Exploring Preoperative Hypocalcemia as a Biomarker for Post Left Ventricular Assist Device Survival and Adverse Events

Abstract

<h3>Purpose</h3> Abnormal calcium handling in cardiomyocytes plays a cardinal role in the initiation and progression of heart failure. However, the effect of serum calcium levels has not been studied in chronic heart failure patients undergoing left ventricular assist device (LVAD) placement. We investigate the impact of preoperative hypocalcemia on adverse events and all-cause mortality in this population over a 24-month period post durable LVAD implantation. <h3>Methods</h3> At a single center, 177 patients received LVAD therapy between June 2011 and October 2018. Patients were classified into either hypocalcemia [(serum calcium < 8.7 mg/dL) n=40] or normocalcemia [(8.7- 10.2 mg/dL) n=108] based on preoperative levels. 29 patients were excluded due to missing data. Unadjusted and adjusted cox models were used to examine for association between hypocalcemia and 2-year all-cause mortality. Survival was compared using Kaplan-Meir plot and log-rank statistics. <h3>Results</h3> The majority of patients in both groups were undergoing LVAD placement for destination therapy (77 vs. 73%, p=0.009) and had a similar history of chronic kidney disease across groups (21 vs. 28%, p=0.36). However, there was a significantly greater number of Caucasian patients in the hypocalcemia group (85 vs. 63%, =0.004). 24-month survival was equal across groups (Log-Rank p=0.13). Likewise on Cox-modelling, there was no difference in survival seen on either the unadjusted [HR= 1.42 (0.89 - 2.27) (p=0.14)] or adjusted survival [1.39 (0.86 - 2.24) (p=0.18)] when adjusted for age, gender, INTERMACS category, and eGFR. Perioperative renal failure and need for hemodialysis were similar between groups. However, the hypocalcemia group required prolonged intubation (46 vs 28%, p=0.03), tracheostomy (28 vs 11%, p=0.001) and increased right ventricular assist device use (23 vs 8%, p=0.02). <h3>Conclusion</h3> Despite no significant impact on survival at 24-months, hypocalcemia may be a poor prognostic marker for some adverse events.