Importance of the cardiothoracic ratio in the evaluation of cardiac transplant candidates

Utility of Recipient Cardiothoracic Ratio in Predicting Delayed Chest Closure after Heart Transplantation

BACKGROUND

 Predicted cardiac mass (PCM) has been well validated for size matching donor hearts to heart transplantation recipients. We hypothesized that cardiothoracic ratio (CTR) could be reflective of recipient-specific limits of oversizing, and sought to determine the utility of donor to recipient PCM ratio (PCMR) and CTR in predicting delayed chest closure after heart transplantation.

METHODS

 A retrospective review of prospectively collected data on 38 consecutive heart transplantations performed at our institution from 2017 to 2020 was performed. Donor and recipient PCM were estimated using Multi-Ethnic Study of Atherosclerosis predictive models. Receiver operating characteristic analysis was performed to determine the discriminatory power of the ratio of PCMR to CTR in predicting delayed sternal closure.

RESULTS

 Of the 38 patients, 71.1% (27/38) were male and the median age at transplantation was 58 (interquartile range [IQR]: 47-62) years. Ischemic cardiomyopathy was present in 31.6% of recipients (12/38). Median recipient CTR was 0.63 [IQR: 0.59-0.66]. Median donor to recipient PCMR was 1.07 [IQR: 0.96-1.19], which indicated 7% oversizing. Thirteen out of 38 (34.2%) underwent delayed sternal closure. Primary graft dysfunction occurred in 15.8% (6/38). PCMR/CTR showed good discriminatory power in predicting delayed sternal closure [area under the curve: 80.4% (65.3-95.6%)]. PCMR/CTR cut-off of 1.7 offered the best trade-off between the sensitivity (69.6%) and specificity (91.7%).

CONCLUSION

 CTR could be helpful in guiding the recipient-specific extent of oversizing donor hearts. Maintaining the ratio of PCMR to CTR below 1.7 could avoid excessive oversizing of the donor heart.

Assessing donor-recipient size metrics for heart transplant outcomes: UNOS database analysis

STUDY

There is no widely accepted donor to recipient size-match metric to predict outcomes in cardiac transplant. The predictive ability of size-match metrics has not been studied when recipients are stratified by heart failure etiology. We sought to assess the performance of commonly used size metrics to predict survival after heart transplant, accounting for restrictive vs. non-restrictive pathology.

METHODS

The UNOS registry was queried from 2000-2017 for all primary isolated heart transplants. Donor-recipient ratios were calculated for commonly used size metrics and their association with survival was assessed using continuous, nonlinear analysis.

RESULTS

29,817 patients were identified. Height (p<0.001), predicted heart mass (PHM) (p = 0.003), ideal body weight (IBW) (p<0.001) and body mass index (BMI) (p = 0.003) ratios were significantly associated with survival, while weight and body surface area (BSA) ratios were not. When stratified, only BMI ratio retained significance for both restrictive (p = 0.051) and non-restrictive (p = 0.003) subsets. Recipients with restrictive etiology had increased risk of mortality with both a lower and higher BMI ratio.

CONCLUSIONS

While many metrics show association with survival in the non-restrictive subset, BMI is the only metric that retains significance in the restrictive subset. Recipients with restrictive and non-restrictive etiologies of heart failure tolerate size mismatch differently. This article is protected by copyright. All rights reserved.