Cardiac transplant rejection assessment with 18F-FDG PET-CT: initial single-centre experience for diagnosis and management.

BACKGROUND: Rejection is a major cause of mortality and morbidity in heart transplant (HTx) recipients. Current methods for diagnosing rejection have limitations. Imaging methods to map the entire left ventricle and reliably identify potential sites of rejection is lacking. Animal studies suggest FDG PET-CT (FDG PET) could have potential application in human HTx recipients. METHODS: Between December 2020 and February 2022, all HTx recipients at Harefield Hospital, London, with definite or suspected rejection underwent FDG PET in addition to routine work-up. RESULTS: Thirty HTx recipients (12 with definite and 18 with suspected rejection) underwent FDG PET scans. Overall, 12 of the 30 patients had FDG PET with increased myocardial avidity, of whom 2 died (17%). Eighteen patients of the 30 patients had FDG PET with no myocardial avidity and all are alive (100%, p = 0.15). All patients with definite rejection, scanned within 2 weeks of starting anti-rejection treatment, showed increased myocardial avidity. In 5 cases, FDG PET showed myocardial avidity beyond 6 weeks despite pulsed steroid treatment, suggesting unresolved myocardial rejection. CONCLUSION: Preliminary findings suggest FDG PET may have a role in diagnosing cardiac transplant rejection. Future blinded studies are needed to help further validate this.

Mini-Stern Trial: A randomized trial comparing mini-sternotomy to full median sternotomy for aortic valve replacement.

OBJECTIVE: Aortic valve replacement (AVR) can be performed either through full median sternotomy (FS) or upper mini-sternotomy (MS). The Mini-Stern trial aimed to establish whether MS leads to quicker postoperative recovery and shorter hospital stay after first-time isolated AVR. METHODS: This pragmatic, open-label, parallel randomized controlled trial (RCT) compared MS with FS for first-time isolated AVR in 2 United Kingdom National Health Service hospitals. Primary endpoints were duration of postoperative hospital stay and the time to fitness for discharge from hospital after AVR, analyzed in the intent-to-treat population. RESULTS: In this RCT, 222 patients were recruited and randomized (n = 118 in the MS group; n = 104 in the FS group). Compared with the FS group, the MS group had a longer hospital length of stay (mean, 9.5 days vs 8.6 days) and took longer to achieve fitness for discharge home (mean, 8.5 days vs 7.5 days). Adjusting for valve type, sex, and surgeon, hazard ratios (HRs) from Cox models did not show a statistically significant effect of MS (relative to FS) on either hospital stay (HR, 0.874; 95% confidence interval [CI], 0.668-1.143; P = .3246) or time to fitness for discharge (HR, 0.907; 95% CI, 0.688-1.197; P value = .4914). During a mean follow-up of 760 days (745 days for the MS group and 777 days for the FS group), 12 patients (10%) in the MS group and 7 patients (7%) in the FS group died (HR, 1.871; 95% CI, 0.723-4.844; P = .1966). Average extra cost for MS was £1714 during the first 12 months after AVR. CONCLUSIONS: Compared with FS for AVR, MS did not result in shorter hospital stay, faster recovery, or improved survival and was not cost-effective. The MS approach is not superior to FS for performing AVR.

Functional assessment and transplantation of the donor heart after circulatory death.

BACKGROUND: After a severe shortage of brain-dead donors, the demand for heart transplantation has never been greater. In an attempt to increase organ supply, abdominal and lung transplant programs have turned to the donation after circulatory-determined death (DCD) donor. However, because heart function cannot be assessed after circulatory death, DCD heart transplantation was deemed high risk and never adopted routinely. We report a novel method of functional assessment of the DCD heart resulting in a successful clinical program. METHODS: Normothermic regional perfusion (NRP) was used to restore function to the arrested DCD heart within the donor after exclusion of the cerebral circulation. After weaning from support, DCD hearts underwent functional assessment with cardiac-output studies, echocardiography, and pressure-volume loops. In the feasibility phase, hearts were transported perfused before evaluation of function in modified working mode extracorporeally. After the establishment of a reliable assessment technique, hearts with demonstrable good function were then selected for clinical transplantation. RESULTS: NRP was instituted in 13 adult DCD donors, median age of 33 years (interquartile range [IQR], 28-38 years), after a median ischemic time from withdrawal to perfusion of 24 minutes (IQR, 21-29; range, 17-146 minutes). Two of 4 hearts in the feasibility phase were unsuitable for transplantation after functional assessment. Nine DCD hearts were transplanted in the clinical phase, with 100% survival. The median intensive care duration was 5 days (IQR, 4-5 days), with 2 patients requiring mechanical support. There were no episodes of rejection (total, 1,436 patient-days; range, 48-297). During the same period, we performed 20 standard heart transplants using brain-dead donors. CONCLUSIONS: NRP allows rapid reperfusion and functional assessment of the DCD donor heart, ensuring only viable hearts are selected for transplantation. This technique minimizes the risk of primary graft dysfunction and maximizes confidence in DCD heart transplantation, realizing a 45% increase in our heart transplant activity.

Right ventricular reverse remodeling after pulmonary endarterectomy: magnetic resonance imaging and clinical and right heart catheterization assessment.

The objective of this study was to assess the effect of pulmonary endarterectomy (PEA) on right ventricular (RV) reverse remodeling using magnetic resonance imaging (MRI) and to correlate MRI findings with clinical and hemodynamic outcomes postsurgery. We performed a retrospective analysis in 72 patients undergoing PEA surgery in whom MRI and right heart catheterization (RHC) were performed preoperation and 3 months postoperation. RV volumes and mass were assessed by MRI. Continuous variables were expressed as means, changes were compared with a paired t test, and associations between the variables were explored using Pearson correlation coefficients. The mean age was 57 years, and 51% were male. Both RV end-diastolic volume (EDV; 176-117 mL; P < 0.001) and RV end-systolic volume (ESV; 129-64 mL; P < 0.001) reduced significantly following PEA. Preoperative pulmonary artery pressure (PAP) correlated moderately with ESV (r = 0.46, P < 0.001). Postoperatively, PAP correlated with EDV (r = 0.45, P < 0.001) and ESV (r = 0.44, P < 0.001). Moderate correlation was present between hemodynamic parameters: PAP, pulmonary vascular resistance, and right atrial pressure with pre- and postoperation end-systolic and end-diastolic RV mass (P < 0.001). RHC and MRI measurements of cardiac output and RV volumes were significantly different (P < 0.001). In conclusion, RV reverse remodeling, as measured by improvement in RV volumes and mass by MRI, was observed for 3 months in patients who underwent PEA surgery. This is the largest series of patients with pre- and post-PEA MRI assessment so far reported. MRI detects changes in parameters reflecting cardiac remodeling and pulmonary clearance, but measurements are significantly different from those of RHC.

Swan-Ganz catheter assessment of donor hearts: outcome of organs with borderline hemodynamics.

BACKGROUND: High-dosage inotrope use or periods of hypotension may cause rejection of donor hearts for transplantation. At our institution, we do not refuse potential donor organs based on these criteria alone before Swan-Ganz catheter (SGC) assessment. In this study, we evaluate the role of the SGC in donor heart resuscitation and selection and assess the outcome of using borderline organs. METHODS: We retrospectively analyzed 129 donors assessed between 1996 and 1999, all with complete hemodynamic data. Two sets of SGC measurements were analyzed: one set from the initial assessments, and one set from assessments made just before organ harvesting. The physiologic targets were mean blood pressure >60 mm Hg, central venous pressure <12 mm Hg, pulmonary capillary wedge pressure <12 mm Hg, left ventricular stroke work index >15 x g.m/m(2), and use of only one inotrope. A poorly functioning heart was defined as an organ failing on 2 or more of these criteria. Hemodynamic categories were defined as A, good function throughout assessment; B, sub-optimal function and then improvement; and C, decreasing or poor function throughout. We have a policy to avoid allocating sub-optimal organs to high-risk recipients. RESULTS: One hundred fourteen donor hearts went on to be transplanted: 75 as orthotopic hearts and 39 as heart-lungs (5 of these were heart, lung, and liver transplantations, not reported further here). Of the 75 donor hearts used for heart transplantations, 53 were from Category A, 9 were from Category B, and 13 were from Category C. Of the donor hearts used for the 34 heart-lung transplantations 16 were from Category A, 10 were from Category B, and 8 were from Category C. Three patients died of donor organ failure: 1 of the corresponding hearts was from Category B, and 2 were from Category C. When comparing separately the outcome of the 2 procedures, we found no significant difference in duration of stay in the intensive care unit, requirement for mechanical support, 30-day mortality, or 1-year survival among patients with hearts from Categories A, B, and C. Ischemic time was the only significant risk factor for death (p = 0.006). CONCLUSIONS: Use of organs from Categories B and C permitted expansion of the donor pool without compromising short-term outcome. However, these organs should be used with caution in combination with other risk factors, in particular long ischemic time.