Cardiac Arrhythmias in Dogs with Mitral Regurgitation due to Myxomatous Mitral Valve Disease

Cardiac remodeling in dogs with mitral regurgitation (MR) may stimulate several supraventricular arrhythmias. The purpose of this study was to point out the potential of cardiac arrhythmias related to remodeling in dogs with MR. The study was carried out in 30 client-owned dogs with the signs of myxomatous mitral valve disease (MMVD). Routine clinical applications including cardiac examination, blood analyses and imaging procedures were performed. The inclusion criterion was the presence of left apical heart murmur. While group 1 (n:10) was defined as mild MR with regurgitant jet occupying less than 20% of the left atrial area, group 2 (n:10) was defined as moderate MR with regurgitant jet occupying between 20-40% of the left atrial area. Group 3 (n:10) was also defined as severe MR with regurgitant jet occupying more than 40% of the left atrial area. ECG variables were recorded by a 6-lead ECG machine. Arrhythmias in dogs with MMVD included Sinus Tachycardia (n:11, 37%), Sinus Arrhythmia (n:10, 33%), Supraventricular Premature Complex (n:4, 13%), Atrial Fibrillation (n:4, 13%), Tachycardia-Bradycardia Syndrome (n:2, 6%), 2nd Degree Atrioventricular Block (n:2, 6%), Left Bundle Branch Block (n:1, 3%) and Sinus Pause (n:1, 3%). No significant association were found between the presence of cardiac arrhythmias and the severity of MR groups (p>0.05). In conclusion, cardiac remodeling in dogs with MR can induce several supraventricular arrhythmias. Although we could not find significant correlations between the presence of cardiac arrhythmias and the severity of MR groups, further studies with larger case series are required