Impaired myocardial perfusion and perfusion reserve associated with increased coronary resistance in persistent idiopathic atrial fibrillation.

AIMS: Patients with atrial fibrillation (AF) present with symptoms of myocardial ischaemia despite exclusion of coronary artery disease. A small vessel disease has been suggested. We quantified myocardial perfusion, perfusion reserve, and coronary vascular resistance (CVR) in AF patients using positron emission tomography (PET). METHODS AND
RESULTS: Twenty-five male patients (age: 58 +/- 13 years) with persistent idiopathic AF were compared with 13 age- and risk-matched male controls (age: 56 +/- 8 years). Using H(2)(15)O-PET, myocardial blood flow (MBF) was quantified at rest, at hyperaemia (adenosine), and during cold-pressor-testing (CPT). Scans were repeated 4.1 +/- 2.3 months after cardioversion in 10 AF patients. In AF, resting MBF (0.95 +/- 0.19 vs. 1.14 +/- 0.22 mL/min/mL; P = 0.009), hyperaemic MBF (2.07 +/- 0.80 vs. 3.33 +/- 0.78 mL/min/mL; P < 0.001), and MBF under CPT (0.90 +/- 0.25 vs. 1.14 +/- 0.25 mL/min/mL; P < 0.014) were significantly reduced compared with matched controls. Hyperaemic CVR was increased in AF (47 +/- 21 vs. 29 +/- 7 mmHg x mL/min/mL; P = 0.012) but unchanged at rest and under CPT. After cardioversion, resting MBF and MBF under CPT in AF were similar to matched controls, however, hyperaemic MBF and CVR were not recovered.
CONCLUSION: In AF, MBF at baseline, at hyperaemia, and at CPT is reduced, whereas CVR under hyperaemic conditions is increased. Following electrical cardioversion, these findings are partly reversible and therefore most likely secondary to the arrhythmia.