Atrial arrhythmias prevalence in heart transplant patients

Abstract

The orthotopic heart transplantation (HTx), by the standard technique involves anastomosis of donor(DA) to recipient atria(RA): the composite atrium comprises two electrically distinct parts which show, generally, 2 distinct independent rhythms. Little is known about atrial arrhythmias prevalence and features in HTx patients (pts). Between January 1985 and November 2004 in Div. of Cardiac Surgery 740 pts underwent HTx by standard technique (mean age 48.1 ± 12 yrs, mean F.U. 80 mos).16/740 pts (2.2%) with incessant atrial arrhythmias underwent EPS and RF ablation. In 10/16 (62.5%) pts atrial arrhythmia originated from RA and was conducted to DA across the surgical scar: in 6, the RA arrhythmia was sustained atrial tachycardia, in 1 pt was atrial fibrillation (AF) and in 3 was pseudo premature atrial contractions (PAC)due to conduction of recipient sinus rhythm to DA. In all pts, except one, the interatrial conduction (IAC) was localized along the suture line in the right atrium, in the postero-lateral or lateral wall. In 3/16 (19%) pts the arrhythmia was a clockwise atrial flutter (AFl) with the critical isthmus between the interatrial suture line and the tricuspid valve (TV). Two/16 (12.5%) pts had focal arrhythmias; one pt had frequent PACs from the superior portion of the DA, close to the suture line; one pt had a focal tachycardia from the DA postero-lateral wall, close to the scar. One pt had an atrioventricular nodal reentry tachycardia (AVNRT) from the DA.The prevalence of sustained atrial arrhythmias in this population was 2.2%, with a prevalence of arrhythmias due to the IAC of 1.3%, AFl of 0.4%, AVNRT of 0.1% and focal atrial tachycardia of 0.4%. The sole case of AF was due to IAC. In this pts the prevalence of AF is significantly lower (1%), whereas the prevalence of AFl is significantly higher (0.09%) compared to the general population. In orthotopic HTx pts, IAC was responsible of most of atrial arrhythmias. The low prevalence of AF episodes might be explained by the electrical isolation of pulmonary and cava veins from the DA; the higher prevalence of AFl is likely due to interatrial suture line which favours macroreentry arrhythmias with critical isthmus between the interatrial suture line and the TV.