Background: In Europe, there is greater acceptance of hearts from higher-risk donors for transplantation, whereas in North America, the donor heart discard rate is significantly higher. A Donor Utilization Score (DUS) was used to compare European and North American donor characteristics for recipients included in the International Society for Heart and Lung Transplantation registry from 2000 to 2018. DUS was further evaluated as an independent predictor for 1-year freedom from graft failure, after adjusting for recipient risk. Lastly, we assessed donor-recipient risk matching with the outcome of 1-year graft failure. Methods: DUS was applied to the International Society for Heart and Lung Transplantation cohort using meta-modeling. Posttransplant freedom from graft failure was summarized by Kaplan-Meier survival. Multivariable Cox proportional hazard regression was applied to quantify the effects of DUS and Index for Mortality Prediction After Cardiac Transplantation score on the 1-year risk of graft failure. We present 4 donor/recipient risk groups using the Kaplan-Meier method. Results: European centers accept significantly higher-risk donor hearts compared to North America. DUS 0.45 versus 0.54, P <0.005). DUS was an independent predictor for graft failure with an inverse linear relationship when adjusted for covariates ( P <0.001). The Index for Mortality Prediction After Cardiac Transplantation score, a validated tool to assess recipient risk, was also independently associated with 1-year graft failure ( P <0.001). In North America, 1-year graft failure was significantly associated with donor-recipient risk matching (log-rank P <0.001). One-year graft failure was highest with pairing of high-risk recipients and donors (13.1% [95% CI, 10.7%–13.9%]) and lowest among low-risk recipients and donors (7.4% [95% CI, 6.8%–8.0%]). Matching of low-risk recipients with high-risk donors was associated with significantly less graft failure (9.0% [95% CI, 8.3%–9.7%]) than high-risk recipients with low-risk donors (11.4% [95% CI, 10.7%–12.2%]) Conclusions: European heart transplantation centers are more likely to accept higher-risk donor hearts than North American centers. Acceptance of borderline-quality donor hearts for lower-risk recipients could improve donor heart utilization without compromising recipient survival.

Background: Cardiogenic shock (CS) is a significant complication of Takotsubo syndrome (TTS), contributing to heightened mortality and morbidity. Despite this, the Society for Cardiovascular Angiography and Interventions (SCAI) staging system for CS severity lacks validation in patients with TTS and CS. This study aimed to characterize a patient cohort with TTS using the SCAI staging system and assess its utility in cases of TTS complicated by CS. Methods and Results: From a TTS national registry, 1591 consecutive patients were initially enrolled and stratified into 5 SCAI stages (A through E). Primary outcome was all‐cause in‐hospital mortality; secondary end points were TTS‐related in‐hospital complications and 1‐year all‐cause mortality. After exclusions, the final cohort comprised 1163 patients, mean age 71.0±11.8 years, and 87% were female. Patients were categorized across SCAI shock stages as follows: A 72.1%, B 12.2%, C 11.2%, D 2.7%, and E 1.8%. Significant variations in baseline demographics, comorbidities, clinical presentations, and in‐hospital courses were observed across SCAI shock stages. After multivariable adjustment, each higher SCAI shock stage showed a significant association with increased in‐hospital mortality (adjusted odds ratio: 1.77–29.31) compared with SCAI shock stage A. Higher SCAI shock stages were also associated with increased 1‐year mortality. Conclusions: In a large multicenter patient cohort with TTS, the functional SCAI shock stage classification effectively stratified mortality risk, revealing a continuum of escalating shock severity with higher stages correlating with increased in‐hospital mortality. This study highlights the applicability and prognostic value of the SCAI staging system in TTS‐related CS.

Background: The real impact of the degree of association (DoA) between endpoint components of a composite endpoint (CE) on sample size requirement (SSR) has not been explored. We estimate the impact of the DoA between death and acute myocardial infarction (AMI) on SSR of trials using use the CE of major adverse cardiac events (MACE). Methods: A systematic review and quantitative synthesis of trials that include MACE as the primary outcome through search strategies in MEDLINE and EMBASE electronic databases. We limited to articles published in journals indexed in the first quartile of the Cardiac & Cardiovascular Systems category (Journal Citation Reports, 2015–2020). The authors were contacted to estimate the DoA between death and AMI using joint probability and correlation. We analyzed the SSR variation using the DoA estimated from RCTs. Results: Sixty-three of 134 publications that reported event rates and the therapy effect in all component endpoints were included in the quantitative synthesis. The most frequent combination was death, AMI, and revascularization (n = 20; 31.8%). The correlation between death and AMI, estimated from 5 trials¸ oscillated between − 0.02 and 0.31. SSR varied from 14,602 in the scenario with the strongest correlation to 12,259 in the scenario with the weakest correlation; the relative impact was 16%. Conclusions: The DoA between death and AMI is highly variable and may lead to a considerable SSR variation in a trial including MACE.