A review of clinical trials assessing the efficacy and safety of newer antiarrhythmic drugs in atrial fibrillation

Efficacy and safety in pharmacological cardioversion of recent-onset atrial fibrillation: a propensity score matching to compare amiodarone vs class IC antiarrhythmic drugs

The acute management of recent-onset (<48 h) atrial fibrillation (AF) is still debated. Aim of our study was to compare efficacy and safety of intravenously administered class IC antidysrhythmic agents vs amiodarone in a propensity score matched series of patients acutely treated for AF in the emergency department. During a 3-year period, we retrospectively evaluated all episodes of recent-onset (<48 h) AF pharmacologically treated for sinus rhythm restoration in the emergency department. By means of a propensity score matching considering the main statistically different covariates, we selected two accurately matched treatment groups. We analysed the differences between amiodarone and class IC group in terms of efficacy and safety that is conversion to sinus rhythm rates within 12 and 48 h after starting treatment, time to conversion, and adverse drug effects. An overall number of 817 episodes of recent-onset AF were collected (amiodarone group = 406, class IC group = 411). After matching, we obtained 358 episodes equally divided (amiodarone group = 179 and class IC group = 179). Conversion rates within 12 h were 139 (53.1 %) in amiodarone group and 95 (72.6 %) in class IC group (p < 0.05). Median time for cardioversion was 420 min (331.6-508.3 CI 95 %) in amiodarone and 55 min (44.9-65.1 CI 95 %) in class IC group (p < 0.05). The incidence of adverse events in both groups was very low and equally distributed (p = ns). Intravenously administration of class IC agents, when compared with amiodarone, proved to be more rapid and effective, and equally safe in the acute management of recent-onset AF.

Antiarrhythmic Drug Therapy for Atrial Fibrillation

Atrial fibrillation (AF) is the most frequently encountered arrhythmia. Prevalence increases with advancing age and so as its associated comorbidities, like heart failure. Choice of pharmacologic therapy depends on whether the goal of treatment is maintaining sinus rhythm or tolerating AF with adequate control of ventricular rates. Antiarrhythmic therapy and conversion of AF into sinus rhythm comes with the side effect profile, and we should select best antiarrhythmic therapy, individualized to the patient. New antiarrhythmic drugs are being tested in clinical trials. Drugs that target remodeling and inflammation are being tested for their use as prevention of AF or as upstream therapy.

The HARMONY Trial: Combined Ranolazine and Dronedarone in the Management of Paroxysmal Atrial Fibrillation: Mechanistic and Therapeutic Synergism

BACKGROUND

Atrial fibrillation (AF) requires arrhythmogenic changes in atrial ion channels/receptors and usually altered atrial structure. AF is commonly treated with antiarrhythmic drugs; the most effective block many ion channels/receptors. Modest efficacy, intolerance, and safety concerns limit current antiarrhythmic drugs. We hypothesized that combining agents with multiple anti-AF mechanisms at reduced individual drug doses might produce synergistic efficacy plus better tolerance/safety.

METHODS AND RESULTS

HARMONY tested midrange ranolazine (750 mg BID) combined with 2 reduced dronedarone doses (150 mg BID and 225 mg BID; chosen to reduce dronedarone's negative inotropic effect-see text below) over 12 weeks in 134 patients with paroxysmal AF and implanted pacemakers where AF burden (AFB) could be continuously assessed. Patients were randomized double-blind to placebo, ranolazine alone (750 mg BID), dronedarone alone (225 mg BID), or one of the combinations. Neither placebo nor either drugs alone significantly reduced AFB. Conversely, ranolazine 750 mg BID/dronedarone 225 mg BID reduced AFB by 59% versus placebo (P=0.008), whereas ranolazine 750 mg BID/dronedarone 150 mg BID reduced AFB by 43% (P=0.072). Both combinations were well tolerated.

CONCLUSIONS

HARMONY showed synergistic AFB reduction by moderate dose ranolazine plus reduced dose dronedarone, with good tolerance/safety, in the population enrolled.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov; Unique identifier: NCT01522651.

Long-term prognostic value of dysglycemia and ischemic vascular disease beyond abnormal troponin levels in patients presenting acute atrial fibrillation

BACKGROUND

Prognostication beyond troponin levels in patients with acute atrial fibrillation (AF) is still unclear.

METHODS

One-month and 1-year outcomes in 1091 patients with acute AF were analyzed. Primary endpoints were stroke or the composite of acute coronary syndrome, revascularization, and death.

RESULTS

In the short term, troponin (odds ratio (OR) 15, 95% confidence interval (CI), 3.4-67.9, P < 0.001) and known ischemic heart disease (OR 5.83, 95% CI, 1.3-26.2, P = 0.021) were predictors of the composite endpoint, with multivariate analysis. No variables linked with stroke. In the long term, metabolic syndrome (OR 4.7, 95% CI, 1.2-18.3, P = 0.024) and age (OR 1.1, 95% CI, 1.0-1.1, P = 0.009) were predictors of stroke; metabolic syndrome (OR 4.3, 95% CI, 1.6-11.0, P = 0.003), known ischemic heart disease (OR 3.3, 95% CI, 1.7-6.4, P = 0.001), persistence of AF after the first-line approach (OR 2.2, 95% CI, 1.2-4.3, P = 0.018), and age (OR 1.0, 95% CI, 1.0-1.1, P = 0.025), but not troponin so were of the composite endpoint. In the short term, increased discriminative values in prognostication of the composite endpoint were observed with C-statistic when troponin was compared with dysglycemia (P = 0.032). No variables did better than others in the prognostication of stroke. In the long term, increased discriminative values in the prognostication of stroke were observed with C-statistic when age was compared with troponin (P = 0.020), ischemic heart disease (P = 0.025), and persistence of AF after the first-line approach (P = 0.049); so was for CHADS2 score ≥1 versus vascular disease (P = 0.038).

CONCLUSIONS

In patients with acute AF, abnormal troponin levels add prognostic value to clinical parameters in the short term; dysglycemia and known vascular disease in the long term.

Abnormal troponin level as short-term predictor of poor outcome in acute atrial fibrillation

BACKGROUND

The link between minor troponin (cardiac troponin I [cTnI]) elevations and atrial fibrillation (AF) is still debated.

METHODS

A total of 948 patients with AF lasting less than 48 hours participated in the study and were required to undergo 1-month and 12-month follow-up. The exclusion criteria were represented by younger than 18 years, the presence of hemodynamic instability, or severe comorbidity. Primary end point was the composite of ischemic vascular events inclusive of stroke, acute coronary syndrome, revascularization, and death.

RESULTS

In the short term, 4 patients (5%) of 78 with abnormal cTnI reached the primary end point (P = .001 vs others). Conversely, in the long term, 13 patients (17%) with abnormal cTnI, 21 (10%) with known ischemic vascular disease, and 50 (5%) aged patients (75 ± 10 years) reached the primary end point (P < .001, P < .001, and P = .002, respectively). At multivariate analysis, abnormal cTnI (hazard ratio [HR], 2.84; 95% confidence interval, 1.38-5.84; P = .005), known ischemic vascular disease (HR, 2.03; 95% confidence interval, 1.11-3.70; P = .021), and age (HR, 1.05; 95 confidence interval, 1.02-1.08; P = .002) were predictors of the primary end point. Minimal or minor cTnI elevation (<0.45 or ≥ 0.45 ng/mL, respectively) showed no differences when associated with the primary end point. The C-statistic demonstrated the significant prognostic value of older age and known ischemic vascular disease, beyond troponin. Clinical parameters inclusive of heart rate, blood pressure, and risk factors for arteriosclerosis showed no relationship with adverse events. Readmission rate did not differ between groups.

CONCLUSIONS

In patients with acute AF, minor cTnI elevations link to short-term adverse events. Known ischemic vascular disease and older age showed prognostic value only in the long term.

Aggressive approach and outcome in patients presenting atrial fibrillation and hypertension

AIM

Aggressive approach in patients presenting atrial fibrillation (AF) and hypertension could result in improving rhythm control and reducing admission.

METHODS

Out of 3475 patients presenting AF, those with hypertension (n=1739, 52%) underwent standard (n=591, group 1, years 2004-2005) or aggressive pharmacological and electrical approach (n=1148, group 2, years 2006-2009). Overall, in 1071 patients AF duration was less than 48 h. Primary endpoint was rhythm conversion; secondary endpoints were modalities of rhythm conversion and reduction of admissions.

RESULTS

At univariate and multivariate analyses, AF lasting less than 48 h, absence of comorbidities and younger age were independent predictors of sinus rhythm; conversely, lack of sinus rhythm, older age, AF lasting more than 48 h and comorbidities were independent predictors of hospitalization. Overall, 55% of patients achieved sinus rhythm in group 1 versus 62% in group 2 (p=0.018). Interestingly, in patients with AF lasting less than 48 h, 89% achieved sinus rhythm, more likely by class 1C than by class III antiarrhythmic drugs (p<0.001). Overall reduction of admission accounts for 60%; 50% of patients need admission in group 1 versus 29% in group 2 (p<0.001).

CONCLUSIONS

Aggressive pharmacological and electrical approach in patients presenting AF and hypertension significantly improved rhythm conversion overall up to 62%. Patients with AF lasting less than 48 h eventually achieved sinus rhythm up to 89%, mostly by class IC antiarrhythmic drugs. Admissions eventually reduced up to 60%.

A case of flecainide-induced hyponatremia

We present a case of flecainide-induced hyponatremia in a 67-year-old woman who was treated for paroxysmal atrial tachycardia. She developed dizziness after starting flecainide and was found to be hyponatremic with a sodium level of 122 mmol/L (decreased from 136 mmol/L). Work-up failed to reveal other causes of hyponatremia. She was not on diuretics, laxatives, or herbal medications. After discontinuation of flecainide, her symptoms and sodium levels improved. Hyponatremia is a previously unrecognized entity as an adverse effect of flecainide. We will discuss the clinical presentation, lab findings, and a possible explanation for this patient's unusual reaction to flecainide.

The Drug And Pace Health cliNical Evaluation (DAPHNE) study: a randomized trial comparing sotalol versus beta-blockers to treat symptomatic atrial fibrillation in patients with brady-tachycardia syndrome implanted with an antitachycardia pacemaker

BACKGROUND

Atrial tachyarrhythmias (ATAs) are mainly treated by pharmacologic therapy for rate control or rhythm control. The aim of our study was to compare sotalol (S) versus beta-blocking agents (BB) in terms of prevention of ATA, cardioversions (CVs), and cardiovascular hospitalizations (H) in patients paced for bradycardia-tachycardia form of sinus node disease (BT-SND).

METHODS

One hundred thirty-five patients (67 males, aged 73 +/- 7 years) were enrolled in a prospective, parallel, randomized, single-blind, multicenter study. All patients received a dual chamber rate adaptive pacemaker; after 1 month, 66 patients were randomly assigned to BB (62 +/- 26 and 104 +/- 47 mg/d for atenolol and metoprolol, respectively) and 69 patients to S (167 +/- 66 mg/d).

RESULTS

After an observation period of 12 months, the percentage of patients free from ATA recurrences was 29% in both BB and S group. Cardioversion and H were significantly (P < .01) fewer in the 12 months after implantation than in the 12 months before both in patients treated with S (CV 69.4% vs 22.2%, H 91.7% vs 33.3%) and in patients treated with BB (CV 58.5% vs 17.1%, H 82.9% vs 26.8%). Kaplan-Meier survival analysis showed a nonsignificant trend toward a lower incidence of the composite end point (CV + H) among BB patients.

CONCLUSIONS

In the complex context of "hybrid therapy" in patients with BT-SND implanted with a modern dual chamber rate adaptive pacemaker device delivering atrial antitachycardia pacing, no differences were found between the use of beta-blocker and the use of S, at the relatively low dose achieved after clinical titration, in terms of prevention of cardiovascular H or need for atrial CV.

Drug therapy for atrial fibrillation

Atrial fibrillation (AF) is the most frequently diagnosed arrhythmia. Prevalence increases with age, and the overall incidence is expected to increase as the population continues to age. Choice of pharmacologic therapy for atrial fibrillation depends on whether or not the goal of treatment is maintaining sinus rhythm or tolerating atrial fibrillation with adequate control of ventricular rates. New antiarrhythmic drugs are being tested in clinical trials. Drugs that target remodeling and inflammation are being tested for their use as prevention of AF or as adjunctive therapy.

Reduced incidence of vagally induced atrial fibrillation and expression levels of connexins by n-3 polyunsaturated fatty acids in dogs

OBJECTIVES

This open-label canine study assessed whether n-3 polyunsaturated fatty acids (PUFAs) prevent vagally induced atrial fibrillation (AF) and influence atrial tissue expression levels of connexins (CXs).

BACKGROUND

n-3 polyunsaturated fatty acids in fish oils protect against sudden cardiac death and reduce postoperative AF. Changes in spatial organization of gap junctions or cellular CX levels have been linked to arrhythmogenesis.

METHODS

Vagally induced AF was studied. Eight dogs were given fish oil daily for 14 days. Eight control dogs had reproducibly induced AF and were re-evaluated after intravenous administration of fish oil. Atrial fibrillation was compared, and n-3 PUFA, CX40, and CX43 protein levels were assessed in atrial biopsies.

RESULTS

Atrial tissue n-3 PUFA levels increased in oral treatment dogs (5.78 +/- 0.71% vs. 2.49 +/- 0.46% in control animals, p < 0.001). No difference was observed for atrial refractory periods or hemodynamic or electrocardiographic parameters. Incidence of AF in oral treatment dogs decreased 79% with the extra stimulus technique (10.5% vs. 48.9%, p = 0.003) and 42% with burst induction (22.5% vs. 38.8%, p = 0.038). Both CX40 and CX43 levels were lower in oral treatment dogs (60% [p = 0.019] and 42% [p = 0.038] lower, respectively); protection against AF was mostly related to reduced CX40 expression levels (p = 0.02). In dogs that were given intravenous n-3 PUFAs, AF inducibility by the extra stimulus technique was reduced from 75.0% to 28.6% (p = 0.002).

CONCLUSIONS

Oral treatment with fish oils increased atrial n-3 PUFA levels and reduced vulnerability to induction of AF in this dog model. Modulation of cardiac CX by n-3 PUFAs probably contributes to the antiarrhythmic effects of fish oils.

Electrical cardioversion for persistent atrial fibrillation or atrial flutter in clinical practice: predictors of long-term outcome

Despite the results of Atrial Fibrillation Follow-up Investigation of Rhythm Management and Rate Control versus Electrical Cardioversion for Persistent Atrial Fibrillation trials, which favour a general shift in atrial fibrillation (AF) therapeutic approach towards control of ventricular rate, a strategy based on restoration of sinus rhythm could still play a role in selected patients at lower risk of AF recurrence. We explored possible predictors of relapses after external electrical cardioversion among patients with persistent AF or atrial flutter (AFL). We analysed the clinical characteristics and conventional echocardiographic parameters of patients with persistent AF/AFL enrolled in an institutional electrical cardioversion programme. Among 242 patients (AF/AFL, 195/47; mean age 62+/-13 years), sinus rhythm was restored in 215 (89%) and maintained in 73 (34%) at a follow-up of 930 days (median). No baseline clinical/echocardiographic variables predicted acute efficacy of cardioversion at logistic regression analysis. However, two variables predicted long-term AF/AFL recurrence among patients with successful cardioversion at multivariate Cox's proportional hazards analysis: (i) duration of arrhythmia>or=1 year (HR, 2.07; 95% CI, 1.29-3.33) and (ii) presence of previous cardioversion (HR, 1.67; 95% CI, 1.17-2.38). These variables also presented high-positive predictive values (72% and 80% respectively). Whereas the high acute efficacy of electrical cardioversion (approximately 90%) does not appear to be predictable, two simple clinical variables could help identify patients at higher risk of long-term AF/AFL recurrence after successful electrical cardioversion. We think there could be a case for initially attempting external electrical cardioversion to patients who have had AF/AFL for <1 year. In such patients, the chance of long-term success appears to be relatively high.

Treating atrial fibrillation. What is the consensus now?

Atrial fibrillation (AF) is a common cardiac arrhythmia, especially in elderly persons. Current recommendations outline pharmacologic and interventional therapies designed to minimize the risk of stroke and other morbidities that can accompany this condition. In this article, Drs Basu Ray and Heist review treatment options for cardioversion and control of rate and rhythm and make suggestions for best management in patients with chronic or intermittent AF.

Selection of drugs in pursuit of rate control strategy

Atrial fibrillation is the most common sustained arrhythmia. Based on multiple large randomized trials, rate control therapy has been shown to be safe and effective and is gaining greater acceptance as a frontline alternative to drugs to maintain sinus rhythm. Adequate rate control can be achieved by atrioventricular nodal blocking agents both in the acute and chronic settings. In refractory patients, other methods such as atrioventricular node ablation can be used to control rate.

Ibutilide – recent molecular insights and accumulating evidence for use in atrial flutter and fibrillation

Ibutilide is a 'pure' class III antiarrhythmic drug, used intravenously against atrial flutter and fibrillation. At a cellular level it exerts two main actions: induction of a persistent Na+ current sensitive to dihydropyridine Ca2+ channel blockers and potent inhibition of the cardiac rapid delayed rectifier K+ current, by binding within the channel pore cavity upon channel gating. Ibutilide has been shown to terminate atrial flutter and fibrillation in animal studies, with some risk of ventricular pro-arrhythmia. Experimental models of hypertrophy/heart failure show altered sensitivity to ibutilide, with increased dispersion of repolarisation and incidence of pro-arrhythmia. Patient trials show that ibutilide is effective at terminating atrial arrhythmias when given alone, and that it can increase effectiveness and reduce energy requirements of electrical cardioversion. The risk to patients of polymorphic ventricular tachycardia necessitates careful patient selection and monitoring during and after treatment. An ibutilide analogue, trecetilide, requires further investigation but may offer a less readily metabolised and pro-arrhythmic alternative to ibutilide.