Efficacy of biphasic waveform cardioversion for atrial fibrillation and atrial flutter compared with conventional monophasic waveforms

Acute anticoagulation adjustment in patients with atrial fibrillation at risk for stroke: approaches, strategies, risks and benefits

The acute management of anticoagulation in patients with atrial fibrillation to prevent stroke and other thromboembolic complications includes the use of individualized strategies tailored to the patient and based on the situation (cardioversion, surgeries, dental procedures, cardiac interventions, other invasive procedures and initiation of, or adjustment to, warfarin dosing). The vast range of choices can cause confusion and few randomized controlled clinical trials in this area provide adequate guidance. Chronic anticoagulation management is more straightforward since clinical evidence is ample, randomized clinical trial data provides cogent informaiton and guidelines have been established. Acute management of anticoagulation in patients with atrial fibrillation to prevent thromboembolic complications is often unrecognized but is emerging as a crucial, but challenging, and increasingly complex aspect of the care of patients with atrial fibrillation. This review addresses issues regarding such patients who may be at risk for stroke and require acute adjustments of anticoagulation (in light of, or in lieu of, chronic anticoagulation). Several promising new strategies are considered in light of established medical care. This analysis provides practical recommendations based on available data and presents results from recent investigations that may provide insight into future strategies.

Is pretreatment with ibutilide useful for atrial fibrillation cardioversion when combined with biphasic shock?

OBJECTIVE

Cardioversion of atrial fibrillation by means of a monophasic transthoracic shock is facilitated by pretreatment with ibutilide. The aim of this study was to randomly and prospectively compare the energy requirements of transthoracic biphasic cardioversion of atrial fibrillation with and without ibutilide pretreatment.

METHODS

Fifty patients were enrolled and randomized into two groups: immediate cardioversion with biphasic shock (group 1) or ibutilide pretreatment followed by cardioversion with biphasic shock (group 2). In group 2, ibutilide was administered intravenously in 10 min at a dose of 0.01 mg/kg. A pause of 10 min was observed before the patients underwent cardioversion.

RESULTS

All patients of both groups were successfully cardioverted (100%). Energy and number of shocks were significantly lower in group 2 than in group 1 (P< 0.02). Eleven of 25 patients (44%) in group 1 and 15 of 23 patients (65%) in group 2 were cardioverted at the first attempt with 50 J. The number of patients cardioverted at the first attempt with 50 J was significantly higher in group 2 than in group 1 (P = 0.018).

CONCLUSIONS

Although not essential for a successful outcome, pretreatment with ibutilide can lower energy requirements in transthoracic biphasic cardioversion.

Efficacy of biphasic waveform compared to monophasic waveform for cardioversion of atrial flutter in pediatric patients

The efficacy of biphasic waveform cardioversion of atrial flutter in pediatric patients has not previously been demonstrated. Cardioversion outcomes were compared in two sequential groups of patients with atrial flutter undergoing transthoracic cardioversion using monophasic and biphasic waveforms at a single pediatric institution. The mean energy required for procedural success was 1.7 +/- 1.2 J/kg in the monophasic group compared to 0.9 +/- 0.6 J/kg in the biphasic group (p = 0.002). The mean number of attempts before achieving procedural success was 1.9 +/- 1.2 for the monophasic group and 1.3 +/- 1.0 for the biphasic group (p = 0.019). Procedure success rate was 89.5% (33/38) in the monophasic group compared to 100% (27/27) in the biphasic group (p = 0.13). Success rate for biphasic waveform cardioversion was 83% (5/6) when using energy less than 0.5 J/kg. These findings provide the impetus for lower starting energies and more widespread use of devices utilizing biphasic waveforms in pediatric patients.

A trial of self-adhesive patch electrodes and hand-held paddle electrodes for external cardioversion of atrial fibrillation (MOBIPAPA)

AIMS

External electrical cardioversion is the method of choice to terminate persistent atrial fibrillation. Whether the type of shock electrode affects cardioversion success is not known. We tested whether hand-held steel electrodes improve cardioversion outcome with monophasic or biphasic shocks when compared with adhesive patch electrodes.

METHODS AND RESULTS

Two hundred and one consecutive patients with persistent atrial fibrillation (147 male, mean age 63+/-1 years, duration of atrial fibrillation 6.3+/-1 months) were randomly assigned to cardioversion using either a sinusoidal monophasic or a truncated exponential biphasic shock wave form. The first half of patients were cardioverted using adhesive patch electrodes, the second half using hand-held steel paddle electrodes, and all patients using an anterior-posterior electrode position. Paddle electrodes successfully cardioverted 100/104 patients (96%) and patch electrodes 85/97 patients (88%, P=0.04). This effect was comparable to that of biphasic shocks: biphasic shocks cardioverted 102/104 patients (98%) and monophasic shocks 83/97 patients (86%, P=0.001). A beneficial effect of paddle electrodes was observed for both shock wave forms. After cross-over from an ineffective monophasic to a biphasic shock, cardioversion was successful in 198/201 (98.5%) patients. Unsuccessful cardioversion after cross-over (3/201 patients) only occurred with patch electrodes (P=0.07).

CONCLUSION

Hand-held paddle electrodes increase success of external cardioversion of atrial fibrillation in this trial. This increase is of similar magnitude as the increase in cardioversion success achieved with biphasic shocks. A combination of biphasic shocks, paddle electrodes, and an anterior-posterior electrode position renders outcome of external cardioversion almost always successful (104/104 patients in this trial).

Overview of the management of atrial fibrillation: what is the current state of the art?

Management of Atrial Fibrillation. There are three fundamental approaches to the management of atrial fibrillation (AF): rate control, rhythm control, and anticoagulation. Selecting a course of treatment requires a thorough knowledge of these therapeutic alternatives. This article explores treatment options, including the relative benefits of rate control versus rhythm control, which are complicated by the lack of highly effective and safe antiarrhythmic drugs. Anticoagulation is also an important issue in AF management, and warfarin effectively reduces the incidence of thromboembolic events in AF patients. The use of warfarin, however, presents its own complications. We conclude that individualization of therapy is paramount when treating AF.