Expression of Leu-7 in myocardial sleeves around human pulmonary veins

Background: Atrial fibrillation (AF) is the most common sustained clinical arrhythmia. Myocardial sleeves onto pulmonary veins (PVs) have been recognized as a frequent site of origin of focal triggers for this arrhythmia. Expression of Leu-7 has been hypothesized to correspond with abnormal atrial automaticity. Objective: To evaluate a possible role of the Leu-7 immunoreactivity in AF patients, we studied Leu-7 expression in myocardial sleeves. Methods: Leu-7 was studied immunohistochemically in paraffin-embedded specimens from 55 human autopsied hearts (mean age 69 years, range 42–94 years, 34 males, 21 females). Twenty-two of the subjects had previous history of AF. Results: Myocardial sleeves were found in 151 out of a total number of 220 PVs (68.6%). Leu-7 granular cytoplasmatic positivity was observed in 15 (9.9%) PVs from 12 different hearts: 6 (15.4%) in the right superior, 4 (10.2%) in the right inferior, 4 (10.8%) in the left superior and 1 (2.7%) in the left inferior PV. This finding was revealed both in patients with and without the history of AF. Conclusions: Leu-7 positivity, hypothesized to correspond with abnormal atrial automaticity, can be detected in some myocardial sleeves around PVs. However, no statistical relationship to previous history of AF was found.