Impact of circadian rhythm and daytime variation on outcome after heart transplantation.

Intro: Recently, the impact of circadian rhythm and daytime variation on surgical outcomes has attracted interest. Although studies for coronary artery and aortic valve surgery report contrary results, effects on heart transplantation have not been studied.

Methods: Between 2010 and February 2022, 235 patients underwent HTx in our department. The recipients were reviewed and categorized according to the start of the HTx procedure - between 04:00 am and 11:59 am (morning, n = 79), 12:00 pm and 07:59 pm (afternoon, n = 68) or 08:00 pm and 03:59 am (night, n = 88).

Results: The incidence of high urgency status was slightly but not significantly increased (p = .08) in the morning (55.7%), compared to the afternoon (41.2%) or night (39.8%). The most important donor and recipient characteristics were comparable among the three groups. The incidence of severe primary graft dysfunction (PGD) requiring extracorporeal life support (morning: 36.7%, afternoon: 27.3%, night: 23.0%, p = .15) was also similarly distributed. In addition, there were no significant differences for kidney failure, infections, and acute graft rejection. However, the incidence of bleeding that required rethoracotomy showed an increased trend in the afternoon (morning: 29.1%, afternoon: 40.9%, night: 23.0%, p = .06). 30-day survival (morning: 88.6%, afternoon: 90.8%, night: 92.0%, p = .82) and 1-year survival (morning: 77.5%, afternoon: 76.0%, night: 84.4%, p = .41) were comparable between all groups.

Conclusion: Circadian rhythm and daytime variation did not affect the outcome after HTx. Postoperative adverse events as well as survival were comparable throughout day- and night-time. As the timing of the HTx procedure is rarely possible and depends on the timing of organ recovery, these results are encouraging, as they allow for the continuation of the prevalent practice.