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.

Vasoactive peptides during long-term follow-up of patients after cardiac transplantation.

BACKGROUND: Vasoactive peptides are accepted indicators of the degree of heart failure and its progression or improvement following medical therapy. Normalization of cardiac hemodynamics by cardiac transplantation (HTx) may lead to normalization of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) plasma levels shortly after the procedure. METHODS: Long-term follow-up was done for 14 consecutive patients, 12 men and 2 women, 49 years of age (range 24 to 64 years). ANP and BNP were measured by radioimmunoassay (RIA) in central venous plasma samples (before breakfast, at steady state) at the following intervals after HTx: 7 to 30 (1), 31 to 60 (2), 61 to 90 (3), 120 to 180 (4) and 210 to 365 (5) days. RESULTS: During follow-up, ANP decreased significantly within 2 months after HTx and continued of this level, whereas BNP decreased continuously without reaching normal values. The mean ratio of ANP:BNP increased from 3.23 to 8.01 during follow-up. Whereas right atrial pressure (RAP), right ventricular pressure (RVP), right ventricular end-diastolic pressure (RVEDP) and pulmonary capillary wedge pressure (PCWP) did not change during follow-up, cardiac output (CO) improved slightly, but significantly from 5.21 liters/min to 5.9 liters/min (p = 0.035). CONCLUSIONS: Normalization of left ventricular function after orthotopic HTx does not induce an early diminution of ANP and BNP plasma levels to normal concentrations. Although elevated ANP concentrations showed only minimal changes within 1 year, BNP decreased significantly as early as 2 months after HTx, without reaching normal values during the year of follow-up. Also, the ratio of ANP and BNP increased significantly from 3.23 to 8.01. These results demonstrate the contribution of other factors beyond cardiac function that determine the levels of these peptides.