Atrial fibrillation (AF) is triggered by ectopic beats originating from extensions of the left atrial myocardium over the pulmonary veins (PVs), so-called myocardial sleeves. A total of 100 hearts (393 PVs) obtained at autopsy were studied. Of these, 50 were from patients with chronic AF and 50 from controls in sinus rhythm. Out of a total of 393 PVs studied, a sleeve was present in 349 PVs (88.8%). The myocardial sleeves frequently harboured senile atrial amyloid and scarring. These two changes were evaluated semi-quantitatively (grade 0-3). Amyloidosis was found in 68% of all hearts and in 55% of all sleeves. It was more frequent in patients with AF (58.5%) than in those without (51.7%), however, without statistical significance (p values 0.948, 0.306, 0.166 and 1). Scarring was present in all 349 sleeves studied. It was significantly more severe in patients with AF (average grade 2.44) than in those without (average grade 2.00) (p values <0.001, <0.1, <0.05 and <0.01). In conclusion, amyloidosis and particularly scarring of the myocardial sleeves of the pulmonary veins, appear to be common in the elderly population as an arrhythmogenic substrate for AF.