography in 296 adult patients with end-stage liver disease and preserved systolic function who underwent LT between 2008 and 2014. The primary outcome was cardiovascular death, nonfatal myocardial infarction, and/or sustained ventricular arrhythmias following LT. The main causes of liver failure were hepatitis C (25%) and nonalcoholic fatty liver disease (13%). Abnormal MVP during stress was observed in 18 patients (6%), whereas diastolic dysfunction was present in 109 patients (94 grade 1, 15 grade 2). Half of the patients (7 of 14) referred for angiography with abnormal MVP had significant epicardial disease by angiography, and these patients were revascularized prior to LT. Despite these interventions, the primary outcome still occurred in 9 patients (3%). Patients with abnormal MVP during dobutamine stress perfusion echocardiography had a 7-fold higher risk of a cardiovascular event following LT. Cox proportional hazards modeling examining clinical variables, left ventricular ejection fraction, diastolic function, and stress-induced wall motion abnormalities or MVP defects demonstrated that abnormal MVP was the only independent predictor of the primary outcome (P=0.004; hazard ratio 7.7).

CONCLUSIONS

Stress MVP assessments are highly predictive of cardiovascular outcome in current LT candidates.

New index for assessing the chronotropic response in patients with end-stage liver disease who are undergoing dobutamine stress echocardiography

The inability to achieve 85% of the maximum predicted heart rate (MPHR) on dobutamine stress echocardiography (DSE) is defined as chronotropic incompetence and is a predictor of major cardiac events after orthotopic liver transplantation (OLT). The majority of patients with end-stage liver disease (ESLD) receive beta-blockers for the prevention of variceal bleeding. In these patients, it is impossible to determine whether chronotropic incompetence is secondary to cirrhosis-related autonomic dysfunction or is merely a beta-blocker effect. We evaluated the usefulness of the maximum achieved heart rate (MAHR) and the heart rate reserve (HRR) in the detection of chronotropic incompetence in ESLD patients on beta-blocker therapy before DSE. We also evaluated the usefulness of a new index, the modified heart rate reserve (MHRR), in diagnosing chronotropic incompetence and predicting major cardiovascular adverse events after OLT. The study population consisted of 284 ESLD patients. The mean values of MAHR (expressed as a percentage of 85% of MPHR) and HRR were significantly lower for patients on beta-blockers versus patients off beta-blockers [97.1% versus 101.6% (t = 5.01, P < 0.001) and 71.7% versus 77.3% (t = 4.03, P < 0.001), respectively], whereas the values of MHRR were similar in patients on beta-blockers and patients off beta-blockers [102.3% versus 102.1% (t = 0.04, P = 0.97)]. A regression analysis showed a significant association of MAHR (P < 0.001) and HRR (P < 0.001) with beta-blockers, whereas MHRR was not associated with beta-blocker treatment (P = 0.92). MAHR and HRR were found to have no value for diagnosing chronotropic incompetence in ESLD patients. MHRR was not affected by beta-blocker therapy. Patients who developed heart failure (HF) and myocardial infarction (MI) after OLT had significantly lower MHRR values according to pretransplant DSE. MHRR was significantly associated with the subsequent development of HF (P = 0.01) and MI (P = 0.01) after OLT. MHRR may be useful for the determination of the target heart rate for stress testing, the diagnosis of chronotropic incompetence, and the prediction of adverse cardiac events after OLT.

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.

Cardiovascular abnormalities in special conditions of advanced cirrhosis. The circulatory adaptative changes to specific therapeutic procedures for the management of refractory ascites

Advanced liver disease is characterized by decreased arterial blood pressure and peripheral vascular resistances, increased cardiac output and heart rate in the setting of a hyperdynamic circulatory pattern favoured by total blood volume expansion, circulatory overload and overactivity of the endogenous vasoactive systems. Reduced heart responses to stressful conditions such as changes in loading conditions of the heart in presence of further deterioration of liver function such as refractory ascites, hepatorenal syndrome, spontaneous bacterial peritonitis and bleeding esophageal varices have been recently identified and the knowledge of the cirrhotic cardiomyopathy syndrome has gained the dignity of a new clinical entity. Facing the availability of therapeutic interventions (paracentesis, transjugular intrahepatic portosystemic shunt, peritoneovenous shunt, orthotopic liver transplantation) currently employed to manage the life-threatening complications of the most advanced phases of cirrhotic disease, the knowledge of their impact on cardiovascular function is of paramount relevance.

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.

A Meta-Analytic Comparison of Preoperative Stress Echocardiography and Nuclear Scintigraphy Imaging

In this meta-analysis we compared thallium imaging (TI) and stress echocardiography (SE) in patients at risk for myocardial infarction (MI) scheduled for elective noncardiac surgery. Two searches of published articles were used to identify relevant articles. We included all studies that stated the criteria for a positive test and detailed the frequency of postoperative MI and in-hospital death. Data were abstracted by two authors and captured preoperative patient characteristics, study design, blinding, and outcome adjudication. We defined a positive test as a test with a reversible defect and, where possible, quantified the size of the defects in each study. MI and/or death were the only postoperative outcomes of interest. We calculated the sensitivity, specificity, and likelihood ratio (LR) and, where possible, the Receiver Operating Characteristic (ROC) curve of a cardiac event in each study. The LR and ROC were combined by meta-analyses using the random effects model. Heterogeneity was assessed using the I2 test. The search revealed 68 studies of 10,049 patients. There were 25 SE studies and 50 TI studies. There were 7 studies with a direct comparison of the two methodologies. The quality of studies differed; routine screening for MI was used more frequently in SE studies (47.8% versus 21.2%; P = 0.008) and screening dictated treatment more often after TI (72.1%) than after SE (46.3%) (P = 0.027). The LR for SE was more indicative of a postoperative cardiac event than TI (LR, 4.09; 95% CI, 3.21-6.56 versus 1.83; 1.59-2.10; P = 0.001). This difference was attributable to fewer false-negative SEs. There was no difference in the cumulative ROC curves from qualitative studies (SE, 0.80; 95% CI, 0.76-.84 versus TI, 0.75; 95% CI, 0.70-081). Again, the LR for a negative SE was less (0.23; 95% CI, 0.17-0.32 versus 0.44; 95% CI, 0.36-0.54). A moderate-to-large defect, seen in 14% of patients, by either method predicts a postoperative cardiac event (LR, 8.35; 95% CI, 5.6-12.45). This meta-analysis possesses the statistical power to demonstrate that SE has better negative predicative characteristics than TI. A moderate-to-large perfusion defect by either SE or TI predicts postoperative MI and death. We conclude the SE is superior to TI in predicting postoperative cardiac events.

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.