<prompt> The most common cause of tricuspid regurgitation is secondary toRheumatoid hea diseaseDilation of right ventricleCoronary aery diseaseEndocarditis due to intravenous drug abuse  <response>: Ref Harrison 19 th ed pg 1548 In at least 80 of cases, TR is secondary to marked dilation of the tricuspid annulus from RV enlargement due to PA hypeension .Functional TR may complicate RV enlargement of any cause, however, including an inferior myocardial infarction MI that involves the RV. 