CGMP Levels Following ANF Challenge are Markers of Subsequent Successful Reversion of Lone Atrial Fibrillation to Sinus Rhythm THEONI MESISKLI, PANAGIOTA G. FLEVARI, EFTHIMIOS G. LIVANIS, ELIAS BOFILIS, MD, GEORGE N. THEODORAKIS, DIMITRIOS TH. KREMASTINOS 2 Department of Cardiology, Onassis Cardiac Surgery Center, Athens, Greece MESISKLI, T., ET AL.: CGMP Levels Following ANP Challenge are Markers of Subsequent Successful Rever- sion of Lone Atrial Fibrillation to Sinus Rhythm. The aim of the present study was to as.sess whether cGMP release to ANP stimulation can be a biochemical marker of subsequent successful electrical cardioversion of lone atrial fibril- lation to sinus rhythm. Eor this purpose, we studied 13 patients with chronic, lone atrial fibrillation of less than one year's duration who presented to our laboratory for electrical therapy of their arrhythmia. Prior to electrical car- dioversion, peripheral venous cGMP levels were assessed at baseline andfollowing an tntravenous challenge of 50 Vg human ANP. Venous blood samples for cGMP assessment were taken a) at baseline . b) 5 and 10 mins after the end of ANP infusion. ANOVA of repeated measures was usedfor statistical analysis. Eight of the study patients were .success- fully cardioverted to sinus rhythm, while the remaining 5 were not. Although no difference was noted between the two groups regarding the mean time of arrhythmia duration as well as left atrial and ventricular dimensions, ANP stimula- tion provoked significantly greater cGMP release in patients whose arrhythmia reverted to sinus rhythm, when com- pared with that of patients whose arrhythmia persisted (p<O.OOI). Therefore, cGMP levels following ANP challenge might discriminate between patients with chronic AF who are going to be successfully cardioverted and those who are not. These findings imply that the underlying atrial disease might be different in extent/nature between patients with lone AF responsive to cardioversion and those with resistant arrhythmia. cGMP, ANP, atrial fibrillation, cardioversion, sinus rhythm Introduction Although the electrical cardioversion of atrial fibrillation (AF) is a common procedure, it is still difficult to discriminate between patients who are going to be successfully cardioverted to sinus rhythm and those who are not. Various clinical pa- rameters, such as AF duration and left atrial diame- ter, have been studied as possible predictors of suc- cessful subsequent cardioversion to sinus rhythm, but their predictive value is low. We have previ- ously shown that, in patients whose arrhythmia is going to be successfully cardioverted to sinus Address for reprints: George N. Theodorakis, MD, Onassis Cardiac Surgery Center, 356 Sygrou Ave, 176 74 Athens, Greece. Fax: +30-1-9393 331. e-mail: elbee@ath.forthnet.gr rhythm, atrial natriuretic peptide (ANP) plasma lev- els increase during exercise, while they remain un- changed in patients whose arrhythmia persists or recurs. It is not known if a similar difference exists, too, in the ANP-induced plasma release of cyclic guanosine monophosphate (cGMP), the second ANP messenger.^^ In this study, we evaluated pa- tients with chronic, lone AF to assess whether cGMP release to ANP stimulation can be a bio- chemical marker of subsequent successful electrical cardioversion of lone AF to sinus rhythm. Patients and Methods Thirteen consecutive patients with chronic, lone AF were included in the study. The mean duration of their arrhythmia was 5 ± 3 months (range: 2 168 January 1998, Part n PACE. Vol. 21