Utility of preoperative troponin I to predict mortality in adult liver transplant recipients: Revisiting pretransplant cardiac risk in the current MELD-allocation era.

BACKGROUND: Preoperative risk assessment in liver transplant (LT) candidates, particularly related to cardiac risk, is an area of intense interest for transplant clinicians. Various cardiac testing methods are employed by transplant centers to characterize cardiac risk. Serum troponin is an established method for the detection of myocardial injury in a wide variety of clinical settings. Preoperative troponin screening has been reported to predict postoperative cardiac events and mortality in various surgical patient populations, however, the utility of preoperative troponin to predict posttransplant outcomes in current LT candidate populations requires further investigation. METHODS: We performed a prospective blinded study in a cohort of 275 consecutive LT recipients at a single transplant center to determine if preoperative serum troponin I (TnI) was predictive for postoperative 1-year mortality. RESULTS: Abnormal preoperative TnI levels (>.1 ng/mL) were found in 38 patients (14%). One-year mortality occurred in 19 patients (7%). There was no significant difference in mortality between patients with normal and abnormal troponin levels. Additionally, we found that there was no significant difference in early postoperative major adverse cardiac events between patient groups. CONCLUSIONS: Contrary to previous reports, elevated preoperative TnI was not significantly predictive of posttransplant mortality in LT recipients at our institution.

Regional Left Ventricular Myocardial Dysfunction After Cardiac Surgery Characterized by 3-Dimensional Strain.

BACKGROUND: Three-dimensional (3D) strain is an echocardiographic modality that can characterize left ventricular (LV) function with greater accuracy than ejection fraction. While decreases in global strain have been used to predict outcomes after cardiac surgery, changes in regional 3D longitudinal, circumferential, radial, and area strain have not been well described. The primary aim of this study was to define differential patterns in regional LV dysfunction after cardiac surgery using 3D speckle tracking strain imaging. Our secondary aim was to investigate whether changes in regional strain can predict postoperative outcomes, including length of intensive care unit stay and 1-year event-free survival. METHODS: In this prospective clinical study, demographic, operative, echocardiographic, and clinical outcome data were collected on 182 patients undergoing aortic valve replacement, mitral valve repair or replacement, coronary artery bypass graft, and combined cardiac surgery. Three-dimensional transthoracic echocardiograms were performed preoperatively and on the second to fourth postoperative day. Blinded analysis was performed for LV regional longitudinal, circumferential, radial, and area strain in the 17-segment model. RESULTS: Regional 3D longitudinal, circumferential, radial, and area strains were associated with differential patterns of myocardial dysfunction, depending on the surgical procedure performed and strain measure. Patients undergoing mitral valve repair or replacement had reduced function in the majority of myocardial segments, followed by coronary artery bypass graft, while patients undergoing aortic valve replacement had reduced function localized only to apical segments. After all types of cardiac surgery, segmental function in apical segments was reduced to a greater extent as compared to basal segments. Greater decrements in regional function were seen in circumferential and area strain, while smaller decrements were observed in longitudinal strain in all surgical patients. Both preoperative regional strain and change in regional strain preoperatively to postoperatively were correlated with reduced 1-year event-free survival, while postoperative strain was not predictive of outcomes. Only preoperative strain values were predictive of intensive care unit length of stay. CONCLUSIONS: Changes in regional myocardial function, measured by 3D strain, varied by surgical procedure and strain type. Differences in regional LV function, from presurgery to postsurgery, were associated with worsened 1-year event-free survival. These findings suggest that postoperative changes in myocardial function are heterogeneous in nature, depending on the surgical procedure, and that these changes may have long-term impacts on outcome. Therefore, 3D regional strain may be used to identify patients at risk for worsened postoperative outcomes, allowing early interventions to mitigate risk.

Preoperative Three-Dimensional Strain Imaging Identifies Reduction in Left Ventricular Function and Predicts Outcomes After Cardiac Surgery.

BACKGROUND: Echocardiography-based speckle-tracking strain imaging is an emerging modality to assess left ventricular function. The aim of this study was to investigate the change in left ventricular systolic function after cardiac surgery with 3-dimensional (3D) speckle-tracking strain imaging and to determine whether preoperative 3D strain is an independent predictor of acute and long-term clinical outcomes after aortic valve, mitral valve, and coronary artery bypass grafting operations. METHODS: In total, 163 adult patients undergoing aortic valve, mitral valve, and coronary artery bypass surgeries were enrolled prospectively and had complete data sets. Demographic, operative, and outcome data were collected. 3D transthoracic echocardiograms were preformed preoperatively and on second to fourth postoperative day. Blinded off-line analysis was performed for left ventricular 2-dimensional (2D) ejection fraction (EF2D) and 3D ejection fraction (EF3D) and global peak systolic area, longitudinal, circumferential, and radial strain. RESULTS: 3D global strain correlated well with EF3D. Ventricular function as measured by strain imaging decreased significantly after all types of cardiac surgery. When preoperative EF3D was used, receiver operating characteristic curves identified reference values for 3D global strain corresponding to normal, mildly reduced, and severely reduced ventricular function. Normal ventricular function (EF3D ≥ 50%) corresponded to 3D global area strain -25%, with area under curve = 0.86 (0.81-0.89). Patients with reduced preoperative 3D global area strain had worse postoperative outcomes, including length of intensive care unit stay (4 vs 3 days, P = .001), major adverse events (27% vs 11%, P = .03), and decreased 1-year event-free survival (69% vs 88%, P = .005). After we controlled for baseline preoperative risk models including European System for Cardiac Operative Risk Evaluation score and surgery type, preoperative strain was an independent predictor of both short- and long-term outcomes, including length of intensive care unit stay, postoperative inotrope score, and 1-year event-free survival. CONCLUSIONS: This study shows that cardiac surgery was associated with an acute reduction in postoperative left ventricular function, when evaluated with 3D strain imaging. In addition, preoperative 3D strain was demonstrated to be an independent predictor of acute and long-term clinical outcomes after cardiac surgery. The use of noninvasive 3D transthoracic echocardiogram strain imaging before cardiac surgery may provide added information to aid in perioperative risk stratification and management for these high-risk patients.

Increased red blood cell transfusions are associated with worsening outcomes in pediatric heart transplant patients.

BACKGROUND: Red blood cell (RBC) transfusions are associated with increased morbidity. Children receiving heart transplants constitute a unique group of patients due to their risk factors. Although previous studies in nontransplant patients have focused primarily on the effects of postoperative blood transfusions, a significant exposure to blood occurs during the intraoperative period, and a larger percentage of heart transplant patients require intraoperative blood transfusions when compared with general cardiac surgery patients. We investigated the relationship between clinical outcomes and the amount of blood transfused both during and after heart transplantation. We hypothesized that larger amounts of RBC transfusions are associated with worsening clinical outcomes in pediatric heart transplant patients. METHODS: A database comprising 108 pediatric patients undergoing heart transplantation from 2004 to 2010 was queried. Preoperative and postoperative clinical risk factors, including the amount of blood transfused intraoperatively and 48 hours postoperatively, were analyzed. The outcome measures were length of hospital stay, duration of tracheal intubation, inotrope score, and major adverse events. Bivariate and multivariate analyses were performed to control for simultaneous risk factors and determine outcomes in which the amount of blood transfused was an independent risk factor. RESULTS: Ninety-four patients with complete datasets were included in the final analysis. Eighty-eight percent received RBC transfusions, with a median transfusion amount of 38.7 mL/kg. A multivariate analysis correcting for 8 covariate risk factors, including the Index for Mortality Prediction After Cardiac Transplantation, age, weight, United Network for Organ Sharing status, warm and cold ischemia time, repeat sternotomy, and pretransplant hematocrit, showed RBC transfusions were independently associated with increased length of intensive care unit stay (means ratio = 1.34; 95% confidence interval, 1.03-1.76; P = 0.03), and increased inotrope score in the first postoperative 24 hour (mean ratio = 1.26; 95% confidence interval, 1.04-1.52; P = 0.04). Patients suffering major adverse events received significantly larger median amounts of blood RBC transfusions (P = 0.002). Transfusions >60 mL/kg were also associated with increased risk of major adverse events (accuracy 76%) including postoperative sepsis, extracorporeal membrane oxygenation, open chest, dialysis, and graft failure. CONCLUSION: The majority of pediatric patients undergoing orthotropic heart transplantation receive RBC transfusions, with the largest amount transfused in the operating room. Escalating amounts of RBC transfusions are independently associated with increased length of intensive care unit stay, inotrope scores, and major adverse events. Since heart allografts are a limited resource, improvement in the blood transfusion and conservation practices can enhance clinical outcomes in pediatric heart transplant patients.

Transthoracic echocardiography simulation is an efficient method to train anesthesiologists in basic transthoracic echocardiography skills.

BACKGROUND: The clinical utility of focused transthoracic echocardiography (TTE) is increasingly recognized in perioperative medicine. However its use is limited among anesthesiologists because of a lack of training. The most efficient training methods have not been determined. We hypothesized that simulation-based TTE training would be more effective than traditional lecture-based methods for teaching basic TTE skills to the anesthesiology residents. METHODS: In this prospective randomized study, 61 anesthesiology residents (in anesthesia clinical training years 1 to 3) were randomized to either control (n = 30) or simulation groups (n = 31) for TTE training. A standardized pretest was administered before TTE training sessions of 45 minutes each. The first training session used a lecture-based video didactic in the control group or a TTE simulator in the simulation group. Comprehension in both groups was then assessed using a written posttest and by performing a TTE examination on a volunteer subject. TTE examinations were graded on the ability to acquire the correct image, image quality, anatomy identification, and time required to attain proper imaging by 2 blinded experts. A second training session incorporating "hands-on" training with a volunteer subject was conducted in a subset of 21 residents (n = 11 control, n = 10 simulation). The simulation group included additional simulator training. After the second session, another posttest on a volunteer subject was administered. RESULTS: Pretest scores revealed similar preintervention knowledge among residents (56.0% ± 11.9% vs 59.3% ± 11.0%, P = 0.25; control versus simulator group, respectively). The simulation group scored higher on all criteria after the first training session: written posttest (57.9% ± 8.8% vs 68.2% ± 10.1%; P < 0.001), volunteer subject posttest image quality scores (0 to 25 scale) (6.4 ± 3.5 vs 12.4 ± 4.2; P = 0.003), anatomy identification scores (0 to 25 scale) (8.3 ± 6.6 vs 17.8 ± 6.6; P = 0.003), and percentage correct views (50 ± 19 vs 78 ± 21; P < 0.001). After the second session, all scores were again improved in the simulation group: volunteer subject posttest image quality scores (9.6 ± 3.3 vs 15.6 ± 2.8; P = 0.002), anatomy identification scores: (17.6 ± 3.8 vs 22.8 2.4; P = 0.003), and percentage correct views (80 ± 16 vs 96 ± 8; P = 0.007). DISCUSSION: This prospective randomized study demonstrated that anesthesiology residents trained with simulation acquired better skills in TTE image acquisition and anatomy identification on volunteer subjects. The educational benefit of simulation persisted even with introduction of hands-on instruction with volunteer subjects in both groups. The impact of these short-term educational approaches on longer-term retention and actual clinical application warrants further investigation.

Left ventricular endocardial and epicardial strain changes with apical myocardial ischemia in an open-chest porcine model.

Early detection of acute myocardial ischemia is critical to prevent permanent myocardial damage. The impact of apical ischemia on global left ventricular (LV) function can be difficult to characterize using traditional volume-based echocardiography measures. Myocardial strain imaging is a sensitive, quantitative marker of myocardial deformation that can measure ventricular function. Recent advances allow layer-specific measurement of endo- and epicardial strain, enhancing the ability to evaluate myocardial ischemia. This study investigates the effects of apical ischemia on LV function using epi- and endocardial strain. We hypothesize that myocardial strain will identify changes in regional and global myocardial function associated with focal apical ischemia as compared to ejection fraction (EF), and that longitudinal strain will be a better indicator of myocardial dysfunction compared to circumferential or radial strain. In a porcine model (n = 9), acute ischemia was induced by left anterior descending coronary artery occlusion. Echocardiograms were performed at baseline, during 15-min ischemia, and after reperfusion. Global longitudinal strain decreased with acute focal ischemia of the left ventricular apical region (baseline: -16.4% vs. ischemia: -12.2%; P = 0.010), with no change observed in global circumferential and radial strain or EF Both endocardial and epicardial longitudinal strain decreased by 68% (P < 0.001) in the ischemic and peri-ischemic zone, while circumferential and radial strain only decreased in endocardium of the ischemic zone. Longitudinal strain was more sensitive to ischemia, being able to detect changes in global LV function and thus may confer clinical diagnostic advantage in the evaluation of acute LV apical ischemia.