Serum Ionized Calcium as a Prognostic Biomarker in Type B Aortic Dissection After Endovascular Treatment

Objective: Lower serum ionized calcium (iCa 2+ ) was reported to be associated with a higher risk of adverse events in patients with cardiovascular diseases. This study aimed to investigate the associations between preoperative serum iCa 2+ and outcomes of type B aortic dissection (TBAD) patients receiving thoracic endovascular aortic repair (TEVAR). Methods: Between January 2016 and December 2019, 491 TBAD patients received TEVAR in a single center. Patients with acute or subacute TBAD were included. Serum iCa 2+ (pH 7.4) was obtained from the arterial blood gas analysis before TEVAR. The study population was grouped into the hi-Ca group (1.11 mmol/L ≤ iCa 2+ < 1.35 mmol/L) and lo-Ca group (iCa 2+ < 1.11 mmol/L). The primary outcomes were all-cause mortality. The secondary outcomes were any major adverse clinical events (MACEs), which included all-cause mortality and aortic-related severe complications. To eliminate bias, 1:1 propensity score matching (PSM) was conducted. Results: Overall, 396 TBAD patients were included in this study. In the total population, there were 119 (30.1%) patients in the lo-Ca group. After PSM, 77 matched pairs were obtained for further analysis. In the matched population, the 30-day mortality and 30-day MACEs between the two groups presented significant differences (p=0.023 and 0.029, respectively). At 5 years, cumulative incidences of mortality (log-rank p<0.001) and MACEs (log-rank p=0.016) were significantly higher in the lo-Ca group than that of the hi-Ca group. Multivariate cox regression analysis indicated that lower preoperative iCa 2+ (hazard ratio for per 0.1 mmol/L decrease, 2.191; 95% confidence interval, 1.487–3.228, p<0.001) was an independent risk factor for 5-year mortality after PSM. Conclusions: Lower preoperative serum iCa 2+ might have an association with 5-year mortality in TBAD patients after TEVAR. Serum iCa 2+ monitoring in this population may facilitate the identification of critical conditions. Clinical Impact Our present study found that the cutoff value of preoperative serum iCa 2+ 1.11 mmol/L, which is slightly lower than the lower limit of the normal range of 1.15-1.35 mmol/L, worked relatively well for discerning the high-risk and low-risk TBAD patients at 5 years. Serum iCa 2+ monitoring in TBAD patients receiving TEVAR may facilitate the identification of critical conditions.