Tricuspid Annular Remodeling in Tachycardia Induced Cardiomyopathy With Functional Tricuspid Regurgitation

This novel study examined tricuspid annular (TA) remodeling in conscious, awake sheep with functional tricuspid regurgitation (FTR) using tachycardia-induced cardiomyopathy. Fifteen sheep underwent thoracotomy with sonomicrometry crystal implantation around the TA and right ventricular epicardium. Eight surviving animals had baseline measurements acquired while awake, then underwent pacing (180-240 bpm for 18±2 days) until developing FTR. The model produced moderate-severe FTR, with a 48 percent increase in right ventricular (RV) volume, a 57 percent enlargement of the TA area, and a 24 percent perimeter expansion. Critically, all annular segments dilated significantly: the anterior perimeter increased by 27 percent, the posterior perimeter increased by 17 percent, and the septal perimeter by 25 percent (all p<0.01), with the TA area contraction decreasing from 16.6 percent to 4.5 percent. The authors conclude that septal annular dilation, which has traditionally been unsupported by partial rings, may explain high annuloplasty failure rates, suggesting that complete annular support could improve surgical durability in severe FTR.