Abstract
This thesis considers the role of Vitamin C genes on cardiac conduction. Firstly we performed a systematic literature review to ascertain the protective effects of Vitamin C dosing in preventing in-hospital onset atrial fibrillation post cardiac surgery. We noted considerable heterogeneity across published studies on Vitamin C dosing and AF outcomes in cardiac surgery. We wondered if this heterogeneity may be due to genetic polymorphisms in the Vitamin C transporter, responsible for Vitamin C uptake into cardiac tissues. There are no studies that we are aware of that have explored Vitamin C transporter polymorphisms and cardiac conduction.
It is known that 6 week dosing of Vitamin C reportedly decreases electrocardiogram (ECG) QRS duration in young healthy volunteers. Our aims were to explore genetic polymorphisms in the Vitamin C transporter on cardiac ventricular conduction. We used a retrospective rural bio-bank where ECG derived QRS duration was available. Specifically we determined Vitamin C transporter rs1776964 genotyping using DNA (derived from blood samples) from 274 Australian rural subjects (with and without type 2 diabetes mellitus) aged 21 years and over. We demonstrated that the ECG QRS duration had no significant association across rs1776964 genotypes.
In conclusion further Vitamin C transporter genotype studies may be required to understand associations between Vitamin C dosing and QRS duration. Vitamin C transporter polymorphisms may explain the heterogeneity in atrial fibrillation outcomes in post cardiac surgery, although we cannot demonstrate an association in our study with ventricular conduction.