Restoring Blood Supply to the Heart While Replacing the Lungs: Is It Worth the Risk?

L transplantation (LTx) is a potentially life-saving treatment for well-selected patients with end-stage lung disease. Coronary artery disease (CAD) is a frequent comorbidity in LTx candidates with previous smoking history, which can accelerate posttransplant in patients on lifelong immunosuppressive therapy. According to the 2014 updated consensus document for the referral and listing of LTx candidates from the International Society for Heart and Lung Transplantation, untreatable cardiac dysfunction is considered an absolute contraindication for LTx unless combined heart-lung transplantation can be performed. CAD with preserved cardiac function is to be considered a relative contraindication. Patients with end-stage lung disease with mildto-moderate CAD can benefit from medical therapy, while transplant candidates with more severe CAD will need revascularization with percutaneous coronary interventions (PCI) or coronary artery bypass grafting (CABG). The degree of CAD deemed acceptable, and the timing of these coronary interventions may vary among transplant centers. In a retrospective study published in this issue of Transplantation, Halloran et al from the University of Alberta in Edmonton, Canada, examined the possible impact of CAD on survival in a cohort of 333 LTx recipients between 2004 and 2013. Outcome was compared between CAD patients undergoing concomitant CABG and LTx (7%) with those not requiring CABG (25%) and with a group without CAD (68%). Using a Cox multivariable proportion hazards regression model adjusted for age, gender, and LTx indication, CAD status itself was not identified as a risk factor associated with overall survival. However, incidence of grade 3 primary graft dysfunction was higher, and duration of mechanical ventilation, ICU, and hospital stay were longer in both CAD groups. Interestingly, unadjusted survival analysis by Kaplan-Meier and log-rank testing did reveal a significant difference between the 3 groups in median and 3-year survival, but not in hospital and 1-year survival. It is fair to state that the older recipient age (about 10 y) and the higher proportion of male gender in both CAD groups were largely responsible for the inferior overall 3-year survival compared to the nonCAD group. Likely, transplant indication negatively influenced survival since a higher proportion of patients with interstitial lung disease were transplanted in both CAD groups. These 3 recipient characteristics, adjusted for in the multivariable analysis, are well-known risk factors for survival. The authors correctly concluded that CABG at the time of LTx can be safely performed in highly selected candidates. PCI with or without stenting can be a valuable option in lung transplant candidates with proven CAD and a critical stenosis. Of note, patients with coronary stents will temporarily need dual antiplatelet therapy for a minimum of 3 to 6 months depending on the type of stent used. Continued stent patency should preferably be reassessed with coronary angiography prior to acceptance on the waiting list, particularly in case of bare metal stent which has a higher prevalence of in-stent restenosis compared to drug-eluting stents. It was interesting to notice that ±11% of their patients with CAD had PCI previously, while 2% had CABG before LTx. Another interesting discussion is the timing of intervention in patients needing both LTx and revascularization with CABG. When CABG is performed prior to listing, patients with end-stage lung disease carry a higher risk for developing pulmonary complications after sternotomy. This may result in respiratory insufficiency and death. Most centers, therefore, prefer to revascularize the heart at the time of LTx. The order of both concomitant procedures is debatable and will largely depend on the experience of the surgeons involved. Most teams prefer CABG immediately prior to LTx although Received 13 December 2018.