Relation of Low Serum Magnesium to Mortality and Cardiac Allograft Vasculopathy Following Heart Transplantation

Hypomagnesemia is commonly observed in heart transplant (HT) recipients receiving calcineurin inhibitors. Since low serum magnesium (s-Mg) has been implicated in the progression of atherosclerosis, potentially leading to worsening coronary heart disease, arrhythmias and sudden death, we investigated the association between s-Mg and HT outcomes. Between 2002 and 2017, 150 HT patients assessed for s-Mg were divided into high (≥1.7 mg/dL) and low s-Mg groups according to the median value of all s-Mg levels recorded during the first 3 months post-HT. Endpoints included survival, cardiac allograft vasculopathy (CAV), any-treated rejection (ATR) and NF-MACE. Kaplan-Meier analysis showed that at 15 years after HT, both survival (76 vs 33%, log-rank p = 0.007) and freedom from CAV (75 vs 48%, log-rank p = 0.01) were higher in the high versus low s-Mg group. There were no significant differences in freedom from NF-MACE or ATR. Multivariate analyses consistently demonstrated that low s-Mg was independently associated with a significant 2.6-fold increased risk of mortality and 4-fold increased risk of CAV (95%CI 1.06 to 6.4, p = 0.04; 95%CI 1.12 to 14.42, p = 0.01, respectively). In conclusion, low s-Mg is independently associated with increased mortality and CAV in HT patients. Larger multi-center prospective studies are needed to confirm these findings and to examine the effect of Mg supplementation.