Ventricular Proarrhythmic Effects of Atrial Fibrillation are Modulated by Depolarization and Repolarization Anomalies in Patients with Left Ventricular Dysfunction

Background: Atrial fibrillation (AF) may have a ventricular proarrhythmic effect, particularly in the setting of heart failure. We assessed whether AF predicts appropriate implantable cardioverter-defibrillator (ICD) shocks in patients with left ventricular dysfunction and explored modulators of risk.
Methods and Results: A retrospective cohort study was conducted on 215 consecutive patients with ICDs for primary prevention having a left ventricular ejection fraction ≤ 35%. Mean age at ICD implantation was 61.0 ± 9.7 years and 17% were women. Overall, 22 patients (10.2%) experienced appropriate ICD shocks over a follow-up of 1.3 ± 0.7 years, corresponding to an actuarial event-rate of 5.8% per year. In univariate analysis, AF was associated with a 3.6-fold increased risk of appropriate shocks (P = 0.0037). Annual rates of appropriate ICD shocks in patients with and without AF were 12.9% and 3.5%, respectively (P = 0.0200). In multivariate stepwise Cox regression analyses controlling for baseline imbalances, demographic parameters, underlying heart disease, and therapy, history of AF independently predicted appropriate shocks (hazard ratio 2.7, P = 0.0278). Prolonged QRS duration (>130 ms) and QTc (>440 ms) modulated the effect of AF on appropriate shocks. Patients with both AF and QRS > 130 ms were more than five times more likely to receive an appropriate ICD shock (hazard ratio 5.4, P = 0.0396). Patients with AF and QTc > 440 ms experienced a greater than 12-fold increased risk of appropriate shocks (hazard ratio 12.7, P = 0.0177).
Conclusion: In prophylactic ICD recipients with left ventricular dysfunction, AF is associated with increased risk for ventricular tachyarrhythmias, particularly when combined with conduction and/or repolarization abnormalities.     

Does Atrial Fibrillation Beget Ventricular Fibrillation in Patients with Acute Myocardial Infarction?

Background: Atrial fibrillation (AF) is associated with increased mortality and a higher complication rate postmyocardial infarction (MI), but the exact mechanisms are unknown. We investigated whether AF predisposes to ventricular arrhythmia in postmyocardial infarct patients, thereby accounting for increased mortality. Methods: Five hundred consecutive patients admitted to our coronary care unit with acute MI were monitored for in‐hospital arrhythmias. Detailed information was also compiled on past history, co‐morbidities, electrolyte disturbances, drug therapies, and ejection fraction. Mortality data were collected for an average of 5.5 years. Results: The results have shown that the incidence of ventricular fibrillation (VF) is much greater in patients presenting with AF (P = 0.03) and multivariate analysis has shown that AF is independently associated with the development of VF. This association occurs principally in patients who are admitted with AF (P = 0.01) rather than those who develop it during their admission, although these patients are also at mildly increased risk. The increased incidence of VF does account for increased mortality in the AF patients but does not explain all of their excess risk. There was no association between AF and ventricular tachycardia (VT); P = 0.50. Conclusions: In conclusion, AF on admission to the hospital with acute MI is associated with an increased risk of VF and subsequent mortality.     

Amiodarone in the Management of Patients with Ventricular Tachycardia and Ventricular Fibrillation

Fifty-eight patients with symptomatic ventricular tachycardia (VT) or ventricular fibrillation (VF) were treated with amiodarone. All had clinical episodes of VT/VF or inducible VT during electropharmacologic testing despite treatment with maximumtolerated doses of conventional antiarrhythmic agents. Chronic treatment with amiodarone was begun at a dose of 800–1000 mg per day. Thirty-two patients were also treated with a previously ineffective conventional agent. Thirty patients underwent programmed ventricular stimulation after 2.6 ± 1.7 months (mean ± S. D.) of treatment with amiodarone at a mean daily dose of 588 ± 155 mg. VT was induced in 25 patients (sustained in 20, nonsustained in five). Seventeen patients had a recurrence of VT or VF after 0.5–9 months of treatment with amiodarone (fatal in seven, non-fatal in 10). Forty-one patients (71%) had no recurrence of symptomatic VT or VF while being treated with amiodarone (mean follow-up period, 17.1 ± 12.4 months). Among the 25 patients who had inducible VT with programmed ventricular stimulation while being treated with amiodarone, 19 patients (76%) have had no recurrence of symptomatic VT or VF overa follow-up period of 21.5 ± 7.3 months. Ambulatory electrocardiographic recordings obtained after one week of treatment with amiodarone were not helpful in predicting clinical response. Twenty-two patients (38%) developed ataxia and/or an intention tremor which improved with a decrease in the amiodarone dose. Amiodarone, either by itself or in combination with conventional antiarrhythmic drugs, has a significant therapeutic effect in high risk patients with refractory VT. The finding of inducible VT during electropharmacologic testing in patients taking amiodarone does not preclude a favorable clinical response. Neurologic toxicity is common in patients treated with 600–800 mg per day of amiodarone.     

The Value of Rate Regularity and Multiplicity Measures to Detect Ventricular Tachycardia in the Presence of Atrial Fibrillation or Flutter

The predominant cause of inappropriate therapy by implantable antitachycardia devices with pacing and nonpacing cardioverter defibrillators, is mistaking a fast ventricular response during atrial fibrillation or flutter with true ventricular tachycardia (VT). The distinction between these arrhythmias is an important consideration in addressing the problem of reducing false-positives in detection mechanisms for implantable devices. Dual chamber analysis that examines atrial and ventricular event ratios has been proposed as a solution to this problem, but would still fail in distinguishing paroxysmal VT requiring treatment from a fast but otherwise benign ventricular response during atrial fibrillation or flutter. In this study, two methods for discriminating these tachyarrhythmias were evaluated. Method 1 examined ventricular rate and rate regularity as a method for VT detection. Method 2 combined rate and regularity as well as an additional multiplicity criterion for recognition of atrial flutter with a fast ventricular response. In 20 patients. Method 1 had 100% sensitivity of VT detection and 80% specificity for detection of atrial fibrillation or flutter. Method 2 had 90% sensitivity and 90% specificity. These results suggest that use of these algorithms in future implantable devices would result in a decrease in false-positive device therapies.     

Safety of High Energy Internal Cardioversion for Atrial Fibrillation

High energy internal cardioversion has been proposed as an alternative method to cardiovert drug refractory or external cardioversion refractory atrial fibrillation. However, the safety of this technique has not been clearly evaluated. We reviewed findings in 53 patients who underwent 55 sessions of high energy internal cardioversion (2 patients underwent 2 sessions] for termination of longstanding atrial fibrillation. Shocks energy varied from 70–270 J. Three patients had 3 shocks during the same session, 5 had 2, and 47 only 1. Success rate was 89% (success was defined as immediate conversion to normal sinus rhythm).
Low cardiac output occurred in two patients, and resulted in the death of one of these individuals, a patient with significant hypertrophic cardiomyopathy and heart failure. The other patient recovered completely. In 11% of the cases, shock induced transient atrioventricular block, necessitating ventricular pacing until sinus rhythm was restored. In three patients, a moderate but asymptomatic and uncomplicated pericardial effusion was diagnosed on echocardiogram. Finally, four patients had side effects related to venous puncture, which resolved spontaneously. These results suggest that high energy internal cardioversion is effective for conversion of atrial fibrillation. However, the technique may not be optimal in patients with advanced hypertrophic cardiomyopathy and in such cases the technique should be used carefully and only in the case of failure of external cardioversion; no more than two shocks should be delivered during the same procedure. Temporary ventricular pacing should be provided in all patients and an echocardiogram should be performed before patients are being discharged.     

Optimized Standby Rate Reduces the Ventricular Rate Variability in Pacemaker Patients with Atrial Fibrillation

Patients with chronic atria! fibrillation (AF) and symptomatic bradycardia often receive ventricular-based pacemakers. However, many of these patients continue to have symptoms of palpitations, which may be due to ventricular rate variability. It has previously been shown that contin uous ventricular pacing during AF has a stabilizing effect on the ventricular rate. Hence, a study was initiated to determine whether a patient-specific optimal ventricular standby rate that reduces the ventricular rate variability, without over-pacing, could be predicted. A ventricular rate stabilization (VRS) pacing algorithm that increases the pacing rate until instability is reduced below a threshold was developed. The VRS algorithm was utilized to determine a patient-specific standby rate in 15 patients with chronic AF, intact AV nodal conduction, and implanted pacemakers. The computer algorithm controlled a pacemaker programmer to automatically change the pacemaker's ventricular pacing rate via telemetry. Patients were studied for 15 minutes with VRS and for 15 minutes with 50 ppm fixed rate pacing (control). The results were as follows: (1) VRS versus control = P < 0.05; (2) mean ventricular pacing rate (ppm): 77 ± 13 versus 50 ± 0; (3) mean ventricular rate (beats/mm); 82 ± 13 versus 79 ± 12; (4) ventricular rate coefficient of variation (%): 11 ± 1 versus 22 ± 5; (5) percent pacing: 75 ± 8 versus 6 ± 8; (6) percent of RR intervals less than minimum pacing interval eliminated: 58 ± 12; (8) regression analysis: mean VRS pacing rate (beats/min) = 0.96 X mean control ventricular rate + 2.3, r²= 0.85. We concluded that: (1) a moderate increase in the ventricular pacing rate was required to substantially stabilize the ventricular rate; (2) the resulting mean ventricular rate increased marginally: (3) a majority of RR cycles less than each patient's minimum pacing interval were eliminated; and (4) there was a linear relationship between the mean ventricular rate during control and the optimal ventricular pacing rate. Thus, a ventricular pacing rate close to the mean ventricular rate during control consistently reduced the ventricular variability. Although pacing at an increased ventricular standby rate reduces variability at rest, the optimal solution would likely be an adaptive rate algorithm that changes the ventricular standby rate as the mean intrinsic rate varies.     

Serum Electrolytes and Catecholamines After Cardioversion From Ventricular Tachycardia and Atrial Fibrillation

We have observed hypokalemia after cardioversion from spontaneous out-of-hospital ventricular fibrillation and induced ventricular tachycardia. To test the hypothesis that the hormone response to the hemodynamic stress of the arrhythmia initiated the change in potassium, we compared the electrolytes and hormones in three groups of patients. We observed a decrease in serum potassium and magnesium after cardioversion from ventricular tachycardia induced by programmed Stimulation but not after normal programmed stimulation of the ventricle or after cardioversion from stable atrial fibrillation. These changes were preceded first by a rise in norepinephrine and epinephrine then a rise in glucose, followed by a rise in insulin. The stimulus for these changes was probably the hypotension associated with ventricular tachycardia. The sequence of changes suggests that the decrease of potassium and magnesium after ventricular tachycardia was due to a shift of the electrolytes into cells related to the insulin-mediated movement of glucose from the blood into cells.     

Low Energy Intracardiac Cardioversion of Persistent Atrial Fibrillation

The aims of the study were to verify the efficacy and safety of low energy internal Cardioversion (LEIC) in patients with persistent at rial fibrillation (AF) and to identify the factors affecting the at rial defihrillation threshold (ADT). Forty-nine patients with persistent (lasting ≥ 10 days) AF underwent LEIC. In each patient, two 6 Fr custom-made catheters with large active surface areas were positioned in the coronary sinus (cathode) and the lateral right wall (anode), respectively, for shock delivery, and a tetrapolar lead was placed in the fight ventricular apex for R wave synchronization. Truncated, biphasic (3 ms+3 ms). exponential shocks were used, beginning at 50 V and increasing in steps of 50 V until sinus rhythm had been restored. Mild sedation (diazepam 5 mg IV) was administered to 12 patients. Sinus rhythm was restored in all the subjects with mean voltage and energy levels of 352.0 ± 80.3 V and 8.2 ± 3.4 J, respectively. The ADT in patients pretreated with amiodarone (6.4 ± 1.8 J) was lower than that of patients who had not received any antiarrhythmic drugs (9.2 ± 3.7) (P = 0.04). No ventricular arrhythmias were induced by any of the atrial shocks, and no other complications were observed. During a mean follow-up of 162.9 ± 58.7 days, AF recurred in 21 (43%) patients; 71% of these occurred in the first week after Cardioversion. LEIC is effective in restoring sinus rhythm in patients with persistent AF. The technique seems to be safe and does not require general anesthesia or, in most cases, sedation. Patients pretreated with amiodarone have lower ADTs.     

Rounded Biphasic Waveform Reduces Energy Requirements for Transvenous Catheter Cardioversion of Atrial Fibrillation and Flutter

We postulated that reducing peak leading edge shock voltage and its rate of rise (waveform rounding) would reduce energy requirements for cardioversion of AF and AFI, and may therefore reduce patient discomfort. Transvenous defibrillating catheters (In-Control Inc.) were placed in the RAA (active fixation) and the CS of six anesthetized sheep. AF or AFI was induced by electrical stimulation (100 Hz, 2 V; Grass stimulator). A standard trapezoidal biphasic (S) waveform (3-ms duration each phase) was compared with a similar waveform that had the first phase rounded (R). Cardioversion was attempted after 30 seconds of arrhythmia, using a Ventritex HVS-O₂ defibrillator modified to allow waveform rounding. Each waveform was randomly tested several times at 100-, 150-, and 200-V leading edges, and percentage cardioversion success calculated. Shock energy was calculated from delivered current and voltage using Flukeview (Fluke, Inc.) software. At 100-V leading edge R (64% success) and S (59%), shocks were similarly efficacious (P = 0.37). However. R delivered less current, voltage, and energy than the comparable S shock (means 1.30 A, 65.0 V, 0.33 J R vs 1.92 A, 94.2 V, 0.47 J S; P = 0.0001). Both waveforms were equally successful at 150 V (88% vs 100%; P = NS) and 200 V(100% vs 100%), but again R delivered less current, voltage, and energy (2.05 A, 102.5 V, 0.82 J R vs 2.78 A, 142.3 V, 1.11 J S at 150 V; 2.76 A, 141.2 V, 1.58 J R vs 3.77 A, 189.4 V, 2.03 J S at 200 V; both P = 0.0001). No arrhythmic or other complications occurred in the 174 shocks delivered. Waveform rounding reduces delivered peak voltage, current, and energy without reducing defibrillation efficacy. To determine if these changes are associated with a reduction in discomfort, patients with AF are currently being cardioverted with these waveforms during electrophysiological studies.     

Low Energy Internal Atrial Cardioversion in Atrial Fibrillation Lasting More Than a Year

The aim of this study was to evaluate the efficacy of low energy internal atrial cardioversion in restoring sinus rhythm (SR) in patients with chronic atrial fibrillation (AF) persisting > 1 year. Fifteen patients with chronic AF lasting > 1 year (from 13–48 months, mean 24 ± 13 months) were studied. R wave synchronized 3/3 ms biphasic shocks were delivered between right atrial and coronary sinus (left pulmonary artery in five patients) electrodes. Sedatives or anesthetics were administered only at the patient's request. Results: Stable SR was restored in 14 (93%)of 15 patients after shocks with a mean leading edge voltage of 377 ± 77 V (range 260–500) and a mean delivered energy of 7.3 ± 3.4 J (range 2.6–12.9). The procedure was performed without anesthesia in 6 (40%) patients. All successfully cardioverted patients were treated with flecainide, sotalol, or amiodarone. During a follow up of 7.7 ± 7.9 months (range 1–24) AF recurred in five (36%) patients. Three of five AF recurrences occurred within 3 days after conversion to SR. Conclusion: Internal low energy atrial cardioversion is highly effective in restoring SR even in patients with AF lasting > 1 year. The long-term results from the standpoint of freedom from AF recurrences, are satisfactory, although additional antiarrhythmic treatment is required, particularly in the first days after conversion.     

Impact of Right Ventricular Pacing Sites on Exercise Capacity during Ventricular Rate Regularization in Patients with Permanent Atrial Fibrillation

Background: The deleterious effects of right ventricular apical (RVA) pacing may offset the potential benefit of ventricular rate (VR) regularization and rate adaptation during an exercise in patient's atrial fibrillation (AF). Methods: We studied 30 patients with permanent AF and symptomatic bradycardia who receive pacemaker implantation with RVA (n = 15) or right ventricular septal (RVS, n = 15) pacing. All the patients underwent an acute cardiopulmonary exercise testing using VVI‐mode (VVI‐OFF) and VVI‐mode with VR regularization (VRR) algorithm on (VVI‐ON). Results: There were no significant differences in the baseline characteristics between the two groups, except pacing QRS duration was significantly shorter during RVS pacing than RVA pacing (138.9 ± 5 vs 158.4 ± 6.1 ms, P = 0.035). Overall, VVI‐ON mode increased the peak exercise VR, exercise time, metabolic equivalents (METs), and peak oxygen consumption (VO₂max), and decreased the VR variability compared with VVI‐OFF mode during exercise (P < 0.05), suggesting that VRR pacing improved exercise capacity during exercise. However, further analysis on the impact of VRR pacing with different pacing sites revealed that only patients with RVS pacing but not patients with RVA pacing had significant increased exercise time, METs, and VO₂max during VVI‐ON compared with VVI‐OFF, despite similar changes in peaked exercise VR and VR variability. Conclusion: In patients with permanent AF, VRR pacing at RVS, but not at RVA, improved exercise capacity during exercise.     

Occurrence of Atrial Fibrillation in Patients With Paroxysmal Supraventricular Tachycardia Due to Atrioventricular Nodal Reentry

The occurrence of atrial fibrillation in patients with paroxysmal supraventricular tachycardia (PSVT) has been well documented when PSVT is secondary to atrioventricular reentry, but not when PSVT is secondary to atrioventricular nodal reentry (AVNRT). Seventeen patients with AVNRT were followed using transtelephonic electrocardiogram monitoring to document symptomatic tachycardias. The median length of telephone monitor surveillance was 357 days. Fifteen of 17 patients transmitted electrocardiograms that showed PSVT. Three of 17 patients (18%) transmitted electrocardiograms that showed atrial fibrillation. A transition from PSVT into atrial fibrillation was not recorded, but all three did have PSVT recorded on other days of follow-up. We report the occurrence of atrial fibrillation in patients with AVNRT and that its incidence is higher than expected for the general population.     

Efficacy of Ventricular Rate Stabilization by Right Ventricular Pacing During Atrial Fibrillation

To assess the effect of right ventricular pacing on rate regularity during exercise and daily life activities, 16 patients with sinoatrial disease and chronic atrial fibrillation (AF) were studied. Incremental ventricular pacing was commenced at 40 beats/min until > 95% of ventricular pacing were achieved during supine, sitting, and standing. Thirteen patients also underwent randomized paired submaximal exercise tests in either a fixed rate mode (VVI) or a ventricular rate stabilization (VRS) mode in which the pacingrate was set manually at 10 beats/min above the average AF rate duringthe last minute of each exercise stage. The pacing interval for rate regularization was shortest during standing (692 ± 26 ms) compared with either supine or sitting (757 ± 30 and 705 ± 26 ms, respectively, P < 0.05). During exercise, VRS pacing significantly increased the maximum rate (119 ± 5.2 vs 106 ± 4.2 ms, P < 0.05), percent of ventricular pacing (85%± 5% vs 23%± 7%, P < 0.05), rate regularity index (5.8%± 1.6% vs 13.4%± 1.9%, P < 0.05), and maximum level of oxygen consumption (12.4 ± 0.5 vs 11.3 ± 0.5 ml/kg, P < 0.05) compared with VVI pacing. There was no change in oxygen pulse or difference in symptom scores in this acute study between the two pacing modes. It is concluded that right ventricular pacing may significantly improve rate regularity and cardiopulmonary performance in patients with chronic AF. This may be incorporated in a pacing device for rate regularization of AF using an algorithm that is rate adaptive to postural and exercise stresses.     

Combined Cardiomyopathy and Skeletal Myopathy: A Variant with Atrial Fibrillation and Ventricular Tachycardia

VLAY, S., et al. : Combined Cardiomyopathy and Skeletal Myopathy: A Variant with Atrial Fibrillation and Ventricular Tachycardia. This article describes a family characterized by combined cardiomyopathy and nonspecific skeletal myopathy who present in the third to fifth decades with cardiac manifestations but earlier have evidence of subtle skeletal muscle dysfunction. They differ from previously defined syndromes and potentially represent a different genetic expression or mutation. Cardiomyopathy presents with atrial arrhythmias including AF and atrial flutter. Life-threatening ventricular tachyarrhythmias occur next with onset of ventricular dysfunction. Electrophysiological study revealed sustained monomorphic VT. Affected family members benefitted from an ICD and progression to congestive heart failure (CHF) occurred late. Skeletal myopathy continues with marked progressive muscle weakness and inability to ambulate without assistance. Genetic analysis is currently ongoing. Neurological evaluation in all three family members revealed nonspecific myopathy affecting the psoas and iliopsoas muscles. Atrophy and wasting of the facial and temporalis muscles were common. Skeletal muscle biopsy revealed myofiber atrophy consistent with myopathy.     

Pain Threshold for Low Energy Intracardiac Cardioversion of Atrial Fibrillation with Low or No Sedation

Recent studies have shown that internal cardioversion of atrial fibrillation is safe and effective. In this randomized prospective study, we have tried to evaluate the influence of different waveforms on the perception of pain during internal cardioversion in patients with chronic atrial fibrillation. Methods: Internal cardioversion was performed with minimal or no sedation in 31 consecutive patients, R wave triggered, biphasic shocks of 6 ms/6 ms or 3 ms/3 ms duration (randomly selected) and approximately 65% tilt were used starting with a 50-V test shock. The shock intensity was increased in 40-V steps up to a maximum voltage of 520 V. Shocks were applied via two custom-made catheters (Elecath, Rahway, NJ). In 16 patients (3 females, age 61 ± 11 years, left atrium diameter 58 ± 5 mm, duration of atrial fibrillation 4 ± 4 months), 6/6 waveforms were used, and in 15 patients (1 female, age 62 ± 5 years, left atrium diameter 59 ± 4 mm, duration of atrial fibrillation 5 ± 2 months), 3/3 waveforms were used. After cardioversion, each patient was asked to quantify their pain on a scale from 0–10 (0 = no pain, 10 = intolerable). Fourteen of the 15 patients in the 3/3 ms and 15 of the 16 patients in the 6/6 ms group were successfully cardioverted. Patients from the 6/6 waveform group were cardioverted with a lower mean voltage of 254/92 versus 355/127 V (P < 0.02), at lower pain score 1.8 ± 1.3 versus 4.2 ± 2.2 (P < 0.05) with equivalent energy (6.8 ± 2.8 versus 6.2 ± 1.5 J, n.s.) and required lower doses of midazolam of 2.2 ± 1.9 versus 4.0 ± 1.8 mg IV (P < 0.02). The waveform used in internal cardioversion seems to have a major impact on the patients’ perception of pain. These results imply that energy determines the success of a shock, but voltage determines the pain perceived by the patient. The use of waveforms that deliver greater energy at lower peak voltages offers the possibility of internal cardioversion with less sedation and greater patient tolerance.     

Atrial Ejection Force in Patients with Atrial Fibrillation: Comparison Between DC Shock and Pharmacological Cardioversion

It is well known that the restoration of sinus rhythm is not always associated with the return of effective atrial contraction. Atrial ejection force (AEF) is a noninvasive Doppler derived parameter that measures the strength of the atrial contraction. The aim of the present study was to use pulsed-Doppler echocardiography to determine if different modalities of cardioversion influence the delay in the return of effective atrial contraction after cardioversion. DC shock and pharmacological therapy were compared. Sixty-eight patients were randomly cardioverted, either using DC shock or i.v. procainamide. The patients who were restored to a sinus rhythm had a complete Doppler echocardiographic examination within 1 hour after the restoration, after 24 hours, after 1 month, and after 3 months. AEF was measured and compared in the two groups of patients and within the same group. AEF was greater immediately and at 24 hours after cardioversion in patients who underwent pharmacological therapy compared to patients treated with DC shock (peak A wave, 60 ± 9 vs 31 ± 8 msec, P < 0.001; AEF 11.3 ± 3 vs 5 ± 2.9 dynes, P < 0.001). In both groups, AEF increases over time. In conclusion, AEF is a noninvasive parameter that can be easily measured after cardioversion and can give accurate information about the recovery of left atrial mechanical function. This finding may have important implications for guiding the anticoagulant therapy after cardioversion.     

Internal Cardioversion in Two Patients with Atrial Fibrillation Refractory to External Cardioversion

A-26year-old man underwent an electrophysiological study for evaluation of a history of congenital heart disease, presyncope, and wide complex tachycardia. During the study the patient developed sustained atrial fibrillation with a rapid ventricular response. A 17-year-old man with a history of sick sinus syndrome developed sustained atrial fibrillation. Both patients failed four attempts at external Cardioversion with a maximum delivered energy of 360 J. Low energy Cardioversion was successful in both patients using biphasic waveforms and internal transvenous defibrillation electrodes. Internal Cardioversion using a transvanous electrode system can be successful in patients with atrial fibrillation refractory to external Cardioversion.     

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 ≥ 2.8 seconds (31% vs 11% P = 0.021). The average heart rate was lower in patients with RR‐max ≥ 2.8 seconds, but the average rate was not predictive of AF recurrence. Conclusion: Ventricular pauses during AF predict relapse after ECV. (PACE 2010; 934–938)