Right ventricular undersizing is associated with increased 1-year mortality

Right ventricular sizing and pulmonary vascular resistance: How much mass do you need?

OBJECTIVE

Right ventricular (RV) donor-recipient sizing has been demonstrated to be a sensitive predictor for mortality after heart transplantation. We sought to understand the relationship between donor-recipient RV mass (RVM) ratio and pulmonary vascular resistance (PVR) on outcomes after heart transplantation.

METHODS

Adult heart transplant recipients from the United Network for Organ Sharing database were included (N = 42,594). The influence of RVM ratio and PVR on 1-year mortality was assessed by logistic regression after multivariable adjustment.

RESULTS

Among transplant recipients, median PVR was 2.4 Wood units (WU) (range, 1.7-3.3 WU) and median RVM ratio was 1.2 (1.0-1.3). Without considering PVR, RVM ratio was highly associated with postoperative dialysis (odds ratio [OR], 0.49; P < .001) and 1-year mortality (OR, 0.64; P < .001). Without considering RVM ratio, PVR was highly associated with 1-year mortality (OR, 1.05; P < .001), but not postoperative dialysis (OR, 0.98; P = .156). When considering both RVM ratio and PVR, the risk associated with each remained significant, but PVR did not modify the effect of RVM ratio on 1-year mortality (RVM ratio × PVR: OR, 0.99; P = .858). To maintain a consistent predicted 1-year mortality, RVM ratio would need to increase by 0.12 for each WU increase in PVR. Secondary analyses found that a 1 WU change in PVR was associated with an 11% increase in mortality risk in RVM ratio mismatched patients (RVM ratio < 1; P = .001), but only a 5% increase in RVM ratio matched patients (RVM ratio ≥ 1; P = .003).

CONCLUSIONS

RVM ratio and recipient PVR are independent predictors of 1-year mortality. Still, a larger RV mass may be utilized to mediate the effects of an elevated PVR.

Right Ventricular Mass Oversizing Is Associated With Improved Post-transplant Survival in Heart Transplant Recipients With Elevated Transpulmonary Gradient

BACKGROUND

This study evaluates the effects of pre-transplant transpulmonary gradient (TPG) and donor right ventricular mass (RVM) on outcomes following heart transplantation.

METHODS

UNOS registry was queried to analyze adult recipients who underwent primary isolated heart transplantation from 1/1/2010 to 12/31/2018. The recipients were dichotomized into 2 groups based on their TPG at the time of transplantation, < 12 and ≥ 12 mmHg. The outcomes included 5-year survival and post-transplant complications. Propensity score-matching was performed. Subanalysis was performed to evaluate the effects of donor-recipient RVM matching, where a ratio < 0.85 was classified as undersized, 0.85-1.15 as size-matched, and > 1.15 as oversized.

RESULTS

We analyzed 17,898 isolated heart transplant recipients, and 5129 (28.7%) recipients had TPG ≥ 12 mmHg at the time of transplantation. The recipients with TPG ≥ 12 mmHg experienced significantly lower 5-year survival rates (78.4% vs 81.2%; P < 0.001) compared to the recipients with TPG < 12 mmHg, and this finding persisted in the propensity score-matched comparison. The recipients with TPG ≥ 12 mmHg experienced a higher rate of post-transplant dialysis and a longer duration of hospitalization. Oversizing the donor RVM considerably improved the 5-year survival among the recipients with TPG ≥ 12 mmHg, comparable to those with TPG < 12 mmHg.

CONCLUSION

Elevated pre-transplant TPG is associated with significantly reduced post-transplant survival. However, oversizing the donor RVM is associated with improved survival rates in recipients with elevated TPG, resulting in improved survival that is comparable to that of recipients with normal TPG. Therefore, careful risk stratification and donor matching among recipients with elevated TPG is essential to improve outcomes in this vulnerable population.

Speckle-Tracking Echocardiography in Right Ventricular Function of Clinically Well Patients with Heart Transplantation

Heart transplantation (HT) is the mainstream therapy for end-stage heart disease. However, the cardiac graft function can be affected by several factors. It is important to monitor HT patients for signs of graft dysfunction. Transthoracic echocardiography is a simple, first-line, and non-invasive method for the assessment of cardiac function. The emerging speckle-tracking echocardiography (STE) could quickly and easily provide additive information over traditional echocardiography. STE longitudinal deformation parameters are markers of early impairment of ventricular function. Although once called the "forgotten ventricle", right ventricular (RV) assessment has gained attention in recent years. This review highlights the potentially favorable role of STE in assessing RV systolic function in clinically well HT patients.

The Use of Impella 5.5 for Donor-Heart Hemodynamic Support in Heart Transplantation

Primary graft dysfunction is a feared complication and cause of mortality post-heart transplant. Primary graft dysfunction may require mechanical circulatory support, such as venoarterial extracorporeal membrane oxygenation, which carries its own risk for complications. We developed a new mechanical circulatory support method for patients who underwent heart transplant bridged with Impella 5.5, which was then placed into the donor heart. Among 12 heart transplants, four required Impella 5.5 support. The average age was 55.8 years. The mean duration for postoperative mechanical circulatory support was 3.8 days, ranging from 2 to 5 days. No patients developed severe right ventricular dysfunction. In our limited study, complications and mortality associated with the replanted Impella 5.5 were both 0%.

Donor/recipient ascending aortic diameter ratio as a novel potential metric for donor selection and improved clinical outcomes in heart transplantation: a propensity score-matched study

Background

Donor/recipient size matching is paramount in heart transplantation. Body weight, height, body mass index, body surface area, and predicted heart mass (PHM) ratios are generally used in size matching. Precise size matching is important to achieve better clinical outcomes. This study aims to determine the donor/recipient ascending aortic diameter (AAoD) ratio as a metric for donor selection and its effect on postoperative clinical outcomes in heart transplant patients.

Methods

We retrospectively reviewed all consecutive patients who underwent heart transplantation from January 2015 to December 2018. A cutoff value of 0.8032 for the donor/recipient AAoD ratio (independent variable for the primary endpoint during unmatched cohort analysis) was determined for predicting in-hospital mortality. The patients were divided into two groups based on the cutoff value. Group A, AAoD < 0.8032 (n = 96), and Group B, AAoD > 0.8032 (n = 265). A propensity score-matched (PSM) study was performed to equalize the two groups comprising 77 patients each in terms of risk. A Cox regression model was developed to identify the independent preoperative variables affecting the primary end-point. The primary endpoint was all-cause in-hospital mortality.

Results

A total of 361 patients underwent heart transplantation during the given period. On the multivariate analysis, donor/recipient PHM ratio [HR 16.907, 95% confidence interval (CI) 1.535-186.246, P = 0.021], donor/recipient AAoD ratio < 0.8032 (HR 5.398, 95% CI 1.181-24.681, P = 0.030), and diabetes (HR 3.138, 95% CI 1.017-9.689, P = 0.047) were found to be independent predictors of in-hospital mortality. Group A had higher 3-year mortality than Group B (P = 0.022). The surgery time was longer and postoperative RBC, plasma, and platelets transfusion were higher in Group A (P < 0.05). Although not statistically significant the use of continuous renal replacement therapy (P = 0.054), and extracorporeal membrane oxygenation (P = 0.086), was realatively higher, and ventilation time (P = 0.079) was relatively longer in Group A.

Conclusions

The donor/recipient AAoD ratio is a potential metric for patient matching and postoperative outcomes in heart transplantation. A donor/recipient AAoD ratio > 0.8032 could improve post-heart transplantation outcomes and donor heart utilization.

Total ventricular mass oversizing +50% or greater was a predictor of worse 1-year survival after heart transplantation

OBJECTIVES

Current donor-recipient size matching guidelines rely primarily on body weight, with no specified oversizing cutoff values. Recent literature has explored predicted total ventricular mass matching over body weight matching. We aim to explore the impact of total ventricular mass oversizing on heart transplant outcomes.

METHODS

The United Network for Organ Sharing database was queried for adults who underwent primary heart transplant from 1997 to 2017. By using validated equations, donor-recipient total ventricular mass mismatch was calculated. Donor-recipient pairs were divided into 3 groups by total ventricular mass mismatch. Post-heart transplant 1-year survival was analyzed using the Kaplan-Meier method and Cox proportional hazards models. We also investigated post-heart transplant complications, independent predictors for mortality, donor-recipient sex mismatch, and donor-recipient body habitus in total ventricular mass mismatch greater than +50%.

RESULTS

A total of 34,455 donor-recipient pairs were included. Fractional polynomial regression demonstrated increased the risk of mortality with higher total ventricular mass mismatch. Total ventricular mass mismatch of +48.3% maximized the Youden Index. Donor-recipient pairs were subsequently grouped by total ventricular mass mismatch as -20% to +30%, +30% to +50%, and greater than +50%. Total ventricular mass mismatch greater than +50% was an independent risk factor for 1-year mortality (hazard ratio, 1.40, P = .004) and was associated with increased postoperative stroke (P = .002). Some 80.3% of these recipients were smaller female patients with male donors. Total ventricular mass mismatch from +30% to +50% was not associated with worse survival (P = .17).

CONCLUSIONS

Total ventricular mass mismatch greater than +50% is associated with worse 1-year survival, although this group comprises a small portion of heart transplant. total ventricular mass mismatch from +30% to +50% is not associated with worse survival. These outcomes should be considered in selecting donors and in efforts to expand the potential donor pool.

Short stature is a risk factor for heart transplant morbidity and mortality

BACKGROUND

Short stature is associated with mortality after cardiac surgery and may increase size mismatch risk among transplant recipients. Yet, stature's impact on heart transplant outcomes is not well-characterized.

METHODS

The Scientific Registry of Transplant Recipients was queried for data on all adult heart transplants in the United States from 2000 to 2022. Recipients were stratified into five cohorts by sex-corrected stature. Morbidity was assessed with Kruskal-Wallis and chi-squared tests. Mortality was analyzed using Kaplan-Meier estimation. Risk factors for mortality were assessed with multivariable Cox regression.

RESULTS

Among 43,420 transplant recipients, 5321 (12.2%) had short stature (females >4'11″ & ≤5'1″; males >5'4″ & ≤5'7″) and 765 (1.8%) had very short stature (females ≤4'11″; males ≤5'4″). Very short stature patients had higher waitlist status (1A and 1), more congenital heart disease, and received more oversized donor hearts than other cohorts (all p < 0.05). Very short stature patients had decreased 30-day, 1-, 5-, and 10-year survival (94.6%, 84.3%, 69.3% and 52.5%, respectively, all p < 0.001), but less acute rejection (p = 0.005) and comparable stroke rates (p = 0.107). On multivariable regression adjusting for congenital heart disease and oversized donor hearts, very short and short stature were associated with 10-year mortality (hazard ratios: 1.40 and 1.12, respectively, both p < 0.005).

CONCLUSIONS

Short stature confers increased mortality risk for heart transplant recipients and merits inclusion in prognostic models.

Choosing wisely: incorporating appropriate donor-recipient size matching in heart transplantation

Historically, transplantation of a female donor heart to male recipient has been viewed with caution given evidence of suboptimal outcomes, particularly in special populations such as patients with pulmonary hypertension or those supported by ventricular assist devices. However, the use of predicted heart mass ratio for donor-recipient size matching demonstrated that the size of the organ rather than sex of the donor was most responsible for the outcomes. With the advent of the predicted heart mass ratio, avoiding female donor hearts for male recipients is no longer justified and may result in unnecessary waste of available organs. In this review, we highlight the value of donor-recipient sizing by predicted heart mass ratio and summarize the evidence of different approaches to the donor-to-recipient size and sex matching. We conclude that the utilization of predicted heart mass is currently considered a preferred method of matching heart donors and recipients.

Donor Utilization in the Recent Era: Effect of Sex, Drugs, and Increased Risk

Background:

Heart transplantation volumes have increased in recent years, yet less than a third of donors are typically accepted for transplantation. Whether donor sex, donor drug use, or perception of increased risk affects utilization for transplantation is unclear.

Methods:

The United Network for Organ Sharing database was queried for donors from January 1, 2007, to December 31, 2017. Donor toxicology was collected when available. Multivariate analysis was conducted to examine correlations with donor utilization.

Results:

Between January 1, 2007, and December 31, 2017, there were 87 816 heart donors aged ≥15 years. The mean age was 42.7±15.8 years, and 24 831 donors (28.3%) were utilized for heart transplantation. Subsequent analyses focused on donors between 15 and 39 years old.

The strongest associations with donor acceptance were for male donor sex, blood type, hepatitis C antibody, donor age, left ventricular hypertrophy, and history of donor drug use. After removing hepatitis C, Public Health Service Increased Risk was identified as a strong negative predictor. Most positive drug toxicology results were associated with donor nonuse except for donors between 15 and 19 years of age. Exceptions included alcohol, marijuana, and cocaine. Opiates were associated with less utilization at all donor ages. The Public Health Service Increased Risk status was associated with significantly less utilization in all age groups except 15- to 19-year-old donors.

Conclusions:

While male donors were preferentially utilized, donors with drug use or those deemed Public Health Service Increased Risk were significantly less utilized for heart transplantation. Further consideration of such donors would be appropriate particularly as the demand for transplantation continues to increase.