Effect of cardiac resynchronization on the incidence of atrial fibrillation in patients with severe heart failure.

BACKGROUND: Atrial fibrillation/flutter (AF) and heart failure often coexist; however, the effect of cardiac resynchronization therapy (CRT) on the incidence of AF and on the outcome of patients with new-onset AF remains undefined. METHODS AND RESULTS: In the CArdiac REsynchronisation in Heart Failure (CARE-HF) trial, 813 patients with moderate or severe heart failure were randomly assigned to pharmacological therapy alone or with the addition of CRT. The incidence of AF was assessed by adverse event reporting and by ECGs during follow-up, and the impact of new-onset AF on the outcome and efficacy of CRT was evaluated. By the end of the study (mean duration of follow-up 29.4 months), AF had been documented in 66 patients in the CRT group compared with 58 who received medical therapy only (16.1% versus 14.4%; hazard ratio 1.05; 95% confidence interval, 0.73 to 1.50; P=0.79). There was no difference in the time until first onset of AF between groups. Mortality was higher in patients who developed AF, but AF was not a predictor in the multivariable model (hazard ratio 1.17; 95% confidence interval, 0.82 to 1.67; P=0.37). In patients with new-onset AF, CRT significantly reduced the risk for all-cause mortality and all other predefined end points and improved ejection fraction and symptoms (no interaction between AF and CRT; all P>0.2). CONCLUSIONS: Although CRT did not reduce the incidence of AF, CRT improved the outcome regardless of whether AF developed.

Phase 2 reentry in man.

BACKGROUND: Ventricular extrasystoles are characterized by a fixed coupling interval to the last QRST complex preceding it. OBJECTIVES: We hypothesized that this QRST complex differed from QRST complexes of other sinus beats not followed by ventricular extrasystoles. Further, we investigated whether phase 2 reentry, demonstrated in animal experiments to initiate ventricular extrasystoles, ventricular tachycardia, and ventricular fibrillation, also plays a role in humans. METHODS: We examined 18 patients with ventricular extrasystoles and/or ventricular tachycardia by signal averaging of the ECG (group A) or by single-beat analysis of intracardiac electrograms (group B). Group A consisted of six patients without structural heart disease and one patient with the Brugada syndrome. Six of the seven patients had right ventricular outflow tract ventricular extrasystoles. Group B consisted of 11 patients undergoing radiofrequency ablation. Eight of the 11 patients had right ventricular outflow tract extrasystoles. RESULTS: In six of the seven patients in group A, we demonstrated significant ST-elevation and/or T-wave changes in the sinus beat preceding ventricular extrasystoles compared with the second last sinus beat in one or more of the three orthogonal leads X, Y, and Z. In 9 of the 11 patients in group B, single-beat analysis of unipolar and bipolar electrograms recorded close to successful ablation sites demonstrated similar changes, that is, ST-elevation (median peak voltage gradient 150 muV, range 0-1,700) and T-wave changes in the sinus beat prior to ventricular ectopy. In addition, J-point elevation was demonstrated in several cases. In total, significant changes were demonstrated in 15 of the 18 patients studied (83%). CONCLUSION: J-point elevation, ST-elevation, and T-wave changes documented in the last sinus beat prior to ventricular extrasystoles are in agreement with phase 2 reentry, suggesting that this may be the responsible mechanism for ventricular extrasystoles and ventricular tachycardia/fibrillation. The phenomenon has been demonstrated in only animal experiments to date.