Clinical, adrenergic and heart endocrine measures in chronic atrial fibrillation as predictors of conversion and maintenance of sinus rhythm after direct current cardioversion

The aim of this study was to evaluate clinical, adrenergic andendocrine factors that could predict sinus rhythm maintenanceafter direct current cardioversion in chronic atrial fibrillation. Nineteen patients with chronic non-rheumatic atrial fibrillation(mean duration 6±5 months) were studied. They were exercised24 h before cardioversion at maximum effort with the Naughtonprotocol. Heart rate and blood pressure at rest and exercisewere recorded and blood samples were taken for the assessmentof adrenergic activity, by measuring cyclic adenosine monophosphate,heart endocrine function, atrial natriuretic peptide and itssecond messenger, cyclic guanosine monophosphate. Fifteen ofthe 19 patients were initially converted to sinus rhythm (eightpatients with external and seven patients with internal DC shocks).After 3 months eight patients remained in sinus rhythm and 11had relapsed, most of them within the first month. On exercisethe chronotropic response was lower in the group who remainedin sinus rhythm than in the group in atrial fibrillation (peakheart rate 147±11 beats.min^–1 vs 165±24beats.min^–1 p=0·02). During exercise, the systolicblood pressure in the sinus group reached higher values thanin the group who relapsed (192±17 mmHg vs 176±18mmHg, p=0·03). Cyclic adenosine monophosphate increasedsignificantly from rest to peak exercise in the sinus rhythmgroup (from 23±9 pmol.ml^–1 to 31±15 mol.ml^–1,p=0·02) while it remained unchanged in the atrial fibrillationgroup (25±10 pmol.ml^–1 to 24±8 pmol.ml^–1,p=0·02). For all 19 patients the differ ence in cyclicadenosine monophosphate between rest and exercise was negativelycorrelated with maximum heart rate (r=0·58, p=0·009).Atrial natriuretic peptide increased from rest to peak exercisein the sinus rhythm group (from l29±58 fmol.ml^–1to 140±66fmol.ml^–1 while it remained unchangedin the group in which atrial fibrillation persisted or recurred(from 112±58 fmol.ml^–1 to 111±53 fmol.ml^–1p=0· A significant correlation between atrial natriureticpeptide and cyclic guanosine monophosphate levels at exercisebefore cardioversion was found for the sinus rhythm group only(r=0·76, p=0·02). In patients with non-rheumatic chronic atrial fibrillation evaluationof clinical parameters such as heart rate and blood pressurechanges during maximal exercise can be useful in the choiceof suitable therapy. An inadequate increase in plasma cyclic-adenosinemonophosphate and atrial natriuretic peptide on exercise couldpredict patients with more severe underlying disease, wherecardioversion should not be recommended.