Coronary Artery Bypass Surgery for Patients Presenting with Ventricular Arrhythmias: Propensity Matched Early and Late Outcome

Objectives: Patients with ischemic ventricular arrhythmia (IVA) in the form of fibrillation or tachycardia represent a surgical challenge. Evidence in the literature suggests that ventricular arrhythmia threatens survival even after cardiac surgery. We aim to review the results of our patients presenting with IVA with regard to short and long term outcome following cardiac surgery. Methods: This was a retrospective study of data entered prospectively into our cardiac surgical database between January 1999 and September 2015. A total of 9609 patients underwent Cardiac Surgery which included 54 patients after surviving IVA. The short- and long-term outcomes were compared to a propensity matched group. Actuarial survival was calculated using Kaplan Meier analysis. Results: The 54 study group patients were propensity matched on a 1:2 basis with a control group of non-IVA (n = 108). The baseline preoperative characteristics and risk factors were similar between the 2 groups and all cases underwent CABG only. Univariate analysis showed pacing postoperatively (33.3 vs 66.7%;p = 0.001) and postoperative ventricular arrhythmia (10 vs 22.2%;p = 0.039) to be significantly higher in the IVA group. Cox-multivariate analysis showed postoperative ventricular arrhythmia in either group (Hazard ratio = 1.5) to be the only significant factor to impact mortality (p 0.001). Long term survival was not significantly different between the two groups (10.4;CI: 9.08 - 11.75 vs 9.3;CI: 7.61 - 11.01 yrs, p = 0.3). Conclusion: Cardiac surgery on patients presenting with IVA can be performed safely yielding short and long term results equivalent to non-IVA cases. These patients should not be denied surgery with consideration of good long term outcome.

<i>In Vitro</i>Characterisation of Pharmacological Effect of Prostacyclin Analogues in Comparison to Phosphodiesterase Inhibitors on Small Human Pulmonary Vessels

Background and Aim of Study: The phosphodiesterase inhibitors (Sildenafil and Milrinone), Nitric Oxide donor Sodium Nitroprusside (SNP) and prostacyclin analogs are commonly used pulmonary vasodilators to treat pulmonary hypertension. In the past few years, we have used human pulmonary artery rings in vitro to evaluate pulmonary vascular resistance. The main objective of the current study is to document the pharmacological impact of clinically used prostacyclin analogs on the human pulmonary system in parallel with phosphodiesterase inhibitors and SNP. Methods: The study used human pulmonary artery rings of internal diameter of 2 - 4 mm and length of 2 mm. These were extracted from patients with lung resections. These rings were then mounted on a multiwire myograph, and changes in isometric tension were noted. Then, concentration response curves were constructed to Sildenafil (Sd), Milrinone (Mil), Sodium Nitroprusside (SNP), Epoprostenol (Ep), Iloprost (Ip) and Treprostinil (Tp). Results: 52 pulmonary artery rings were used in these experiments. Sildenafil, Milrinone, SNP, Epoprostenol, Iloprost and Treprostinil caused a concentration-dependent vasodilation in small human pulmonary arteries (pEC50: 5.97 ± 0.22, 5.99 ± 0.12, 7.64 ± 0.08, 7.53 ± 0.14, 8.84 ± 0.15 and 9.48 ± 0.13 respectively, n = 8 to 12). The efficacy for the same was in the order: Tp = Ip > Ep > Mil > SNP > Sd. The potency varied in the order: Tp > Ip > SNP > Ep > Mil > Sd. Conclusion: This research showed the efficacy as well as the potency of SNP and phosphodiesterase inhibitors and prostacyclin analogs on the human pulmonary vasculature. Treprostinil and Iloprost exhibited maximum relaxation. However, Sildenafil and SNP showed lesser impact. These effects need to be considered for clinical studies for enhanced patient outcomes.