Abstract 11969: Post Myocardial Infarction Hearts Exhibit Larger Calcium Sparks which are Not Modified by Flecainide

A proportion of arrhythmias which occur following MI and ischemic cardiomyopathy may result from increased sarcoplasmic reticulum (SR) Ca2+ leak. In the CAST trial flecainide was assessed for its ability to reduce post-MI arrhythmias but in fact increased arrhythmias and mortality. Recent evidence has shown flecainide to be effective in the therapy of some forms of triggered arrhythmia, in part through reduction in Ca2+ spark amplitude. We set out to assess whether flecainide had a specific effect on post MI cardiomyocytes that might help explain the lack of benefit seen in CAST. Confocal microscopy of isolated intact rat ventricular cardiomyocytes treated with 30nM isoprenaline (ISO) was used to assess sparks in the presence (FLEC) or absence (CTRL) of 5µM flecainide loaded for 5 mins (n=733 sparks from 52 cells). Cells were isolated either from rats with MI induced approximately 4-8 weeks earlier (MI) or age matched controls (AMC). This gave four main conditions for spark measurement - AMC-CTRL, AMC-FLE...