Use of irbesartan to maintain sinus rhythm in patients with long-lasting persistent atrial fibrillation: a prospective and randomized study

Prevention of Atrial Fibrillation With Angiotensin-Converting Enzyme Inhibitors and Angiotensin Receptor Blockers

OBJECTIVES

This study was designed to identify all randomized clinical trial data evaluating angiotensin-converting enzyme inhibitors or angiotensin receptor blockers for the prevention of atrial fibrillation (AF), to estimate the magnitude of this effect and to identify patient subgroups most likely to benefit.

BACKGROUND

Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) reduce morbidity and mortality in patients with heart failure, vascular disease, and hypertension. Several reports suggest that they may also prevent the development of AF.

METHODS

A systematic review of the literature was performed to identify all reports of the effect of ACEIs or ARBs on the development of AF. Eligible studies had to be randomized, controlled, parallel-design human trials of an ACEI or ARB that collected data on the development of AF.

RESULTS

A total of 11 studies, which included 56,308 patients, were identified: 4 in heart failure, 3 in hypertension, 2 in patients following cardioversion for AF, and 2 in patients following myocardial infarction. Overall, ACEIs and ARBs reduced the relative risk of AF by 28% (95% confidence interval [CI] 15% to 40%, p = 0.0002). Reduction in AF was similar between the two classes of drugs (ACEI: 28%, p = 0.01; ARB: 29%, p = 0.00002) and was greatest in patients with heart failure (relative risk reduction [RRR] = 44%, p = 0.007). Overall, there was no significant reduction in AF in patients with hypertension (RRR = 12%, p = 0.4), although one trial found a significant 29% reduction in patients with left ventricular (LV) hypertrophy. In patients following cardioversion, there appears to be a large effect (48% RRR), but the confidence limits are wide (95% CI 21% to 65%).

CONCLUSIONS

Both ACEIs and ARBs appear to be effective in the prevention of AF. This benefit appears to be limited to patients with systolic left ventricular dysfunction or LV hypertrophy. The use of these drugs following cardioversion appears promising but requires further study.

C reactive protein concentration and recurrence of atrial fibrillation after electrical cardioversion

BACKGROUND

To test the hypothesis that a high C reactive protein (CRP) concentration would predict recurrence of atrial fibrillation (AF) after cardioversion in patients taking antiarrhythmic drugs.

METHODS

111 patients who underwent direct current cardioversion for symptomatic AF were enrolled. Blood was drawn for CRP determination before cardioversion on the same day. All patients were taking antiarrhythmic drugs before and after electrical cardioversion.

RESULTS

After a mean follow up of 76 days, 75 patients had recurrence of AF. In univariate analysis, the median CRP concentration was significantly higher in patients with AF recurrence (3.95 mg/l v 1.81 mg/l, p = 0.002). Among the 55 patients with CRP in the upper 50th centile, 44 (80%) experienced recurrence of AF over a total follow up of 8.98 patient years, whereas among the 56 patients with CRP in the lower 50th centile, 31 (55%) experienced recurrence of AF over a total follow up of 14.3 patient years (p < 0.001). The adjusted hazard ratio comparing the upper 50th centile of CRP with the lower 50th centile of CRP was 2.0 (95% confidence interval 1.2 to 3.2, p = 0.007).

CONCLUSIONS

CRP is independently associated with recurrence of AF after electrical cardioversion among patients taking antiarrhythmic drugs. These results suggest that inflammation may have a role in the pathogenesis of AF resistant to antiarrhythmic drugs.

Angiotensin II, angiotensin II antagonists and spironolactone and their modulation of cardiac repolarization

Angiotensin II and aldosterone produce pro-arrhythmic effects by several mechanisms, including the modulation of voltage-dependent K(+) channels involved in human cardiac repolarization. Drugs that inhibit the renin-angiotensin-aldosterone system exert anti-arrhythmic actions that are related to the blockade of the pro-arrhythmic actions of angiotensin II and aldosterone. These anti-arrhythmic actions include inhibition of electrical and structural cardiac remodeling, inhibition of neurohumoral activation, reduction of blood pressure and stabilization of electrolyte disturbances. In this article, several angiotensin II AT(1) receptor antagonists (candesartan, E3174, eprosartan, irbesartan and losartan) and aldosterone receptor antagonists (canrenoic acid and spironolactone) that directly modulate the activity of the voltage-dependent K(+) channels are reviewed; the effects of these antagonists might be useful in the prevention and treatment of cardiac arrhythmias.

Managing the patient at risk for a second stroke

Cerebrovascular disease is a major cause of mortality world-wide, and the prevalence is expected to increase as a result of projected demographic trends. Aggressive antihypertensive therapy is one intervention that has proven highly effective in reducing the risk of stroke, with relatively small blood pressure reductions affording measurable benefit even in patients not conventionally considered hypertensive. Comparative clinical trials are revealing evidence of differential impacts of antihypertensive classes on the incidence of cerebrovascular disease that will probably be important for therapeutic choice in patients with risk factors for stroke. In particular, the role of the renin-angiotensin system in cerebrovascular disease has come under scrutiny as a result of evidence that angiotensin II receptor blockers (ARBs), but perhaps not angiotensin converting enzyme inhibitors, can reduce the risk of a first stroke to a greater degree than might be expected from their effects on blood pressure alone. Although preclinical evidence suggests that there are differential effects of the type 1 and type 2 receptor activation, the clinical relevance of this is not yet known. Furthermore, the effect on the incidence of stroke conferred by blood pressure control in the early morning hours - the time when the incidence of strokes peaks--has not been tested. Some evidence for the beneficial effect of an ARB on secondary stroke prevention comes from the MOrbidity and mortality after Stroke --Eprosartan compared with nitrendipine in Secondary prevention study (MOSES), which showed that the ARB protected against cerebro- and cardiovascular events in hypertensive patients with a previous stroke over and above the protection offered by blood pressure control. These hypotheses are among those being examined in two current large-scale trials: the Prevention Regimen For Effectively avoiding Second Strokes (PRoFESS), and The ONgoing Telmisartan Alone and in combination with Ramipril Global Endpoint Trial (ONTARGET) Trial Programme.

[Molecular biology of the heart atrium. New insights into the pathophysiology of atrial fibrillation as well as its clinical implications]

Atrial fibrillation (AF) is the most common clinical arrhythmia and one of the most important factors for embolic stroke. In recent years, a tremendous amount has been learned about the pathophysiology and molecular biology of AF. Thus, pharmacologic interference with specific signal transduction pathways appears promising as a novel antiarrhythmic approach to maintain sinus rhythm and to prevent atrial clot formation. This review highlights the underlying molecular biology of atrial fibrillation, which may also be relevant for AF therapy.

Angiotensin II receptor blockade reduces new-onset atrial fibrillation and subsequent stroke compared to atenolol

OBJECTIVES

This study was designed to evaluate whether different antihypertensive treatment regimens with similar blood pressure reduction have different effects on new-onset atrial fibrillation (AF).

BACKGROUND

It is unknown whether angiotensin II receptor blockade is better than beta-blockade in preventing new-onset AF.

METHODS

In the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study 9,193 hypertensive patients and patients with electrocardiogram-documented left ventricular hypertrophy were randomized to once-daily losartan- or atenolol-based antihypertensive therapy. Electrocardiograms were Minnesota coded centrally, and 8,851 patients without AF by electrocardiogram or history, who were thus at risk of developing AF, were followed for 4.8 +/- 1.0 years.

RESULTS

New-onset AF occurred in 150 patients randomized to losartan versus 221 to atenolol (6.8 vs. 10.1 per 1,000 person-years; relative risk 0.67, 95% confidence interval [CI] 0.55 to 0.83, p < 0.001) despite similar blood pressure reduction. Patients receiving losartan tended to stay in sinus rhythm longer (1,809 +/- 225 vs. 1,709 +/- 254 days from baseline, p = 0.057) than those receiving atenolol. Moreover, patients with new-onset AF had two-, three- and fivefold increased rates, respectively, of cardiovascular events, stroke, and hospitalization for heart failure. There were fewer composite end points (n = 31 vs. 51, hazard ratio = 0.60, 95% CI 0.38 to 0.94, p = 0.03) and strokes (n = 19 vs. 38, hazard ratio = 0.49, 95% CI 0.29 to 0.86, p = 0.01) in patients who developed new-onset AF in the losartan compared to the atenolol treatment arm of the study. Furthermore, Cox regression analysis showed that losartan (21% risk reduction) and new-onset AF both independently predicted stroke even when adjusting for traditional risk factors.

CONCLUSIONS

Our novel finding is that new-onset AF and associated stroke were significantly reduced by losartan- compared to atenolol-based antihypertensive treatment with similar blood pressure reduction.

Management of atrial fibrillation in patients with congestive heart failure

An increase in the prevalence of both atrial fibrillation and congestive heart failure is occurring in part because of the demographic shift toward an aging population. These two clinical entities often coexist in the same patient, resulting in the worsening of symptoms and prognosis, rendering their management even more challenging. A large clinical trial is currently examining whether a rhythm-control strategy is superior to a rate-control strategy in patients with congestive heart failure. New nonpharmacologic therapies such as pulmonary vein isolation are undergoing clinical investigation and may also alter the management of these patients. At present, therapy for atrial fibrillation in patients with congestive heart failure should aim first at controlling heart rate to provide symptomatic relief; then sinus rhythm should be restored if symptoms persist or if congestive heart failure worsens. For a more definitive approach in managing these patients, the authors await further clinical trial data.

Valsartan reduces the incidence of atrial fibrillation in patients with heart failure: results from the Valsartan Heart Failure Trial (Val-HeFT)

BACKGROUND

Atrial fibrillation (AF) in heart failure (HF) is generally considered a negative prognostic factor. Recent studies indicate that the incidence of AF might be decreased by renin angiotensin aldosterone system inhibitors. The identification of a treatment to prevent its occurrence is likely to improve patients outcome. The aims of these subanalyses of Val-HeFT were to assess (a) the effects of valsartan in the prevention of AF, (b) the independent predictors of this event, and (c) the prognostic role of AF occurrence.

METHODS AND RESULTS

The occurrence of AF was evaluated based on adverse event reports in the patients with HF enrolled in Val-HeFT. Patients were randomized to valsartan or placebo on top of their prescribed treatments for HF. During the mean 23 months of follow-up, AF was reported in 287/4395 patients (6.53%) in sinus rhythm at baseline, of whom 113/2205 (5.12%) were allocated to valsartan and 174/2190 (7.95%) to placebo (P = .0002). Multivariable analysis showed that brain natriuretic peptide (BNP) levels at baseline above the median value (HR 2.28, 95% CI 1.75-2.98), age over 70 years (HR 1.51, 95% CI 1.17-1.95), male sex (HR 1.53, 95% CI 1.07-2.18), and the valsartan treatment (HR 0.63, 95% CI 0.49-0.81) were independently associated with AF occurrence. Cox multivariable regression analysis showed that occurrence of AF was independently associated with a worse prognosis, with the adjusted hazard risks for all-cause mortality and combined mortality/morbidity of 1.40 (95% CI 1.16-1.58) and 1.38 (95% CI 1.12-1.70), respectively.

CONCLUSIONS

The results of the present study demonstrate that (a) adding valsartan to prescribed therapy for HF significantly reduces the incidence of AF by 37%; (b) BNP level and advanced age were the strongest independent predictors for AF occurrence; and (c) AF occurrence further worsens the outcome in patients with HF.

Antiarrhythmic drugs in atrial fibrillation: an overview of new agents, their mechanisms of action and potential clinical utility

Despite recent advances in our understanding of the mechanism of atrial fibrillation (AF), effective treatment remains difficult in many patients. Pharmacotherapy remains the mainstay of treatment and includes control of ventricular rate as well as restoration and maintenance of sinus rhythm. The currently available antiarrhythmic drugs are particularly effective in converting paroxysmal AF to sinus rhythm and in enhancing the positive effect of electrical cardioversion, but are limited in their efficacy in maintaining sinus rhythm. Moreover, there are limited options in the setting of co-existing ischaemic heart disease, left ventricular dysfunction and structural heart diseases. New drugs added to our clinical armamentarium have been, or are being, developed to combine better efficacy and lack of pro-arrhythmic effects. These developments have gained more interest particularly with the recent debate over rate control versus rhythm control for AF. Although some of these agents are promising, their uptake in clinical practice will not only depend on their efficacy as antiarrhythmic agents but also on their safety in acutely terminating AF and in long-term maintenance of sinus rhythm or rate control in the community.

Prevention of recurrences in patients with lone atrial fibrillation. The dose-dependent effect of angiotensin II receptor blockers

BACKGROUND

Atrial fibrillation (AF) leads to the activation of the renin-angiotensin system (RAS), which seems to play an important role in atrial remodelling. It is not known yet whether RAS blockade may prevent recurrences in patients with lone AF.

METHODS AND RESULTS

Patients with an episode of persistent AF for >7 days, in the absence of cardiac or extracardiac causes and with normal blood pressure values (lone AF), were recruited. Ninety patients were randomised and scheduled for electrical cardioversion. Three groups of patients were compared: Group I was treated with amiodarone 400 mg daily (30 patients), group II was treated with amiodarone 400 mg daily plus irbesartan 150 mg daily (30 patients) and group III with amiodarone 400 mg daily plus irbesartan 300 mg daily (30 patients). The primary endpoint was the time to a first recurrence of AF. The patients were cardioverted and followed. The Kaplan-Meier analysis of time to first recurrence during the follow-up period showed that patients treated with amiodarone 400 mg plus irbesartan 300 mg had a greater probability of remaining free of AF (77% vs. 52% for amiodarone and 65% for amiodarone+irbesartan 150 mg), hazard ratio for a recurrence in group III: 0.47 (95% CI 0.27-0.82; p=0.001).

CONCLUSIONS

The combination of irbesartan plus amiodarone decreased the rate of AF recurrences, with a dose-dependent effect, in lone AF patients.

Pharmacologic Strategies for Prevention of Atrial Fibrillation After Open Heart Surgery

Postoperative atrial fibrillation is a common complication after open heart surgery; it increases morbidity, hospital stay, and costs. In an analysis of 8 large cardiac surgery trials totaling 20,193 patients, the incidence of postoperative atrial fibrillation was estimated to be 26% and ranged from 17% to 35%. We reviewed the results of 52 studies published between 1966 and 2003 that evaluated pharmacologic strategies to prevent postoperative atrial fibrillation in nearly 10,000 patients undergoing open heart operations. Supraventricular tachyarrhythmias, including atrial fibrillation, after open heart operations occurred in 29% of patients who did not receive prophylactic drugs, compared with 12% in patients who received intravenous followed by oral amiodarone, 15% in those given sotalol, 16% in those given oral amiodarone, and 19% in those given beta-blockers. Pharmacologic strategies and regimens aimed at preventing postoperative atrial fibrillation are necessary to optimize the postoperative care of patients undergoing open heart operations. Although no strategy has consistently been shown to be superior to another, the most effective approach to preventing postoperative atrial fibrillation likely involves multiple interventions. In the absence of contraindications, all patients should receive beta-blocker therapy before and after the operation. For patients with 1 or more risk factors for postoperative atrial fibrillation, regimens consisting of either sotalol (beta-blocker with class III antiarrhythmic properties) alone or beta-blockers in combination with amiodarone seem to be the safest, most effective pharmacologic strategies for preventing postoperative atrial fibrillation.

Pretreatment with ACE inhibitors improves acute outcome of electrical cardioversion in patients with persistent atrial fibrillation

BACKGROUND

Persistent atrial fibrillation (AF) is difficult to treat. In the absence of class I or III antiarrhythmic drugs sinus rhythm is maintained in only 30% of patients during the first year after electrical cardioversion (ECV). One of the remodeling processes induced by AF is fibrosis, which relates to inducibility and maintenance of AF. The renin-angiotensin system may play a important role in this. The aim of this study was to investigate the role of angiotensin-converting enzyme (ACE) inhibitor use on efficacy of ECV, and occurrence of subacute recurrences.

METHODS

One hundred-seven consecutive patients with persistent AF underwent ECV. In twenty-eight (26%) patients ACE inhibitors had been started before initiation of the present episode of AF ('pre-treated' patients).

RESULTS

ECV was successful in 96% of patients who were on ACE inhibitors before start of the present episode of AF compared to 80% of the patients not pre-treated (p = 0.04). After 1 month of follow-up 49% of the pre-treated patients and 50% of those not pre-treated with ACE inhibition were still in sinus rhythm (p=ns). Multivariate analysis showed that pre-treatment with ACE inhibitors and a smaller left atrial size were independent predictors of successful ECV (OR = 5.8, C.I. 1.3-26.1, and OR = 5.6, C.I. 1.2-25.3, respectively).

CONCLUSIONS

Pre-treatment with ACE inhibitors may improve acute success of ECV but does not prevent AF recurrences.

Effects of Angiotensin II on the Action Potential Durations of Atrial Myocytes in Hypertensive Rats

Angiotensin II (Ang II) has been reported to indirectly influence atrial electrical activity and to play a critical role in atrial arrhythmias in hypertensive patients. However, it is unclear whether Ang II has direct effects on the electrophysiological activity of the atrium affected by hypertension. We examined the effects of Ang II on the action potentials of atrial myocytes enzymatically isolated from spontaneous hypertensive rats (SHRs). The action potentials were recorded by the perforated patch-clamp technique and the atrial expression of the receptors AT1a and AT2 was measured by radioimmunoassay. Ang II significantly shortened the action potential durations (APDs) of SHRs without changes in the resting membrane potentials (RMPs). Pretreatment with selective AT1a blockers abolished the Ang II-induced reduction of atrial APDs of SHRs; however, a selective AT2 blocker did not, which was consistent with the results of the receptor assay. Pretreatment with phosphatidylinositol 3 (PI3)-kinase inhibitor, phospholipase C inhibitor, or protein kinase C (PKC) inhibitor abolished the Ang II-induced shortening of atrial APDs, but pertussis toxin and protein kinase A (PKA) inhibitor did not. To study the effects of chronic AT1a inhibition on Ang II-induced shortening of atrial APD, SHRs were treated with AT1a blocker for 4 weeks. AT1a blocker abolished the Ang II-induced reduction of atrial APDs of SHRs and also significantly lowered their blood pressure. In conclusion, Ang II shortened atrial APDs of SHRs via AT1a coupled with the Gq-mediated inositol triphosphate (IP3)-PKC pathway. Our findings indicated that Ang II caused atrial arrhythmias in hypertensive patients by shortening the effective refractory period of the atrium.

Angiotensin-Converting Enzyme Inhibitor Therapy Inhibits the Progression From Paroxysmal Atrial Fibrillation to Chronic Atrial Fibrillation

BACKGROUND

Atrial fibrillation is a progressive disease, which in the paroxysmal form (PAF) becomes more frequent and finally becomes chronic (CAF). A retrospective analysis of patients with PAF was conducted to examine the hypothesis that angiotensin-converting enzyme inhibitors (ACEI) will prevent the progression to CAF.

METHODS AND RESULTS

On the basis of their treatment, 95 patients with PAF were divided into 2 groups: 42 patients treated with ACEI for hypertension throughout the period of treatment and follow-up (ACEI group) and 53 patients not given ACEI (non-ACEI group). Cardiac rhythms were assessed either from the medical records or the electrocardiograms recorded every 2-4 weeks at follow-up visits. The mean follow-up time was 8.3+/-3.5 years. There was no significant difference in the use of antiarrhythmic drugs, left atrial diameter or left ventricular ejection fraction between the 2 groups. The Kaplan-Meier curve for the time to occurrence of CAF showed a lower incidence of CAF in the ACEI group and demonstrated that the 5-year probability for persistence of PAF without progression to CAF was 88.3%, but 47.5% in the non-ACEI group.

CONCLUSIONS

These results indicate that ACEI will prevent progression from PAF to CAF.

Prognostic value of 24-hour ambulatory blood pressure measurement for the onset of atrial fibrillation in treated patients with essential hypertension

This study retrospectively determined the prognostic variables of blood pressure by 24-hour ambulatory blood pressure measurement in relation to onset of atrial fibrillation in treated patients who had essential hypertension and analyzed the class effect of antihypertensive management on the nonoccurrence of this supraventricular arrhythmia.

Sotalol reverses remodeled action potential in patients with chronic atrial fibrillation but does not prevent arrhythmia recurrence

INTRODUCTION

Recurrence of atrial fibrillation (AF) may be related to AF-induced electrical remodeling characterized by shortening of the atrial action potential duration (APD) and loss of its rate adaptation. We investigated the effects of pretreatment with oral d,l-sotalol on rate-dependent changes in atrial monophasic action potential (MAP) duration after cardioversion of chronic AF with reference to the efficacy in preventing the arrhythmia recurrence.

METHODS AND RESULTS

MAPs were recorded from the right atrium at six pacing cycle lengths (CLs) from 300 to 750 ms in 19 chronic AF patients after electrical cardioversion; 9 had been pretreated with oral d,l-sotalol (196 +/- 42 mg/day) for 7 days and 10 were untreated. MAP duration at 90% repolarization (MAPD90) in 11 control patients increased progressively with increases in CLs from 209 +/- 19 ms at CL = 300 ms to 264 +/- 28 ms at CL = 750 ms. In AF patients without sotalol, the CL-MAPD relation was shifted downward and flattened at longer CLs; MAPD90 values were 206 +/- 11 ms and 227 +/- 16 ms at CLs of 300 and 750 ms, respectively. MAPD90 values at CLs > or =500 ms in AF were significantly shorter than controls. In AF patients with sotalol, the normal CL-MAPD relation was preserved; MAPD90 increased from 226 +/- 19 ms to 282 +/- 46 ms in the CL range. AF recurred within 2 weeks after cardioversion in 14 of 24 patients pretreated with d,l-sotalol (216 +/- 51 mg/day) despite of continuation of sotalol treatment.

CONCLUSION

Sotalol reverses AF-induced decrease in MAPD adaptation to rate in the atria of chronic AF patients, but this effect does not lead to prevention of AF recurrence.

Atrial fibrillation

Atrial fibrillation (AF) is the most common sustained dysrhythmia in adults. It is ironic, then, that although mechanisms and effective treatments for most other supraventricular tachyarrhythmias have been discovered, AF remains incompletely understood and poorly treated. Nonetheless, our understanding of the pathophysiology of AF has improved in the last half-century, including some groundbreaking observations made in the last 10 years. Indeed, for some patients, the potential for cure now appears to be available. Because no unifying mechanism of AF has been proven, the aim of this review is to describe some of the common and important concepts behind current mechanistic theories of AF and how they contribute to our clinical understanding of AF.

Frequency of elevation of C-reactive protein in atrial fibrillation

Inflammation has been implicated in the pathogenesis of cardiovascular diseases. C-reactive protein (CRP), a marker of systemic inflammation, predicts the risk of coronary events and stroke. Atrial fibrillation (AF) is associated with atrial structural changes that may have an inflammatory basis. We tested the hypothesis that CRP is a risk factor for AF. Subjects were those included in the database registry of the Intermountain Heart Collaborative Study from 1994 to 2001. Patients who had >or=1 electrocardiogram that demonstrated AF formed the disease group (n = 347), and those who had neither electrocardiographic nor clinical evidence for AF comprised the control group (n = 2,449). Logistic regression assessed the quartile (Q) of CRP and 13 other clinical and angiographic predictors of AF. Average age was 63 +/- 12 years, 33% were women, and 61% had advanced coronary artery disease. Patients who had AF were older (by 7 years) and more frequently had a history of heart failure than did controls (41% vs 9%). CRP was higher in patients who had AF than in controls (p <0.001). Q-CRP was a univariable predictor of AF (odds ratio 1.39/Q, 95% confidence interval 1.25 to 1.55, p <0.001). Adjusting for age and heart failure decreased the predictive value of Q-CRP to 1.20/Q (95% confidence 1.07 to 1.34, p = 0.002), whereas further adjustment for 11 other variables had little additional effect (odds ratio 1.19/Q, 95% confidence interval 1.06 to 1.33, p = 0.003). Thus, high levels of CRP independently predicted an increased risk of AF among a large, prospectively studied patient cohort that was assessed angiographically. Increased CRP is a new risk marker for AF propensity, and testing therapies that target inflammation should be considered.

The Role of Angiotensin Receptor Blockers and/or Angiotensin Converting Enzyme Inhibitors in the Prevention of Atrial Fibrillation in Patients with Cardiovascular Diseases:

The inhibition of the renin-angiotensin system has demonstrated both experimental and clinical effects in preventing atrial fibrillation. However, there is still uncertainty about the role of these drugs in clinical practice. The objective of this review has been to assess the effects of angiotensin II type-1 receptor blockers (ARBs) and/or angiotensin converting enzyme inhibitors (ACEIs) for preventing atrial fibrillation. We searched the Cochrane controlled Trials Register (Cochrane Library Issue 4, 2002), MEDLINE (January 1980 to November 2003), EMBASE (January 1980 to November 2003) and reference list of articles. We also contacted manufacturers and researchers in the field.

SELECTION CRITERIA

We conducted a meta-analysis of all randomized controlled clinical trials that compared ARBs and/or ACEIs with either placebo or conventional therapy in patients with either hypertension, heart failure, ischemic heart disease, or diabetes mellitus. The pooled outcome was the development of new onset atrial fibrillation. Two reviewers independently assessed trial quality and extracted data. In some cases, the study authors were contacted for additional information. Seven trials involving a total of 24,849 patients were included (11,328 randomized to active therapy and 13,521 to control). There was a significant statistical difference in the pooled development of atrial fibrillation between the treatment and control group. (OR, 0.57; 95% CI, 0.39 to 0.82); test for overall effect z = 2.98 P = 0.003). Treatment with ACEIs/ARBs markedly reduces the risk of development or recurrence of atrial fibrillation.

Atrial fibrillation after radiofrequency ablation of atrial flutter: preventive effect of angiotensin converting enzyme inhibitors, angiotensin II receptor blockers, and diuretics

OBJECTIVES

To determine risk factors for the development of atrial fibrillation (AF) after atrial flutter (AFL) ablation; and to study the relation between AF development and periprocedural drug use.

METHODS

AFL ablation was performed in 196 patients. The relation between AF occurrence and clinical, echocardiographic, and procedural factors and periprocedural drug use was analysed retrospectively by a Cox proportional hazard method.

RESULTS

After a median follow up of 2.2 years, 114 patients (58%) developed at least one AF episode. Factors associated with AF development were the presence of preprocedural AF, a history of cardioversion, and the number of antiarrhythmic drugs used before the procedure. Use of angiotensin converting enzyme (ACE) inhibitors/angiotensin II receptor blockers and diuretics was significantly associated by univariate and multivariate analyses with less development of AF.

CONCLUSIONS

A high proportion of patients develop AF after AFL ablation. The incidence of AF is related to pre-ablation AF and its persistence. ACE inhibitors/angiotensin II receptor blockers and diuretics seem to protect against AF.

Angiotensin-converting enzyme inhibition in hypertensive patients is associated with a reduction in the occurrence of atrial fibrillation

OBJECTIVE

The objective of this study was to determine the effects of angiotensin-converting enzyme inhibition (ACEI) versus long-acting calcium-channel blockade (CCB) on atrial fibrillation (AF) in patients with hypertension.

BACKGROUND

Atrial fibrillation is the most common significant cardiac arrhythmia, and angiotensin II has been implicated in its pathophysiology.

METHODS

This was a retrospective, longitudinal cohort study from a database of 8 million people in the U.S. Patients age > or =18 years with hypertension were eligible if they filled a prescription for either an ACEI or a CCB between January 1995 and June 1999. The use of all other antihypertensive medications was permitted. Patient chronic disease burden was assessed using a modified Charlson index. Patients were matched on a propensity score generated from a logistic regression model. A survival analysis approach was used to compare the incidence of AF between groups. The final cohorts were evaluated until June 2002, and the average follow-up was 4.5 years.

RESULTS

After cohort matching, 10,926 patients were included in the analysis and divided equally into the ACEI and CCB groups. Mean patient age was 65 years. The adjusted hazards ratio (95% confidence interval [CI]) in the ACEI versus CCB groups for the entire follow-up period was 0.85 (95% CI: 0.74 to 0.97) for new-onset AF, and the adjusted incidence ratio for AF-related hospitalizations was 0.74 (95% CI: 0.62 to 0.89).

CONCLUSIONS

Angiotensin-converting enzyme inhibition was associated with a reduced incidence of AF for patients with hypertension in a usual care setting. These results need to be confirmed in a large-scale randomized clinical trial.

Impact of informed consent requirements on cardiac arrest research in the United States: exception from consent or from research?

INTRODUCTION

Research in patients with life-threatening illness such as cardiac arrest is challenging since they can not consent. The Food and Drug Administration addressed research under emergency conditions by publishing new criteria for exception from informed consent in 1996. We systematically reviewed randomized trials over a 10-year period to assess the impact of these regulations.

METHODS

Case-control study of published trials for cardiac arrest (cases) and atrial fibrillation (controls.) Studies were identified by using structured searches of MEDLINE and EMBASE from 1992 to 2002. Included were studies using random allocation in humans with cardiac arrest or atrial fibrillation prior to enrollment. Excluded were duplicate publications. Number of American trials, foreign trials and proportion of trials of American origin were compared by using regression analysis. Changes in cardiac arrest versus atrial fibrillation trials were calculated as risk differences.

RESULTS

Of 4982 identified cardiac arrest studies, 57 (1.1%) were randomized trials. The number of American cardiac arrest trials decreased by 15% (95% CI: 8, 22%) annually (P = 0.05). The proportion of cardiac arrest trials of American origin decreased by 16% (95% CI: 10, 22%) annually (P = 0.006). Of 5596 identified atrial fibrillation studies, 197 trials (3.5%) were randomized trials. The risk difference between cardiac arrest versus atrial fibrillation trials being of American origin decreased significantly (annual difference -5.8% (95% CI: -10, -0.1%), P = 0.03).

INTERPRETATION

Fewer American cardiac arrest trials were published during the last decade, when federal consent requirements changed. Regulatory requirements for clinical trials may inhibit improvements in care and threaten public health.

Enalapril treatment and hospitalization with atrial tachyarrhythmias in patients with left ventricular dysfunction

BACKGROUND

Experimental and clinical evidence suggests a preventive role for agiotensin-coverting enzyme (ACE) inhibitors on the development of atrial fibrillation. However, the effect of ACE inhibition on hospitalization with atrial tachyarrhythmias in patients with left ventricular (LV) dysfunction is not known. We sought to determine whether enalapril treatment reduced hospitalizations with atrial tachyarrhythmias in patients with LV dysfunction.

METHODS

We performed a retrospective analysis of the Studies of Left Ventricular Dysfunction (SOLVD) trial. Hospitalizations with atrial tachyarrhythmias were noted.

RESULTS

A total of 192 hospitalizations with atrial tachyarrhythmias occurred in 158 patients during a follow-up period of 34 months. The time to first hospitalization with atrial tachyarrhythmias or death was significantly lower in the enalapril group (P =.005). In a multivariate analysis adjusting for the presence of atrial fibrillation at study entry, enalapril treatment was associated with a reduction in the rate of hospitalization with atrial tachyarrhythmias or death (RR, 0.87; 95% CI, 0.79-0.96; P =.007). The incidence of hospitalization with atrial tachyarrhythmias was 7.9 hospitalizations per 1000 patient-years of follow-up in the enalapril group, compared with 12.4 per 1000 patient-years in the placebo group (RR, 0.64; 95% CI, 0.48-0.85; P =.002).

CONCLUSION

Enalapril is associated with a decreased incidence of hospitalization with atrial tachyarrhythmias in patients with LV dysfunction.

Angiotensin-converting enzyme inhibitors as adjunctive therapy in patients with persistent atrial fibrillation

OBJECTIVES

The purpose of the current study was to assess the effect of angiotensin-converting enzyme inhibitor (ACEI) therapy in facilitating cardioversion from persistent atrial fibrillation (AF) and maintaining sinus rhythm.

BACKGROUND

Pharmacologic therapy and electrical cardioversion for AF are often unsuccessful in maintaining long-term sinus rhythm.

METHODS

The current study, a 1-year, prospective follow-up, comprised 47 patients with persistent AF undergoing electrical cardioversion. Patients receiving ACEI were compared with those receiving other medications. The study end point was the number of defibrillation attempts required for atrial defibrillation and the number of hospital admissions. A secondary end point was change in signal-averaged P-wave duration (SAPD) 1 year after successful electrical cardioversion.

RESULTS

Of those admitted and requiring electrical defibrillation, the number of defibrillation attempts required for successful cardioversion was significantly less in the ACEI group (P <.001). The incidence rate ratio for admissions comparing recipients of ACEI with others was 0.14 (P =.03). Patients receiving ACEI therapy had significantly lower SAPD at 1 year when compared with the no-ACEI group (135 ms +/- 3 vs 150 ms +/- 2, P =.002).

CONCLUSIONS

The use of long-term ACEI therapy facilitated electrical defibrillation in patients with persistent AF. ACEI therapy also reduced SAPD, suggesting amelioration of the arrhythmogenic substrate. Furthermore, we confirmed that SAPD is prolonged in patients with persistent AF.

Renin-Angiotensin System Gene Polymorphisms and Atrial Fibrillation

BACKGROUND

The activated local atrial renin-angiotensin system (RAS) has been reported to play an important role in the pathogenesis of atrial fibrillation (AF). We hypothesized that RAS genes might be among the susceptibility genes of nonfamilial structural AF and conducted a genetic case-control study to demonstrate this.

METHODS AND RESULTS

A total of 250 patients with documented nonfamilial structural AF and 250 controls were selected. The controls were matched to cases on a 1-to-1 basis with regard to age, gender, presence of left ventricular dysfunction, and presence of significant valvular heart disease. The ACE gene insertion/deletion polymorphism, the T174M, M235T, G-6A, A-20C, G-152A, and G-217A polymorphisms of the angiotensinogen gene, and the A1166C polymorphism of the angiotensin II type I receptor gene were genotyped. In multilocus haplotype analysis, the angiotensinogen gene haplotype profile was significantly different between cases and controls (chi2=62.5, P=0.0002). In single-locus analysis, M235T, G-6A, and G-217A were significantly associated with AF. Frequencies of the M235, G-6, and G-217 alleles were significantly higher in cases than in controls (P=0.000, 0.005, and 0.002, respectively). The odds ratios for AF were 2.5 (95% CI 1.7 to 3.3) with M235/M235 plus M235/T235 genotype, 3.3 (95% CI 1.3 to 10.0) with G-6/G-6 genotype, and 2.0 (95% CI 1.3 to 2.5) with G-217/G-217 genotype. Furthermore, significant gene-gene interactions were detected by the multifactor-dimensionality reduction method and multilocus linkage disequilibrium tests.

CONCLUSIONS

This study demonstrates the association of RAS gene polymorphisms with nonfamilial structural AF and may provide the rationale for clinical trials to investigate the use of ACE inhibitor or angiotensin II antagonist in the treatment of structural AF.

Nonchannel drug targets in atrial fibrillation

Atrial fibrillation (AF) is the most common clinical arrhythmia and one of the most important factors for ischemic stroke. In general, AF is treated with "channel-blocking drugs" to restore sinus rhythm and warfarin is recommended in the majority of patients to prevent atrial thrombus formation and thromboembolic events. In the recent years, a tremendous amount has been learned about the pathophysiology and molecular biology of AF. Thus, pharmacologic interference with specific signal transduction pathways with "non-channel-blocking drugs" appears promising as a novel antiarrhythmic approach to maintain sinus rhythm and to prevent atrial clot formation. Therefore, this review will highlight some novel "nonchannel drug targets" for AF therapy.

Antiarrhythmic drug therapy of atrial fibrillation

In the post-AFFIRM era, treatment of AF has become the treatment of symptoms. In some patients, this will be simple rate control, but there remain a significant cohort of patients in whom rate control alone does not give acceptable symptom relief. In this group, antiarrhythmic therapy still has a role, and the AFFIRM trial indicates that this therapeutic strategy is without significant deleterious effect on mortality. The choice of antiarrhythmic agent must be individualized according to underlying cardiac pathologies and comorbidities, however. Most recently, the introduction of dofetilide has widened the therapeutic options in patients with severe heart disease, and the Canadian Trial of Atrial Fibrillation indicated the superior efficacy of amiodarone at low doses. The release/ development of newer Class III antiarrhythmic agents may offer hope for the benefits of amiodarone without the serious adverse effects with long-term therapy.

Atrial fibrillation: guiding lessons from epidemiology

The epidemiology of AF is a challenging and surprising area of medical knowledge. The prevalence of AF may be not changing despite the common perception. It is possible that being earlier disease of the middle age, and because of changing etiology and successful treatment of underlying vascular conditions, AF is shifting to the elderly population. In this population, it becomes more clinically significant, and increasingly leads to disability and death. Screening procedures for silent AF likely are underimplemented and may change understanding of AF epidemiology significantly. Hypertension may be the most common primary etiology of AF, and the possibility of effective primary prevention of AF by strict control of hypertension needs to be evaluated adequately.

Electrical cardioversion of atrial fibrillation

External direct current cardioversion remains the most common and effective method for restoration of normal sinus rhythm in patients with persistent AF. The development of biphasic defibrillators allows for higher success rates of conversion using standard energy levels. For persistent AF, an initial energy of 200 J is recommended for biphasic defibrillators, and 300 to 360 J are recommended for monophasic defibrillators, with the electrodes placed in the anterior posterior position. For refractory cases, alternatives are available such as dual defibrillators or internal cardioversion. Antiarrhythmic drugs may enhance the results of cardioversion by helping overcome shock failure or by preventing immediate recurrence of AF. Thromboembolism is the most important complication associated with cardioversion, but it can be prevented by providing 3 weeks of anticoagulation before the procedure or by excluding the presence of thrombi by transesophageal echocardiography, followed by an additional 4 weeks of anticoagulation.

Expression of angiotensin II receptors in human left and right atrial tissue in atrial fibrillation with and without underlying mitral valve disease

TIVES: We postulated a change of angiotensin II receptor subtype expression in patients with lone atrial fibrillation (AF) and AF with underlying mitral valve disease (MVD) both compared with sinus rhythm (SR).

BACKGROUND

Atrial fibrillation is a progressive disease associated with electrical and structural remodeling. Angiotensin II (ANGII) is involved in the process of myocardial remodeling. Actions of ANGII are mediated by ANGII receptor subtypes 1 and 2 (AT(1) and AT(2)).

METHODS

Left atrial (LA) and right atrial (RA) tissue samples were obtained from patients with AF or SR with or without underlying MVD. The AT(1) and AT(2) protein levels were measured by quantitative Western blotting techniques.

RESULTS

The AT(1) protein level in the LA was significantly increased in patients with AF (all forms) compared with SR (p < 0.05), whereas AT(2) expression was not significantly altered. Comparison of the subgroups revealed a similar increase of AT(1) in both paroxysmal AF and chronic AF with or without MVD. Additionally, investigations of ANGII receptor subtypes in the RA did not exhibit any significant changes either in AT(1) or in AT(2) in patients with AF versus SR. Underlying MVD did not significantly affect AT(2) receptor subtype expression in LA.

CONCLUSIONS

Atrial fibrillation is associated with an up-regulation of AT(1) in LA, but not in RA, and did not appear to influence the AT(2) expression in the atrium. Because we found an enhanced expression of AT(1)in the LA, we conclude that AT(1) might be involved in the pathogenesis of AF in the LA.

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

Clinical trials assessing the efficacy of anti- arrhythmic drugs for terminating atrial fibrillation have demonstrated that rate control drugs have little to no added efficacy compared to placebo; however, spontaneous conversion of recent-onset atrial fibrillation is common. Antiarrhythmic drugs such as oral dofetilide, oral bolus-flecainide and propafenone and intravenous ibutilide all have a role in terminating atrial fibrillation. Active comparator trials have demonstrated that amiodarone is more efficacious in maintaining sinus rhythm than propafenone and sotalol. Multiple trials have demonstrated the safety of amiodarone, sotalol, dofetilide and azimilide in a post-myocardial infarction population and amiodarone and dofetilide in a congestive heart failure population. Newer antiarrhythmic agents, some with novel mechanisms of action, will add to the pharmacologic armamentarium in treating atrial fibrillation.

Hybrid therapy of atrial fibrillation: algorithms and outcome

Rhythm control methods have not shown superior outcomes to rate control strategies in atrial fibrillation. Newer approaches to rhythm control employ "hybrid" therapies combining pharmacologic and non pharmacologic interventions. Pathophysiologic insights into mechanisms of atrial fibrillation (AF) suggest that arrhythmogenesis is due to interactions of multiple triggering rhythms and a complex electrophysiologic substrate resulting in the emergence of multiple tachyarrhythmias, often in disparate locations that may coexist in time. Thus, an "hybrid" therapy prescription is more likely to address several of the etiologic factors culminating in clinical AF. Results of pilot clinical studies of hybrid therapy are encouraging and involve drugs, devices and ablation techniques in varying permutations. Hybrid therapy algorithms using right heart procedures can improve efficacy with potentially lower risk. Considerations in implementation of these algorithms include staged or simultaneous interventions and a right versus left heart strategy. The parallel with the current coronary disease management paradigm is obvious and relevant.