P-wave abnormality predicts recurrence of atrial fibrillation after electrical cardioversion: a prospective study.

BACKGROUND: Maintenance of atrial fibrillation (AF) is related to atrial electrical inhomogeneity and resultant chaotic reentry. Our aim was to test the hypothesis that abnormalities of P morphology on the surface electrocardiogram (ECG) predict recurrent AF following electrical cardioversion (ECV). METHODS: A 12-lead ECG was recorded after ECV for persistent AF in 77 patients (51 men, 65 ± 10 years) and repeated 1 month later. P-wave duration was obtained in each lead using blinded on-screen measurement. Maximum P-wave duration (P-max) was defined as the longest measurable P-wave duration in any lead. P-wave dispersion (PWd) was calculated as the maximum-minimum P-wave duration. RESULTS: One month after ECV, 29 (38%) patients maintained sinus rhythm. Compared with the sinus rhythm group, those with recurrent AF had significantly greater PWd (66 ± 19 vs 57 ± 16 ms, P = 0.024) and included more patients with P-max ≥142 ms (65% vs 38%, P = 0.023). Using a cutoff of ≥62 ms for PWd and ≥142 ms for P-max, both indices had similar predictive value (sensitivity 66.7 and 64.6%, specificity 58.6 and 62.1%, respectively). In multiple regression analysis, including established clinical predictors, P-max ≥142 ms was the only independent predictor of AF recurrence (P = 0.025). CONCLUSION: A prolonged P-wave duration measured by 12-lead ECG predicts recurrent AF within 1 month after ECV.

Ventricular pauses during atrial fibrillation predict relapse after electrical cardioversion: a prospective study.

AIMS: To investigate the use of ambulatory electrocardiogram (ECG) monitoring in atrial fibrillation (AF) to predict recurrence after electrical cardioversion (ECV). METHODS: RR interval variables were obtained from 24 hours ECGs recorded before ECV in 119 patients (85 men, age 66 +/- 10 years) with persistent AF. Patients were followed for 1 month. RESULTS: Of the 119 patients, 16 (13%) failed ECV and 65 (55%) were in AF at 1 week and 81 (68%) at 1 month after ECV. The maximum RR interval (RR-max) and the minimum RR interval (RR-min) during AF were found to be reproducible. The RR-max was longer in those who had AF 1 week (2.55 +/- 0.49 vs 2.01 +/- 0.52 seconds, P = 0.005) and 1 month (2.56 +/- 0.50 vs 1.89 +/- 0.43 ms; P < 0.001) after ECV than in those who maintained sinus rhythm. Those in AF at 1 month included more patients with RR-max > or = 2.8 seconds (31% vs 11% P = 0.021). The average heart rate was lower in patients with RR-max > or = 2.8 seconds, but the average rate was not predictive of AF recurrence. CONCLUSION: Ventricular pauses during AF predict relapse after ECV.

A distinctly bimodal distribution pattern in the RR interval histogram predicts early recurrence of atrial fibrillation after electrical cardioversion.

Abnormal AV nodal behaviour could contribute to recurrence of Atrial Fibrillation (AF) after electrical cardioversion (ECV). We constructed RR interval histograms from 24-hour ECGs recorded before ECV in 98 patients with persistent AF. RR histograms were classified as unimodal or bimodal, and bimodal histograms classified into distinctly or indistinctly bimodal. At 1 week after ECV, 52 patients (53%) were in AF and at one-month 66 (67%) were in AF. A bimodal RR interval distribution during AF was found in 17 patients (18%), a distinctly bimodal RR histogram in 8 of these (47%). Compared to those with indistinct bimodality, patients with a distinctly bimodal RR histogram were more likely to have AF at one-week and one-month (88 vs. 33%, 100 vs. 33%, p=0.01, p=0.009, respectively).

Distribution and prognostic significance of QT intervals in the lowest half centile in 12,012 apparently healthy persons.

The presence of an abnormally short QT interval has been noted among survivors of idiopathic ventricular fibrillation and among close relatives of victims of unexplained sudden death. Most reported cases have had rate-corrected QT (QTc) intervals of <300 ms. The prevalence of such values in the community has not been documented. We reviewed the electrocardiograms (ECGs) of 12,012 subjects who underwent routine medical examinations for occupational reasons. The QT interval was measured by 2 physicians in all cases, and QTc interval was calculated. All ECGs with QTc values in the lowest 5% were reviewed by 2 cardiologists expert in QT analysis, and the QT measurement was corrected if necessary. Information about subsequent survival was obtained from the case file or from public records. In the lowest 1/2 centile, the distribution of QTc values continued to follow a normal pattern without evidence of a distinct subpopulation of low values. The shortest QTc encountered was 335 ms. Information about subsequent survival was available for 36 of the 60 subjects with the lowest 1/2 centile of QTc values. None of these subjects died during the 7.9 +/- 4.5 years subsequent to the ECG that demonstrated the short QT interval. In conclusion, a QTc interval of

Prognostic significance of serial P wave signal-averaged electrocardiograms following external electrical cardioversion for persistent atrial fibrillation: a prospective study.

The authors hypothesized that the persistence of abnormal atrial conduction detected by serial P wave signal-averaged electrocardiograms (P-SAECGs) can identify patients who are at high risk of recurrent atrial fibrillation (R-AF) following electrical cardioversion (ECV). P-SAECGs were recorded in 60 consecutive patients after ECV (53 men, age 66 +/- 10 years) and repeated in those who had remained in sinus rhythm (SR) 1 week, and 1, 3, and 6 months later. Filtered P wave duration (PD), root mean square (RMS) voltage of the terminal 40, 30, 20 ms (RMS-40, RMS-30, RMS-20) of the filtered P wave, RMS voltage of the entire filtered P wave (RMS-p), and the integral of the voltages in the entire P wave (integral-p) were analyzed. Thirty-one (52%) patients returned to AF within 1 week, an additional 11 (18%) by 1 month, and a further 2 (3.3%) at each subsequent assessment (3 and 6 months). The patients with R-AF had longer PD (157 +/- 24 vs 143 +/- 17 ms, P < 0.0001) and lower RMS-40, RMS-30, RMS-20 (5.3 +/- 2.0 vs 6.1 +/- 3.4 microV, P = 0.007; 4.3 +/- 1.5 vs 5.7 +/- 3.2 microV, P < 0.0001; 3.6 +/- 1.4 vs 5.2 +/- 3.0 microV, P < 0.0001, respectively) than those who remained in SR. These measurements did not change significantly in either group. RMS-p increased in SR patients (P = 0.009) but decreased in those who subsequently reverted to AF (P = 0.032) with a significant difference between the slopes of the RMS-p change (P = 0.006). Integral-p decreased from the time of ECV in the R-AF group only (P = 0.0028) and created a significant difference between the two slopes (P = 0.0004). The evolution of P-SAECG parameters after ECV differs in patients whose AF recurs versus patients who remain in SR.