UNLABELLED

The hemodynamic consequences of atrial fibrillation (AF) may lead to impairment of the left ventricular function and a reduction in exercise capacity. Studies on mechanical and neurohormonal remodelling in patients with AF are becoming increasingly important. The results could possibly enhance treatment strategies of these patients. The aim of this study was to assess changes in exercise capacity, echocardiographic findings and plasma atrial natriuretic peptide (ANP) concentrations in patients with non-rheumatic persistent AF, before and 30 days after successful cardioversion.

METHODS

We attempted cardioversion in 42 consecutive patients, aged 58 +/- 8 years, with persistent non-valvular AF of duration 7.1 +/- 7.1 months. They underwent echocardiography examination and submaximal exercise testing 24 h before and 30 days after cardioversion. Exercise capacity was determined during symptom-limited exercise testing, according to a modified Bruce protocol with peak VO2 analysis. Plasma samples of ANP were obtained at rest: before, the day after, and 30 days after cardioversion therapy, and were prepared by refrigerated centrifugation and stored until radioimmunoassay. The control study group, without AF, comprised of 11 subjects.

RESULTS

Cardioversion was successful in 35 patients. However, in six of the 35 patients, AF reappeared within 1 month. There were no statistical differences before cardioversion in exercise tolerance and ejection fraction of left ventricle between the group with successful cardioversion and the group with unsuccessful cardioversion or with recurrence of AF. On the 30th day after cardioversion we recorded a significant increase in exercise tolerance: duration of exercise 13.7 +/- 3.2 versus 9.5 +/- 3.4 min, (P < 0.05); peak oxygen consumption 32.2 +/- 3.6 versus 19.85 +/- 3.5 ml/min per kg, (P < 0.05); and ejection fraction of left ventricle 58.6 +/- 9.4 versus 52.7 +/- 10.2% (P < 0.05); in the sinus rhythm group. There was no significant improvement observed in the AF group. The mean baseline ANP level was 58.5 +/- 15.7 pg/ml in the study group and 34.3 +/- 10.2 pg/ml in the control group (P < 0.01). The successful therapy reduced significantly the pretreatment mean plasma ANP concentration from 58.5 +/- 15.7 to 31.4 +/- 15.0 pg/ml, (P < 0.01); the day after cardioversion, in the group of 35 patients. It remained stable for the next 30 days (36.9 +/- 15.2 pg/ml) in the group of 29 patients who remained in sinus rhythm, and increased to 53.4 +/- 16.4 pg/ml in the group of six patients who had recurrence of AF. Plasma ANP did not change in the group of seven patients with unsuccessful cardioversion.

CONCLUSIONS

The restoration of sinus rhythm in patients with persistent AF was associated with a significant improvement in cardiac performance and exercise tolerance 1 month after cardioversion. Such improvement was not observed in the group with unsuccessful cardioversion or with AF recurrence. The plasma ANP concentration in patients with AF was significantly reduced after successful cardioversion and remained stable for a period of 30 days.