Sinus rhythm maintenance following DC cardioversion of atrial fibrillation is not improved by temporary precardioversion treatment with oral verapamil.

OBJECTIVE: To evaluate prospectively the effects of pretreatment with verapamil on the maintenance of sinus rhythm after direct current (DC) cardioversion. DESIGN: Randomised, active control, open label, parallel group comparison of verapamil versus digoxin. SETTINGS: Multicentre study in three teaching and three non-teaching hospitals in Sweden. PATIENTS: 100 consecutive patients with atrial fibrillation (AF) of at least four weeks' duration and indications for cardioversion were assigned randomly to two groups, one treated with verapamil (verapamil group) and the other with digoxin (digoxin group) before cardioversion. Fifty patients were assigned randomly to each treatment arm. After dropout of four patients from the digoxin group and seven patients from the verapamil group, data obtained from 89 patients were analysed. INTERVENTIONS: After randomly assigned pretreatment with either verapamil or digoxin for four weeks, DC cardioversion was performed. If sinus rhythm was restored then verapamil treatment was discontinued. MAIN OUTCOME MEASURES: The rate of AF recurrence was assessed one, four, eight, and 12 weeks after cardioversion. RESULTS: 6 patients in the verapamil treated group and none in the digoxin treated group reverted to sinus rhythm spontaneously (p < 0.05). DC cardioversion restored sinus rhythm in 24 of 37 (65%) patients in the verapamil group and 41 of 46 patients (89%) in the digoxin group (p < 0.05). After 12 weeks' follow up 28% (13 of 46) of digoxin pretreated patients versus 9% (four of 43) of verapamil pretreated patients remained in sinus rhythm (p < 0.05). CONCLUSION: Pretreatment with verapamil alone does not improve maintenance of sinus rhythm after DC cardioversion in patients with AF. The rate of spontaneous cardioversion may be improved by verapamil.

Left atrial appendage outflow velocity index is superior to conventional criteria for prediction of maintenance of sinus rhythm after cardioversion. An echocardiographic study in patients with atrial fibrillation of a few months' duration.

OBJECTIVE: To investigate whether left atrial appendage outflow velocity alone or in relation to left atrial diameter is a superior predictor of sinus rhythm maintenance after cardioversion compared with traditional clinical or echocardiography parameters. DESIGN: Sixty-two patients with their first episode of atrial fibrillation were examined using echocardiography before DC-cardioversion. At one month's follow-up, 42 patients had maintained sinus rhythm (group A), and 20 had relapsed into atrial fibrillation (group B). There were no differences in arrhythmia duration or antiarrhythmic therapy between the groups. RESULTS: Left atrial diameter measured by echocardiography was smaller in group A (42 mm, 95% CI 40.9-44.1 mm) compared with group B (46 mm, 95% CI 43.4-48.2, p < 0.05). Patients in group A had a higher left atrial appendage outflow velocity at 0.44 m/s (95% CI 0.39-0.49) compared with 0.34 m/s (95% CI 0.30-0.37) in group B (p < 0.01). The ratio of left atrial appendage flow to left atrial diameter was 0.011 (95% CI 0.009-0.012) in group A compared with 0.008 (95% CI 0.007-0.009) in group B, and 63% (95% CI 33-78) of the patients in group A had velocity ratio >0.009 compared with 20% (95% CI 2-38) in group B, (p < 0.01). Stepwise multiple logistic regression analysis showed that a velocity ratio >0.009 was the only predictor for maintenance of sinus rhythm one month after cardioversion with an odds ratio of 6.4 (95% CI 1.9-23.8), (p = 0.004). CONCLUSION: The ratio of left atrial appendage outflow velocity to left atrial diameter is superior to the traditionally used criteria for prediction of maintenance of sinus rhythm following DC-conversion of first-episode atrial fibrillation.

Characterization of atrial fibrillation using the surface ECG: time-dependent spectral properties.

Time-frequency analysis is considered for characterizing atrial fibrillation in the surface electrocardiogram (ECG). Variations in fundamental frequency of the fibrillatory waves are tracked by using different time-frequency distributions which are appropriate to short- and long-term variations. The cross Wigner-Ville distribution is found to be particularly useful for short-term analysis due to its ability to handle poor signal-to-noise ratios. In patients with chronic atrial fibrillation, substantial short-term variations exist in fibrillation frequency and variations up to 2.5 Hz can be observed within a few seconds. Although time-frequency analysis is performed independently in each lead, short-term variations in fibrillation frequency often exhibit a similar pattern in the leads V1, V2 and V3. Using different techniques for short- and long-term analysis, it is possible to reliably detect subtle long-term changes in fibrillation frequency, e.g., related to an intervention, which otherwise would have been obscured by spontaneous variations in fibrillation frequency.

Diurnal variations of the dominant cycle length of chronic atrial fibrillation.

High-resolution digital Holter recording was carried out in 21 patients (15 men, 64 +/- 12 yr) with chronic atrial fibrillation. Dominating atrial cycle length (DACL) was derived by frequency domain analysis of QRST-reduced electrocardiograms. Daytime mean DACL was 150 +/- 17 ms, and nighttime mean was 157 +/- 22 ms (P = 0. 0002). Diurnal fluctuation in DACL differed among patients: it tended to be virtually absent in those with a short mean DACL, but in those with longer DACL the night-day difference was as much as 23 ms (R = 0.72, P < 0.001, correlation of mean DACL to night-day difference). Mean DACL also correlated with ventricular cycle length (R = 0.40, P < 0.001), particularly at night (r = 0.49). The shorter cycle lengths found in this study during the day are consistent with sympathetic and/or other physiological modulation, but since increased vagal tone shortens atrial refractoriness in most models, parasympathetic influences are not likely to play a major role. Alternatively, atrial effective refractory period may not be the sole determinant of atrial cycle length during atrial fibrillation.

Non-invasive assessment of atrial fibrillation (AF) cycle length in man: potential application for studying AF.

Non-invasive assessment of the fibrillatory frequency of atrial fibrillation (AF) can be performed by frequency domain analysis. The peak frequency in the derived spectrum can be converted to a dominant atrial cycle length (DACL). The DACL can be altered through autonomic modulation or pharmacologic manipulation, but the change in DACL is less marked in those with a short DACL value. In patients with AF, those with a short duration of the arrhythmia have longer DACL values. Finally, patients with paroxysmal AF generally exhibit longer DACL values than patients with permanent AF. Thus non-invasive assessment of the atrial fibrillatory cycle length provides a useful index of atrial refractoriness and has the potential of clinical utility in patient assessment and treatment planning.

Attenuation of electrical remodelling in chronic atrial fibrillation following oral treatment with verapamil.

AIMS: Electrical remodelling with shortening of the atrial refractory period and increased fibrillatory rate occurs after onset of atrial fibrillation and can be attenuated by pre-treatment with intravenous verapamil. The aim of the present study was to investigate whether already established fibrillatory-induced shortening of atrial fibrillatory cycle length could be reversed with oral verapamil. METHODS AND RESULTS: Thirteen patients (nine men; mean age 67 years) with chronic atrial fibrillation (CAF) were studied. The dominant atrial cycle length (DACL) was estimated non-invasively using the frequency analysis of fibrillatory ECG (FAF-ECG) method. Measurements were repeated following treatment with slow release oral verapamil. DACL increased from 147 +/- 13 ms to 156 +/- 21 ms after 1 day (P=0.02), to 164 +/- 18 ms after 5 days (P=0.005) and finally to 160 +/- 16 ms after 6 weeks (P=0.008). CONCLUSION: Long-term oral treatment with verapamil increases the DACL significantly in patients with CAF. The prolongation is evident after 1 day and is further developed during the first 5 days of treatment. Since DACL is believed to be an index of refractoriness, the findings of the present study suggest that this treatment increases the atrial refractory period in patients with CAF.