Late thromboembolic events after circumferential pulmonary vein ablation of atrial fibrillation

Background  

Catheter ablation can restore sinus rhythm in selected patients with atrial fibrillation (AF), but its preventive function for thromboembolic events (TE) is still underdetermined.     

Intermittent interatrial block after electrical cardioversion for atrial fibrillation

A 67-year-old woman with persistent atrial fibrillation presented for elective electrical cardioversion. The patient was cardioverted to normal sinus rhythm with a synchronized 150 joules (J) biphasic shock. Varying P-wave morphology suggesting intermittent interatrial block (IAB) was noted after the cardioversion on the rhythm strip. Three minutes later the patient developed early recurrence of atrial fibrillation and a second successful 150 J biphasic shock was delivered; IAB was still evident on a single lead II monitoring. However, the patient remained in sinus rhythm. The patient was discharged in normal sinus rhythm with electrocardiographic evidence of intermittent interatrial block. This case report examines the occurrence of IAB postcardioversion for atrial fibrillation and speculates on its prognostic significance.     

Anticoagulation for cardioversion of atrial fibrillation

The cardioversion of chronic atrial fibrillation to sinus rhythm carries a thromboembolic risk of 1.5-6%. These events occasionally occur at the time of cardioversion, but more often happen hours or days later. These strokes and other embolic events may occur even where atrial thrombus has been excluded before cardioversion and it has become apparent that, although atrial electrical activity may be restored by cardioversion, normal mechanical atrial function may take longer to recover. Numerous studies have addressed the role of anticoagulation following cardioversion in patients with atrial fibrillation, however, the mechanism of embolic complications as well as the justification of a standard anticoagulation therapy are not fully established. In this review we will try to present an overview of the mechanisms of thrombosis following cardioversion and give an insight into current anticoagulation strategies.     

Factors predicting recurrence of atrial fibrillation after cardioversion

BACKGROUND: Factors predicting the maintenance of sinus rhythm (SR) after cardioversion of atrial fibrillation (AF) have not been well defined. Little is known about the impact of the recovery of the left atrial mechanical function (RLAMF) on AF recurrences. AIM: To identify the clinical and echocardiographic predictors of AF recurrences after cardioversion. METHODS: Of 112 consecutive patients (39 females, 73 males, mean age 62.1+/-10.6 years) with AF who underwent successful electrical or pharmacological cardioversion, 50 maintained SR during 6 month follow-up whereas the remaining 62 had a recurrence of AF. Clinical examination and 2D Doppler echocardiography were performed. From the Doppler mitral flow, RLAMF was evaluated 1, 7, and 21 days after cardioversion. RESULTS: Patients with or without AF recurrence did not differ with respect to age, gender, aetiology, duration of AF, LA size and ejection fraction. In the univariate analysis the lack of RLAMF detected 1 day after cardioversion (relative risk - RR=1.15, p<0.01), functional NYHA class II or III (RR=1.86, p<0.005) and a history of AF episodes (RR=2.02, p相似文献   

Detection of myocardial injury after internal cardioversion for atrial fibrillation

BACKGROUND: Cardiac troponin levels do not rise to marked levels after external cardioversion of atrial fibrillation. Subsequent test discharges during implantation of cardioverter defibrillators may cause an elevation of cardiac troponin levels, but are still controversial. OBJECTIVE: To determine whether the biomarkers of cardiac injury increase after internal cardioversion (IC) of atrial fibrillation. METHODS: Forty-four patients with chronic atrial fibrillation were studied (mean age 59 +/-7 years). Electrode catheters were inserted through the femoral vein. One of these was positioned in the lower right atrium. A second defibrillation electrode was placed in the coronary sinus and an additional catheter was positioned in the right ventricular apex in order to obtain satisfactory R wave synchronization and to provide postshock ventricular pacing. The shocks were delivered by external defibrillator. Starting with a test shock of 1 J intensity, the energy was increased in steps (to maximum 15 J) until cardioversion was achieved. At least 1 min was permitted to elapse between unsuccessful defibrillation attempts before the next shock was applied. Blood samples for serum levels of cardiac troponin T, cardiac troponin I, creatine kinase MB and myoglobin were drawn before and 2 h, 4 h, 8 h and 24 h after IC. Each level of biomarker was compared with baseline. RESULTS: In 40 of 44 patients, IC was successful at a mean cardioversion threshold of 7.6+/-3.3 J. Although the serum levels of these biomarkers tended to rise, marked elevation was not detected in any of samples (P>0.05 for each). There was no correlation between the levels of biomarkers and the number and energy of shocks applied. No severe complications were observed. CONCLUSIONS: Following uncomplicated IC of atrial fibrillation, cardiac biomarkers do not rise to marked levels, which indicates that significant myocardial injury does not occur by shocks in the usual dosage.     

D-dimer level influences thromboembolic events in patients with atrial fibrillation

BACKGROUND: Elevated coagulative molecular markers could reflect the prothrombotic state in the cardiovascular system of patients with non-valvular atrial fibrillation (NVAF). A prospective, cooperative study was conducted to determine whether levels of coagulative markers alone or in combination with clinical risk factors could predict subsequent thromboembolic events in patients with NVAF. METHODS: Coagulative markers of prothrombin fragment 1+2, D-dimer, platelet factor 4, and beta-thromboglobulin were determined at the enrollment in the prospective study. RESULTS: Of 509 patients with NVAF (mean age, 66.6 +/- 10.3 years), 263 patients were treated with warfarin (mean international normalized ratio, 1.86), and 163 patients, with antiplatelet drugs. During an average follow-up period of 2.0 years, 31 thromboembolic events occurred. Event-free survival was significantly better in patients with D-dimer level < 150 ng/ml than in those with D-dimer level>or==150 ng/ml. Other coagulative markers, however, did not predict thromboembolic events. Age (>or==75 years), cardiomyopathies, and prior stroke or transient ischemic attack were independent, clinical risk factors for thromboembolism. Thromboembolic risk in patients without the clinical risk factors was quite low (0.7%/year) when D-dimer was < 150 ng/ml, but not low (3.8%/year) when D-dimer was >or==150 ng/ml. It was >5%/year in patients with the risk factors regardless of D-dimer levels. This was also true when analyses were confined to patients treated with warfarin. CONCLUSIONS: D-dimer level in combination with clinical risk factors could effectively predict subsequent thromboembolic events in patients with NVAF even when treated with warfarin.     

Atrial fibrillation and thromboembolic events prevention. State of the art

Atrial Fibrillation (AF) is a common cardiac arrhythmia and stroke is its most devasting complication. The rate of ischemic stroke among people with AF is approximately six times that of people without AF and varies importantely with coexistent cardiovascular diseases; therefore stratification of AF patients into those at high and low risk of thromboembolism has become a crucial determinant of optimal antithrombotic prophylaxis. Multivaria-te analyses of prospective studies consistently show prior TIA/stroke, diabetes, age, heart failure to be independently predictive of stroke; left ventricular dysfunction is also strongly associated with stroke risk. Several randomized clinical trials demonstrated that treatment with adjusted-dose warfarin reduces the risk of stroke in AF patients by about two thirds. The efficacy of aspirin for prevention of stroke is controversial, but supported by pooled results of 3 placebo-controlled trials yelding a 21% reduction in stroke. The inherent risk of stroke should be considered in selection of AF patients for lifelong anticoagulation. Patients with AF and a recent stroke or TIA or multiple risk factors for stroke are likely to benefit from anticoagulation therapy; at present a target INR 2,5 appears optimal for most patients, although INR closer to 2.0 may be safer for patients at increased risk for bleeding events. The addition of aspirin to low- dose warfarin regimen does not provide any significant benefits and should be avoided. Therapy with aspirin is appropriate for patients who are at low risk of stroke or are unable to receive anticoagulants. AF patients treated with aspirin, should be periodically evaluated for development of high-risk features favoring anticoagulation.     

Amiodarone after unsuccessful direct-current cardioversion of persistent atrial fibrillation

AIM: To assess the safety and efficacy of amiodarone used after unsuccessful direct current (DC) cardioversion of persistent atrial fibrillation (AF). METHODS: The study group comprised 67 patients (F/M 26/41; mean age 61.3+/-11.2 years) after unsuccessful DC cardioversion (DCC) of persistent AF (mean arrhythmia duration 212.6+/-135.2 days) in whom another attempt of DCC was intended. Repeat DC cardioversion was performed after loading with oral amiodarone, for a period necessary to achieve a cumulative dose of up to 12.0-16.0 g. Pretreatment was an outpatient procedure. After successful DC cardioversion all study subjects received a maintenance dose of amiodarone, 100-200 mg daily, aimed at preventing AF. The follow-up period was 12 months. RESULTS: Spontaneous conversion to sinus rhythm (SR) during amiodarone pretreatment was observed in 13 pts (19.2%). DCC was performed in 54 pts and SR was restored in 41 of the study pts (76%). Complications occurred in 3 pts, including 1 case of apparent hyperthyroidism and 2 cases of decreased TSH level, and required amiodarone withdrawal. After 12 months, 72.2% of pts maintained SR on low dose (179.2+/-42.1 mg/day) amiodarone. Spontaneous conversion to SR during amiodarone loading was significantly related to long-term SR maintenance after successful DC cardioversion (p<0.013; RR 2.01; 95% CI 1.34-3.03). CONCLUSION: Pretreatment with amiodarone and repeat DC cardioversion results in sinus rhythm restoration in about 80.6% of pts with persistent AF after an initial unsuccessful attempt. Direct-current cardioversion can be performed safely taking standard precautions for patients receiving amiodarone. At 12 months after successful repeated DC cardioversion, more than 72.2% of pts on low-dose amiodarone maintain SR.     

Exaggerated QT prolongation after cardioversion of atrial fibrillation.

OBJECTIVES: The purpose of this study was to test the hypothesis that the extent of drug-induced QT prolongation by dofetilide is greater in sinus rhythm (SR) after cardioversion compared with during atrial fibrillation (AF). BACKGROUND: Anecdotes suggest that when action potential-prolonging antiarrhythmic drugs are used for AF, excessive QT prolongation and torsades de pointes (TdP) often occur shortly after sinus rhythm is restored. METHODS: QT was measured in nine patients with AF who received two identical infusions of dofetilide: 1) before elective direct current cardioversion and 2) within 24 h of restoration of SR. RESULTS: During AF, dofetilide did not prolong QT (baseline: 368 +/- 48 ms vs. drug: 391 +/- 60, p = NS) whereas during SR, QT was prolonged from 405 +/- 55 to 470 +/- 67 ms (p < 0.01). In four patients (group I), the SR dofetilide infusion was terminated early because QT prolonged to >500 ms, and one patient developed asymptomatic nonsustained TdP. The remaining five patients (group II) received the entire dose during SR. Although deltaQT was greater in group I during SR (91 +/- 22 vs. 45 +/- 25 ms, p < 0.05), plasma dofetilide concentrations during SR were similar in the two groups (2.72 +/- 0.96 vs. 2.77 +/- 0.25 ng/ml), and in AF (2.76 +/- 1.22 ng/ml). DeltaQT in SR correlated inversely with baseline SR heart rate (r = -0.69, p < 0.05), and QT dispersion developing during the infusion (r = 0.79, p < 0.01). CONCLUSIONS: Shortly after restoration of SR, there was increased sensitivity to QT prolongation by this I(Kr)-specific blocker. Slower heart rates after cardioversion and QT dispersion during treatment appear to be important predictors of this response.     

The optimal technique for electrical cardioversion of atrial fibrillation

The optimal approach to electrical cardioversion of atrial fibrillation includes appropriate patient selection, anticoagulation, careful selection and monitoring of antiarrhythmic therapy, and proper electrical cardioversion technique. The optimal technique requires the use of metal electrodes, with one electrode of at least 8 cm in diameter placed in the anterior position, and the second of 12–13 cm diameter placed posteriorly just below the left scapulae, with generous amounts of the appropriate gel (such as Hewlett-Packard Redux Paste) as the electrode-skin interface and firm pressure to the paddle electrode with the patient in expiration. Thus the anterior-posterior chest diameter is decreased and less air between the electrodes is assured. The initial shock strength should be 200 J. The shock is synchronized with the electrocardiographic QRS complex. This report reviews the justification for these recommendations.