Abstract 5686: Predictors of Hypocalcemia after Wide Area Circumferential Ablation of Atrial Fibrillation
Introduction: Hypocalcemia occurs frequently after wide area circumferential ablation (WACA) of atrial fibrillation and is more common with the use of open-irrigated tip ablation catheters (ITAC) than 8-mm tip ablation catheters. The mechanism of this phenomenon is unknown, but may be related to binding of calcium to myocardial proteins, volume infusion, or other factors. The present study aims to identify variables associated with acute hypocalcemia after WACA with ITAC.
Methods: We analyzed 106 patients undergoing WACA with ITAC. Pre- and post-procedural values of calcium, creatinine, glomerular filtration rate (GFR), hemoglobin, cardiac enzymes (CK, CK-MB and troponin-I), albumin, left atrial size, presence of post-procedure pericardial effusion, infused volume of normal saline, urine output, heparin, furosemide dosage, and procedure time were recorded. Univariate and multivariate analysis were performed to determine variables associated with post-ablation hypocalcemia.
Results: The population had mean age of 59±9 years, mean weight of 95±22 kilograms, and 76% were male. Mean pre-procedure GFR was 101±39 mL/min, and mean volume of normal saline infused was 5.5±1.3 liters. The means for pre-procedure calcium, post-procedure calcium, and decrease in calcium were 9.2±0.4, 7.3±0.6, and 1.9±0.7 mg/dL respectively. Of the variables measured, multivariate analysis identified pre-procedure GFR (parameter estimate −0.005) and infused volume of normal saline (parameter estimate 0.11) as factors independently associated with post-ablation hypocalcemia (p value = 0.03). Factors associated with myocardial injury were not apparently related.
Conclusions: Lower GFR and higher infused volume of normal saline correlated with acute hypocalcemia after WACA with ITAC. Rather than binding to injured myocardium, these results suggest impaired renal calcium absorption and/or dilutional effects as the principal mechanism(s).