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

Association of the angiotensinogen M235T polymorphism with recurrence after catheter ablation of acquired atrial fibrillation

PURPOSE

Previous studies showed that genetic variants of the angiotensinogen (AGT) gene conferred higher risk for acquired atrial fibrillation (AF). The present study investigated whether AGT variants correlate with the clinical outcome in patients with acquired AF after catheter ablation (CA).

METHODS

A total of 150 acquired symptomatic drug-refractory AF patients (mean age 63.7±11.0 years, 24.6% non-paroxysmal AF) with acquired AF underwent a single CA procedure in our department and were included in this retrospective analysis. Eight tagging single nucleotide polymorphisms (tSNPs) in the AGT gene were genotyped. Standard electrocardiographs (ECGs) and 24-hour Holter recordings were performed during a median follow-up period of 57.5 months to detect AF recurrence.

RESULTS

Sixty-one patients (40.7%) suffered AF recurrences after a single CA procedure during follow up. Of the eight tSNPs, the frequency of the M allele of M235T was significantly higher in the recurrence group (28%) compared to the non-recurrence group (18%) (p=0.042). The recurrence rates of patients with the TT, MT, and MM genotypes were 34.4%, 50%, and 55.6%, respectively (ptrend=0.049). After adjusting for age, sex, body mass index, hypertension, left atrial volume index (LAVI) and other covariates, M235T increased the risk of AF recurrence in additive and dominant models with odds ratios of 2.023 (95% confidence interval (CI): 1.034-3.926, p=0.033) and 2.601 (95% CI: 1.102-6.056, p=0.025), respectively. However, in multiple correction analyses, the p values of multiple comparisons were not statistically significant (pcorrect>0.05).

CONCLUSIONS

The M allele of M235T might be associated with an increased risk of AF recurrence after CA. Genotyping may thus be helpful on identifying patients with higher risks of AF recurrence after CA and developing optimal follow-up strategies. These strategies may differ and should be individualized according to patients' genotype. Future studies are warranted to validate the potential effect of AGT M235T on AF recurrence post CA.

Blood Pressure and Atrial Fibrillation: A Combined AF-CHF and AFFIRM Analysis

BACKGROUND

Hypertension is an established risk factor for new-onset atrial fibrillation (AF). However, the relationship between blood pressure and recurrent AF is less well understood.

METHODS AND RESULTS

A pooled analysis of patient-level data from AFFIRM and AF-CHF trials was conducted on all 2,715 patients with paroxysmal or persistent AF, 68 ± 8 years, 66% male, randomized to rhythm control and followed for 40.6 ± 16.5 months. We assessed the impact of a baseline systolic blood pressure (SBP; <120 mmHg [N = 1,008], 120-140 mmHg [N = 930], >140 mmHg [N = 777]) on recurrent AF and proportion of time spent in AF. In patients with LVEF >40% (N = 1,719), SBP was not associated with recurrent AF in multivariate regression analyses (P = 0.752). In contrast, in patients with LVEF ≤40% (N = 996), the AF recurrence rate was higher in those with an SBP >140 mmHg compared to 120-140 mmHg (hazard ratio 1.47; 95% CI [1.12-1.93], P = 0.005). The rate of recurrent AF was similar in patients with SBP <120 mmHg compared to 120-140 mmHg (hazard ratio 1.15; 95% CI [0.92-1.43], P = 0.225). Consistently, the proportion of time spent in AF was not influenced by SBP in patients with LVEF >40% (P = 0.645). However, in patients with LVEF ≤40%, the adjusted mean proportion of time spent in AF was 17.2% if SBP was <120 mmHg, 15.4% for SBP 120-140 mmHg, and 24.0% for SBP >140 mmHg (P = 0.025).

CONCLUSION

Systolic blood pressure is an important determinant of recurrent AF and overall AF burden in patients with left ventricular dysfunction (LVEF≤40%) but not in those with preserved ventricular function.

Effect of telmisartan on atrial fibrillation recurrences in patients with hypertension: a systematic review and meta-analysis

BACKGROUND

The systematic review and meta-analysis are to evaluate the effect of t Telmisartan on atrial fibrillation (AF) recurrences in hypertensive patients with paroxysmal AF.

METHODS

MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched. Random controlled trials (RCTs) were conducted in which telmisartan was compared to other antihypertensive drugs for AF recurrences prevention in hypertensive patients with paroxysmal AF. A systematic review and meta-analysis based on aggregate data extracted from the included studies were carried out to assess the telmisartan in preventing AF relapse. The efficacy outcome was the incidence of AF recurrences. Hazard ratios (HRs) were calculated from published summary statistics and combined to give pooled estimates of efficacy.

RESULTS

This meta-analysis comprised four studied including 1050 hypertensive patients (537 men and 513 women; mean age 63; mean blood pressure (BP) 156/94 mmHg). With the similar BP control, the AF recurrences rate was significantly lower in the telmisartan-treated patients than in the other antihypertensive drugs-treated patients (HR 0.54, CI 0.34-0.86, P < 0.05).

CONCLUSION

The results of this review and meta-analysis indicate that telmisartan seems to be more effective than other antihypertensive drugs in preventing AF recurrences among hypertensive patients with paroxysmal AF.

Beneficial effects of losartan for prevention of paroxysmal atrial fibrillation in patients with sick sinus syndrome: analysis with memory function of pacemaker

Renin-angiotensin system (RAS) inhibitors may be useful in preventing the occurrence of paroxysmal atrial fibrillation (PAF). However, evaluation of such effect is difficult because many PAF episodes are asymptomatic and not all episodes are detected by intermittent electrocardiographic monitoring. A pacemaker has been developed with dedicated functions for AF detection and electrocardiogram storage. Accordingly, we examined the effect of losartan, an angiotensin receptor blocker on PAF occurrence using this new modality. We enrolled 70 consecutive patients who had undergone dual-chamber pacemaker implantation for sick sinus syndrome. Finally, 62 patients participated in the study. Thirty patients were randomized to the losartan group (mean 43 ± 12 mg/day) and 32 patients to the control group. They were followed up for 3 months. The frequency, the maximum duration and the total duration of PAF recorded by the stored electrocardiograms for the last 1 month during the observation period and study period were compared between the two groups. The change in the frequency of PAF from the observation period in the losartan and control groups was similar (-35 ± 25 vs. -67 ± 62 times; NS). However, the change in the maximum duration and the total duration of PAF was significantly shorter in the losartan group than in the control group (-493 ± 158 vs. -10 ± 69 min; p < 0.05, and -4007 ± 2334 vs. 1119 ± 714 min; p < 0.05, respectively). Losartan suppressed the maximum duration and the total duration of PAF in patients with sick sinus syndrome without hemodynamic changes. This is the first study to show the effect of a renin-angiotensin system inhibitor on the secondary prevention of PAF using the dedicated functions of a pacemaker for PAF detection and electrocardiogram storage.

The cost-effectiveness of irbesartan for hypertension

High blood pressure is a very common problem in the adult and elderly population, both in developed and developing countries. A relatively large number of drug classes are available to treat this condition and prevent its complications, which are not only more frequent in the aforementioned patients but also those affected by metabolic syndrome and/or Type 2 diabetes. Irbesartan is an angiotensin-receptor blocker class drug with good antihypertensive efficacy and specific pharmacological characteristics, whose efficacy has been more deeply evaluated in metabolically complex hypertensive patients. In this review, the authors will analyze its effectiveness in preventing or delaying organ damage in hypertensive patients, with a closer look at the economic implications of treating hypertension with irbesartan in the context of available antihypertensive drugs.

Upregulation of SERCA2a following short-term ACE inhibition (by enalaprilat) alters contractile performance and arrhythmogenicity of healthy myocardium in rat

Chronic angiotensin-converting enzyme inhibitor (ACEIs) treatment can suppress arrhythmogenesis. To examine whether the effect is more immediate and independent of suppression of pathological remodelling, we tested the antiarrhythmic effect of short-term ACE inhibition in healthy normotensive rats. Wistar rats were administered with enalaprilat (ENA, i.p., 5 mg/kg every 12 h) or vehicle (CON) for 2 weeks. Intraarterial blood pressure in situ was measured in A. carotis. Cellular shortening was measured in isolated, electrically paced cardiomyocytes. Standard 12-lead electrocardiography was performed, and hearts of anaesthetized open-chest rats were subjected to 6-min ischemia followed by 10-min reperfusion to examine susceptibility to ventricular arrhythmias. Expressions of calcium-regulating proteins (SERCA2a, cardiac sarco/endoplasmic reticulum Ca(2+)-ATPase; CSQ, calsequestrin; TRD, triadin; PLB, phospholamban; Thr(17)-PLB-phosphorylated PLB at threonine-17, FKBP12.6, FK506-binding protein, Cav1.2-voltage-dependent L-type calcium channel alpha 1C subunit) were measured by Western blot; mRNA levels of L-type calcium channel (Cacna1c), ryanodine receptor (Ryr2) and potassium channels Kcnh2 and Kcnq1 were measured by qRT-PCR. ENA decreased intraarterial systolic as well as diastolic blood pressure (by 20%, and by 31%, respectively, for both P < 0.05) but enhanced shortening of cardiomyocytes at basal conditions (by 34%, P < 0.05) and under beta-adrenergic stimulation (by 73%, P < 0.05). Enalaprilat shortened QTc interval duration (CON 78 ± 1 ms vs. ENA 72 ± 2 ms; P < 0.05) and significantly decreased the total duration of ventricular fibrillations (VF) and the number of VF episodes (P < 0.05). Reduction in arrhythmogenesis was associated with a pronounced upregulation of SERCA2a (CON 100 ± 20 vs. ENA 304 ± 13; P < 0.05) and complete absence of basal Ca(2+)/calmodulin-dependent phosphorylation of PLB at Thr(17). Short-term ACEI treatment can provide protection against I/R injury-induced ventricular arrhythmias in healthy myocardium, and this effect is associated with increased SERCA2a expression.

Glycogen and the propensity for atrial fibrillation: intrinsic anatomic differences in glycogen in the left and right atria in the goat heart

Background:

Previous experimental studies have demonstrated electrophysiological and structural remodeling in pacing induced atrial fibrillation. The latter has been characterized by glycogen accumulation but no connection to atrial fibrillation induction and maintenance has as yet been proposed.

Aims:

We determined the presence of glycogen in the right and left atrial appendages in the goat heart, in order to find any intrinsic disparity in distribution and concentration between these sites.

Materials and Methods:

Atrial appendages from 5 goats were stained by the Periodic acid Schiffmethod to determine the presence of glycogen and the concentration of glycogen by morphometric analysis.

Results:

We are reporting for the first time that the right atrial appendage showed scattered glycogen granules throughout the atrial myocytes which delineated the intercalated discs; whereas glycogen in the left atrial appendage was more dense within cells and coalesced against the intercalated discs and side to side junctions between myocytes. Also, morphometric analysis determined that the stained regions of the right atrial appendages averaged, 0.8 ± 1.3 μm² compared to the left atrial appendage sections, 2.6 ± 3 μm², P = 0.02. We show that glycogen is heterogeneously distributed in both atria in the normal goat heart; however, the density of glycogen deposits concentrating against the intercalated discs and side to side connections in the left atrial appendage is a critically distinct difference. Impediment of cell to cell conduction could result in a non-uniform wavefront of activation, with areas of slowed conduction, predisposing the left atrium to reentrant based atrial fibrillation.

Conclusion:

These findings provide a basis for the well-known greater propensity for atrial fibrillation in the left versus the right atrium.

The efficacy and tolerability of commonly used agents to prevent recurrence of atrial fibrillation after successful cardioversion

A number of therapeutic strategies exist for the restoration and maintenance of sinus rhythm in patients presenting with atrial fibrillation. The acute success rate with electrical cardioversion is high. However, many patients relapse into atrial fibrillation. A major challenge faced by those who care for patients with atrial fibrillation is the long-term maintenance of sinus rhythm whilst avoiding treatment-related adverse effects. This review examines the efficacy and tolerability of conventional anti-arrhythmic drugs for the secondary prevention of atrial fibrillation in the post-cardioversion period.

Renin-angiotensin system inhibitors prevent the recurrence of atrial fibrillation: a meta-analysis of randomized controlled trials

OBJECTIVE

This study was designed to assess whether angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) could prevent the recurrence of atrial fibrillation (AF).

METHODS

A systemic literature search of PubMed, EMBASE, and Cochrane Controlled Trials Register till 2012 was performed to identify randomized controlled trials involving the prevention of recurrence of AF with renin-angiotensin system blockade therapy. Subgroup analysis and meta-regression were performed. Publication bias was checked through funnel plot and Egger's test.

RESULTS

Twenty-one randomized controlled trials including 13,184 patients with AF were identified. Overall, the recurrence of AF was significantly reduced in patients using ACEI/ARBs [odds ratio (OR), 0.43; 95% confidence interval (CI), 0.32-0.56; P < 0.00001], especially both in irbesartan subgroup (OR, 0.38; 95% CI, 0.21-0.68; P = 0.001) and in patients receiving antiarrhythmic drug (AAD) (OR, 0.37; 95% CI, 0.29-0.48; P < 0.00001), and there was no significant difference between ACEIs and ARBs (ACEIs: OR, 0.42; 95% CI, 0.31-0.57 and ARBs: OR, 0.42; 95% CI, 0.31-0.57). Moreover, it was found that the benefits of ACEI/ARBs revealed positive correlation to systolic blood pressure (regression coefficient: -0.0700257, P = 0.000) in no-AAD users.

CONCLUSIONS

ACEI/ARBs are effective on the secondary prevention of AF, especially in patients receiving AAD and suffering from hypertension.

Angiotensin-(1-7) prevent atrial tachycardia induced sodium channel remodeling

BACKGROUND

Activation of the renin-angiotensin system plays an important role in atrial electrical remodeling; angiotensin-(1-7) (Ang-(1-7)) counterbalances the actions of angiotensin II. The aim of this study was to determine the effects of Ang-(1-7) on cardiac sodium current (INa ) in a canine model of atrial tachycardia.

METHODS

Eighteen dogs were randomly assigned to sham, pacing, or pacing + Ang-(1-7) groups (n = 6 in each group). Rapid atrial pacing (500 beats/min) was maintained for 2 weeks, while the dogs in the sham group were not paced. Ang-(1-7) (6 μg/kg/h) was administered intravenously during pacing. Whole-cell patch clamp techniques were utilized to record INa from canine atrial myocytes. Reverse transcription-polymerase chain reaction was used to assess possible underlying changes in cardiac Na(+) channels (Nav1.5).

RESULTS

Our results showed that INa density and expression of the Nav1.5 mRNA significantly decreased following pacing (P < 0.05 vs sham); however, the half-activation voltage (V1/2act ) and half-inactivation voltage (V1/2inact ) of INa were not significantly altered (P > 0.05 vs sham). Ang-(1-7) treatment significantly increased INa densities and hyperpolarized V1/2act without concomitant changes in V1/2inact but have no effect on the expression of the Nav1.5 gene.

CONCLUSIONS

Ang-(1-7) significantly increased INa densities, which contributed to improving intraatrial conduction and decreasing the likelihood of atrial fibrillation maintenance.

The Role Of Renin Angiotensin System In Atrial Fibrillation

Atrial fibrillation (AF) is the most prevalent arrhythmia and its incidence is on the rise. AF causes significant morbidity and mortality leading to rising AF-related health care costs. There is experimental and clinical evidence from animal and human studies that suggests a role for the renin angiotensin system (RAS) in the etiopathogenesis of AF. This review appraises the current understanding of RAS antagonism, using angiotensin converting enzyme inhibitors (ACE-I), angiotensin receptor blockers (ARB) and aldosterone antagonists (AA), for prevention of AF. RAS antagonism has proven to be effective for primary and secondary prevention of AF in subjects with heart failure and left ventricular (LV) dysfunction.However, most of the evidence for the protective effect of RAS antagonism is from clinical trials that had AF as a secondary outcome or from unspecified post-hoc analyses. The evidence for prevention in subjects without heart failure and with normal LV function is not as clear. RAS antagonism, in the absence of concomitant antiarrhythmic therapy, was not shown to reduce post cardioversion AF recurrences. RAS antagonism in subjects undergoing catheter ablation has also been ineffective in preventing AF recurrences.

Targeting inflammation and oxidative stress in atrial fibrillation: role of 3-hydroxy-3-methylglutaryl-coenzyme a reductase inhibition with statins

SIGNIFICANCE

Atrial fibrillation (AF) is a burgeoning health-care problem, and the currently available therapeutic armamentarium is barely efficient. Experimental and clinical evidence implicates inflammation and myocardial oxidative stress in the pathogenesis of AF.

RECENT ADVANCES

Local and systemic inflammation has been found to both precede and follow the new onset of AF, and NOX2-dependent generation of reactive oxygen species in human right atrial samples has been independently associated with the occurrence of AF in the postoperative period in patients undergoing cardiac surgery. Anti-inflammatory and antioxidant agents can prevent atrial electrical remodeling in animal models of atrial tachypacing and the new onset of AF after cardiac surgery, suggesting a causal relationship between inflammation/oxidative stress and the atrial substrate that supports AF.

CRITICAL ISSUES

Statin therapy, by redressing the myocardial nitroso-redox balance and reducing inflammation, has emerged as a potentially effective strategy for the prevention of AF. Evidence indicates that statins prevent AF-induced electrical remodeling in animal models of atrial tachypacing and may reduce the new onset of AF after cardiac surgery. However, whether statins have antiarrhythmic properties in humans has yet to be conclusively demonstrated, as data from randomized controlled trials specifically addressing the relevance of statin therapy for the primary and secondary prevention of AF remain scanty.

FUTURE DIRECTIONS

A better understanding of the mechanisms underpinning the putative antiarrhythmic effects of statins may afford tailoring AF treatment to specific clinical settings and patient's subgroups. Large-scale randomized clinical trials are needed to support the indication of statin therapy solely on the basis of AF prevention.

Antihypertensive strategy based on angiotensin II receptor blockers: a new gateway to reduce risk in hypertension

Effective treatment of high blood pressure levels represents a key strategy for reducing global cardiovascular risk. Other factors, beyond blood pressure control, however, appear to be of potential relevance in reducing the risk related to hypertension. Recent clinical trials have demonstrated that those pharmacological agents that counteract the renin-angiotensin system may confer additional clinical benefits across the spectrum of cardiovascular disease, beyond their blood pressure-lowering properties. These studies are largely based on the use of an antihypertensive strategy, based on the association between angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers (ARBs) and low-dose thiazide diuretics or calcium channel blockers. Over the last few decades, clinical trials have also tested the potential effects of combination therapy based on the association between angiotensin-converting enzyme inhibitors or ARBs and other renin-angiotensin system-blocking agents, including mineralocorticoid receptor antagonists and, more recently, renin inhibitors. This review highlights the evidence derived from recent clinical trials, supporting a role for pharmacological strategies based on ARBs in primary and secondary prevention of cardiovascular and renal disease.

Renin Angiotenin Blocker Pre-treatment and Recurrence After Pulmonary Vein Isolation in Patients with Paroxysmal and Persistent Atrial Fibrillation

Introduction: Pulmonary venous isolation has emerged as an effective method for preventing atrial fibrillation (AF) recurrence. Yet, recurrence is common. Angiotensin-receptor-blockers (ARBs) and angiotensin-converting-enzyme-inhibitors (ACEI) are effective in reducing the extent of myocardial remodeling and fibrosis. Our aim was to study whether pretreatment with ARBs and ACEI was effective in decreasing recurrence after pulmonary vein isolation for patients with AF. Methods: Three hundred and twelve consecutive patients who underwent ablation from 12/2006 until 7/2010 were followed for at least one year. All patients underwent MRI before ablation to assess atrial fibrosis. Data include demographic characteristics, comorbidities, AF type and information regarding treatment with ACEI or ARBs. Results: Most patients were men (62%), mean age was 64. Hypertension (HTN) was present in 60%. Their mean ejection fraction was 60%. There were 104 patients (33.3%) treated with ACEI, and 13.5 % were treated with ARBs prior to ablation. Ninety seven patients (31.1%) had AF recurrence. AF type was a significant predictor for recurrence (recurrence with paroxysmal, persistent and long-standing persistent: 23.75, 37.3 and 60%, respectively, p=0.005). The most important factor predicting recurrence was increased pre-ablation atrial fibrosis (p<0.0001). Recurrence was more frequent in patients treated with ACEI (40.4% vs 26.4% untreated patients, p=0.012). In the ARB treated group, 38.1% vs 30.0% untreated experienced recurrence (p=0.3). After multivariable adjustment for demographics, risk factors and atrial fibrosis, treatment with ACEI was associated with increased rate of recurrence in patients with persistent AF (hazard ratio: 2.6, p=0.003). There was no significant relation between ACEI pretreatment and recurrence in patients with paroxysmal AF (HR- 0.83, p=0.7), or between ARB pre-treatment and recurrence in patients with paroxysmal as well as persistent AF (p=0.2 and 0.53, respectively). Conclusions: Pretreatment with ACEI or ARBs is not associated with reduced recurrence rate in patients with paroxysmal or persistent AF undergoing ablation.

The past, present and future of renin-angiotensin aldosterone system inhibition

The renin-angiotensin aldosterone system (RAAS) is central to the pathogenesis of cardiovascular disease. RAAS inhibition can reduce blood pressure, prevent target organ damage in hypertension and diabetes, and improve outcomes in patients with heart failure and/or myocardial infarction. This review presents the history of RAAS inhibition including a summary of key heart failure, myocardial infarction, hypertension and atrial fibrillation trials. Recent developments in RAAS inhibition are discussed including implementation and optimization of current drug therapies. Finally, ongoing clinical trials, opportunities for future trials and issues related to the barriers and approvability of novel RAAS inhibitors are highlighted.

The Progressive Nature of Atrial Fibrillation:A Rationale for Early Restoration and Maintenance of Sinus Rhythm

Atrial fibrillation (AF) is the manifest outcome of a multifactorial, progressive disease process,secondarily or primarily involving the atrial chambers. The slowly progressive electrostructural alterations diffusely involve the atrial substrate and lead to persistent and permanent forms of AF. Although the progression of the AF disease process is variable and associated with the development of comorbid conditions, rhythm restoration therapies, particularly catheter ablation,provide higher acute and long-term success rates in paroxysmal than non-paroxysmal AF. This review of literature aims to discuss how early restoration and maintenance of sinus rhythm especially using novel approaches can influence the progressive nature of atrial fibrillation.

During ablation for atrial fibrillation, is simultaneous renal artery ablation appropriate?

Over the past few decades, the mainstay of hypertension management has been pharmacological therapy; however, there is now a growing body of evidence that drug-resistant hypertension can be managed effectively by renal artery ablation. Several studies have documented the feasibility and safety of this treatment, although data regarding long-term outcomes are still emerging. Atrial fibrillation (AF) and hypertension commonly coexist, and recent work has demonstrated improved outcomes from catheter ablation of AF with concomitant renal artery denervation at little extra cost in terms of time and resource. The aim of this review is to explore the link between hypertension and AF, the synergistic effect of renal artery ablation on AF ablation, explain how this may work and address unanswered questions.

Routine versus aggressive upstream rhythm control for prevention of early atrial fibrillation in heart failure: background, aims and design of the RACE 3 study

Background

Rhythm control for atrial fibrillation (AF) is cumbersome because of its progressive nature caused by structural remodelling. Upstream therapy refers to therapeutic interventions aiming to modify the atrial substrate, leading to prevention of AF.

Objective

The Routine versus Aggressive upstream rhythm Control for prevention of Early AF in heart failure (RACE 3) study hypothesises that aggressive upstream rhythm control increases persistence of sinus rhythm compared with conventional rhythm control in patients with early AF and mild-to-moderate early systolic or diastolic heart failure undergoing electrical cardioversion.

Design

RACE 3 is a prospective, randomised, open, multinational, multicenter trial. Upstream rhythm control consists of angiotensin converting enzyme inhibitors and/or angiotensin receptor blockers, mineralocorticoid receptor antagonists, statins, cardiac rehabilitation therapy, and intensive counselling on dietary restrictions, exercise maintenance, and drug adherence. Conventional rhythm control consists of routine rhythm control therapy without cardiac rehabilitation therapy and intensive counselling. In both arms, every effort is made to keep patients in the rhythm control strategy, and ion channel antiarrhythmic drugs or pulmonary vein ablation may be instituted if AF relapses. Total inclusion will be 250 patients. If upstream therapy proves to be effective in improving maintenance of sinus rhythm, it could become a new approach to rhythm control supporting conventional pharmacological and non-pharmacological rhythm control.

Use of evidence-based cardiac prevention therapy among outpatients with atrial fibrillation

BACKGROUND

Patients with atrial fibrillation often have cardiovascular risk factors or known comorbid disease, yet the use of evidence-based primary and secondary prevention cardiac therapy among atrial fibrillation outpatients is unknown.

METHODS

Using baseline data collected between June 2010 and August 2011 from 174 sites participating in ORBIT-AF, a US national registry of patients with atrial fibrillation coordinated from Durham, NC, we examined professional guideline-recommended evidence-based therapy use for cardiovascular comorbid conditions and risk factors. Multivariable logistic regression was used to identify factors associated with receipt of all indicated evidence-based therapy.

RESULTS

Among 10,096 enrolled patients, 93.5% were eligible for one or more evidence-based therapies. Among those eligible, 46.6% received all indicated therapies: 62.3% received an antiplatelet agent, 72.3% received a beta-blocker, 59.5% received an angiotensin-converting enzyme or angiotensin receptor blocker, 15.3% received an aldosterone antagonist, 65.7% received a statin, and 58.8% received an implantable cardioverter-defibrillator. A minority of patients with coronary artery disease, diabetes mellitus, heart failure, and peripheral vascular disease received all indicated therapies (25.1%, 43.2%, 42.5%, and 43.4%, respectively). A total of 52.4% of patients had controlled hypertension and 74.6% of patients with hyperlipidemia received a statin. Factors associated with nonreceipt of all indicated therapies included frailty, comorbid illness, geographic region, and antiarrhythmic drug therapy.

CONCLUSIONS

The majority of eligible atrial fibrillation outpatients did not receive all guideline-recommended therapies for cardiovascular comorbid conditions and risk factors. This represents a potential opportunity to improve atrial fibrillation patients' quality of care and outcomes.

Traditional Heart Failure Medications and Sudden Cardiac Death Prevention

Sudden cardiac death (SCD) is still a major public health issue with an estimated annual incidence ranging from 184,000 to > 400,000 per year. The ACC/AHA/ESC 2006 guidelines define SCD as “death from an unexpected circulatory arrest, usually due to a cardiac arrhythmia occurring within an hour of the onset of symptoms”. A recent study of sudden cardiac death using multiple sources of ascertainment found that coronary artery disease was present in more than 50% of patients older than 35 years who died suddenly and underwent autopsy. Antiarrhythmic drugs have failed to show any mortality benefit even when compared to placebo or implantable cardiovertor defibrillators (ICDs). While patients with systolic heart failure are at higher risk of dying suddenly, most of the patients experiencing sudden cardiac death have left ventricular ejection fraction (LVEF) > 50%. β-blockers, Angiotensin enzymes (ACE) inhibitors as well as aldosterone antagonists prevent ischemia and remodelling in the left ventricle especially in post myocardial infarction (MI) patients and in patients with systolic heart failure. This article will review the data on the effects of traditional heart failure medications, especially β-blockers, Renin Angiotensin system blockers, as well as Statin therapy on sudden cardiac death in post MI patients and in patients with systolic heart failure.

Renin-angiotensin system inhibitors for prevention of recurrent atrial fibrillation: a meta-analysis

INTRODUCTION

Conflicting results exist now on the clinical utility of renin-angiotensin system (RAS) inhibitors in patients with atrial fibrillation (AF). This study aimed to elaborate the efficacy and safety of RAS blockade on preventing the relapse of AF by a meta-analysis based on randomised controlled trials (RCTs).

METHODS

We searched Medline, ISI web of science and Cochrane databases through Jan 2012. We included RCTs comparing RAS inhibition treatment vs. placebo or alternative therapy after cardioversion of persistent AF or conventional medical therapy for paroxysmal AF and reporting outcome of recurrent AF. Odds ratios (OR) were calculated using a random effects model.

RESULTS

Fifteen trials involving 3972 AF patients were included in the analysis. The pooling analysis showed that RAS inhibitors significantly reduced the recurrence of AF compared with non-RAS inhibitors (OR=0.50, 95% CI: 0.37-0.69, p<0.01), and the beneficial effect was shown consistently both in patients with paroxysmal and in those with persistent AF after cardoversion. However, administration of RAS inhibitors did not provide a greater survival advantage and a lower incidence of adverse effects than the control (OR=1.17, 95% CI, 0.65-2.10, p=0.59; OR=0.94, 95% CI: 0.65-1.35, p=0.73 respectively). In addition, clinical factors potentially affecting AF relapsing had no pronounced impacts on the above clinical outcomes.

CONCLUSIONS

Based on the currently available data, inhibition of RAS is effective, safe and well tolerated for preventing the recurrence of AF.

Effect of renal sympathetic denervation on atrial substrate remodeling in ambulatory canines with prolonged atrial pacing

We have previously demonstrated that catheter-based renal sympathetic denervation (RSD) could suppress atrial fibrillation (AF) in canines with short-time rapid right atrial pacing (RAP). However, the role of renal denervation on atrial remodeling is unclear. The aim of the present study was to explore the long-term effect of RSD on the atrial remodeling during prolonged RAP. Twenty mongrel dogs were implanted with a high-frequency cardiac pacemaker with a transvenous lead inserted into the right atrial appendage. The dogs were divided into three groups: a sham-operated group (n = 6), the chronic RAP (CRAP) group (n = 7), and the CRAP+RSD group (n = 7). In the CRAP+RSD group, a pacemaker was implanted 6 weeks after RSD was performed bilaterally for recovery. RAP was maintained for 5 weeks in CRAP group and CRAP+RSD group. The plasma levels of Angiotensin II and aldosterone were significantly increased in CRAP group compared with sham-operated group, but the increasing trend was inhibited in CRAP+RSD group compared with CRAP group (P<0.05). Similarly, RSD suppressed the increasing trend that prolonged RAP produced in the left atrial levels of ANP, TNF-α and IL-6. Compared with the sham-operated group, the CRAP group had significantly increased levels of caspase-3, bax and Cx40 whereas the level of Bcl-2 decreased (P<0.05). RSD markedly reduced the upregulation of caspase-3, bax and Cx40 and the downregulation of Bcl-2 expression compared with the CRAP group (P<0.05). Picric acid–sirius red staining study suggested that RSD could markedly alleviate the lesion degree of cardic fibrosis induced by CRAP (P<0.05). Immunohistochemistry results showed that the densities of TH- and GAP43- positive nerves were significantly elevated in the CRAP group compared with the sham-operated group, while RSD operation signicantly inhibited the these changes produced by CRAP. These findings suggest that renal denervation could suppress the atrial remodeling after prolonged RAP in ambulatory canines.

Management strategies in atrial fibrillation in patients with heart failure

Atrial fibrillation (AF) and heart failure (HF) frequently occur together, and their coexistence is associated with a poor prognosis. AF and HF share risk factors, but their relationship involves complex hemodynamic, neurohormonal, inflammatory, ultrastructural, and electrophysiologic processes that extend beyond epidemiological associations. The shared mechanisms underlying AF and HF have important implications for the treatment of AF in patients with HF. This article focuses on reviewing contemporary data as it pertains to AF management in patients with HF and provides insight into investigational therapies currently under development.

The Impact of Suppressing the Renin-Angiotensin System on Atrial Fibrillation

Atrial fibrillation is very common in the United States. After a search of Medline, EMBASE, and CINAHL, 4 trials evaluating inhibitors of the renin-angiotensin system were identified for prevention of new-onset atrial fibrillation, facilitation of electrical cardioversion of atrial fibrillation, and prevention of atrial fibrillation recurrence after electrical cardioversion. A meta-analysis was performed using a random-effects model. Use of an angiotensin-converting enzyme (ACE) inhibitor or angiotensin-receptor blocker (ARB) was associated with a reduction in new-onset atrial fibrillation (OR [95% CI] = 0.51 [0.36-0.72]), a lower failure rate of electrical cardioversion of atrial fibrillation (0.47 [0.24-0.92]), and a lower rate of recurrence of atrial fibrillation after electrical cardioversion (0.39 [0.20-0.75]). With the exception of the new-onset atrial fibrillation analysis, these findings were not associated with statistical heterogeneity. These hypothesis-generating data suggest that inhibitors of the renin-angiotensin system may provide benefit across the spectrum of atrial fibrillation.

Irbesartan-mediated AT1 receptor blockade attenuates hyposmotic-induced enhancement of I Ks current and prevents shortening of action potential duration in atrial myocytes

INTRODUCTION

Stretch of the atrial membrane upregulates the slow component of delayed rectifier K(+) current (I(Ks)). Blockade of angiotensin II subtype 1 receptors (AT(1)R) attenuates this increase in I(Ks). The present study aimed to examine the effects of irbesartan, a selective AT(1)R blocker (ABR), on both the enhancement of I(Ks) and the shortening of action potential duration (APD) induced by stretching atrial myocytes for exploring the mechanisms underlying the prevention of atrial fibrillation (AF) by ABR.

METHODS

Hyposmotic solution (Hypo-S) was used to stretch guinea pig atrial myocytes. I(Ks) and APD were recorded using the whole-cell patch-clamp technique.

RESULTS

Irbesartan (1-50 μM) attenuated the Hypo-S-induced increase in I(Ks) and shortening of APD90. Hypo-S increased the I(Ks) by 113.4%, whereas Hypo-S + 1 μM irbesartan and Hypo-S + 50 μM irbesartan increased the I(Ks) by only 74.5% and 70.3%, respectively. In addition, Hypo-S shortened the APD(90) by 19.0%, whereas Hypo-S + 1 μM irbesartan and Hypo-S + 50 μM irbesartan shortened the APD90 by 12.1% and 12.0%, respectively.

CONCLUSION

The actions of irbesartan on electrical changes induced by stretching atrial myocytes are associated with blocking AT(1)R. These actions may be beneficial for treating AF.

Angiotensin receptor blockers and statins could alleviate atrial fibrosis via regulating platelet-derived growth factor/Rac1/nuclear factor-kappa B Axis

AIMS

To investigate whether the administration of renin-angiotensin system (RAS) inhibitors and statins could alleviate atrial fibrosis via platelet-derived growth factor (PDGF)/Rac1 /nuclear factor-kappa B (NF-κB) axis.

METHODS AND RESULTS

In human left atrium, the degree of atrial fibrosis, as well as the expression levels of PDGF, Rac1 and NF-κB increased 1.5 to 2.9 folds in patients with atrial fibrillation compared to that with sinus rhythm, (P<0.0001). There were strongly positive correlations between angiotensin II (Ang II) or procollagen type III-alpha-1 (COL3A1) with PDGF, Rac1, NF-κB, and among PDGF, Rac1 and NF-κB (all P<0.05). At 3 weeks after the transverse aorta constriction (TAC) operation in rat model and with intervention of irbesartan or/and simvastatin, the collagen volume fraction (CVF) and atrial natriuretic peptide (ANP) values respectively increased 6-folds and 3.5-folds in the TAC group compared to SHAM group (P<0.0001), but these levels decreased by 16% to 63% with following drug intervention (all P<0.0001), the combined treatment was the lowest. Accordingly, the expression levels of PDGF (3-folds), Rac1 (1.6-folds), NF-κB (7-folds) and AngII (12-folds) significantly increased in the TAC group compared to the SHAM group, and these levels were also reduced by 25% to 64% with following drug intervention. The highest reduction could be seen after treatment with irbesartan and simvastatin in combination (all P<0.001).There were strongly positive correlations between AngII or CVF with PDGF, Rac1, NF-κB, and among PDGF, Rac1 and NF-κB (all P<0.05).

CONCLUSIONS

Irbesartan or/and simvastatin can improve atrial fibrosis by regulating PDGF/Rac1/NF-κB axis.

Omega-3 Polyunsaturated Fatty Acid Supplementation: Mechanism and Current Evidence in Atrial Fibrillation

Atrial fibrillation (AF) is the most prevalent arrhythmia and is associated with considerable morbidity and mortality. Available pharmacologic antiarrhythmic therapies are often ineffective in preventing the recurrence of AF, possibly because these drugs target a single pathophysiological mechanism. Given their beneficial effects on ventricular arrhythmias, omega-3 polyunsaturated fatty acids (n-3 PUFAs) have recently been investigated as possible candidates in the treatment of supraventricular arrhythmias. In this review, we explore the current understanding of the antiarrhythmic effects attributed to n-3 PUFAs including direct modulation of ionic channels, improvement of membrane fluidity, anti-inflammatory and antifibrotic effects, and modulation of sympatho-vagal balance. We will then focus on the results of epidemiologic studies exploring the associations between nutritional intake of n3 PUFAs and the incidence of AF, and will review the findings of the clinical trials investigating the effects of n-3 PUFAs supplementation in the prophylaxis of AF and in the prevention of its recurrences.

The genetics of atrial fibrillation

PURPOSE OF REVIEW

A substantial genetic contribution to the etiology of atrial fibrillation has emerged in the last decade, and has bolstered links between this arrhythmia and other forms of heart disease. In this article, we will summarize the work that has defined the inherited diathesis toward atrial fibrillation, outline the genetic studies to date, and characterize the roadblocks to a complete mechanistic understanding of this common arrhythmia.

RECENT FINDINGS

Clinical genetic work has demonstrated a large heritable contribution in atrial fibrillation, with studies in lone forms of the arrhythmia suggesting a traditional monogenic syndrome with reduced penetrance. Several Mendelian loci for typical forms of atrial fibrillation have been identified but the genes have not yet been cloned. Rare forms of familial atrial fibrillation are caused by mutations in potassium channel genes, and there are single families with mutations in a nuclear pore and a natriuretic peptide gene, respectively. Common loci with small effects are now being identified in genome-wide association (GWA) studies, including a locus on chromosome 4q25. These loci explain less than 10% of the inherited contribution to the arrhythmia, suggesting there are major contributions that have not yet been uncovered.

SUMMARY

Although great strides have been made in exploring the genetics of atrial fibrillation, the paroxysmal and asymptomatic nature of the phenotype challenges investigators as they seek the mechanistic basis of the arrhythmia.

The role of irbesartan in the treatment of patients with hypertension: a comprehensive and practical review

Irbesartan is an orally active angiotensin II type 1 receptor antagonist (angiotensin receptor blocker [ARB]) whose pharmacological profile differs significantly from those of many other compounds of the same class. In particular, according to its pharmacokinetic and pharmacodynamic profile, irbesartan has a high bioavailability, a long duration of action and a small potential for pharmacological interactions due to the nature of the enzymatic pathway involved in its metabolic process. Morbidity data with irbesartan have been mainly accumulated in patients with renal impairment where the drug has demonstrated the most remarkable evidence of efficacy among the ARBs class, regardless of the stage of the renal disease (from early to late) and the length of the observational period. The efficacy of irbesartan has also been demonstrated in patients with left ventricular hypertrophy and congestive heart failure. The drug is indicated for the treatment of hypertension and renal impairment in patients with type 2 diabetes mellitus (T2D) and hypertension, and its tolerability and safety profile have been extensively investigated and reported to be similar to placebo. From the pharmacoeconomic point of view, treating patients with T2D, hypertension and overt nephropathy using irbesartan was both a cost- and life-saving procedure compared with the use of amlodipine and standard antihypertensive treatment in an Italian setting. The role of irbesartan in the management of hypertension with or without T2D and renal impairment is clearly recognized by national and international guidelines and largely acknowledged by the medical community according to the efficacy of the drug in the prevention of cardiovascular risk in addition to and beyond kidney prevention.

Adjunctive Pharmacotherapy for Elective Direct Current Cardioversion in Patients With Atrial Fibrillation

BACKGROUND

Direct current cardioversion (DCCV) can restore sinus rhythm in patients with atrial fibrillation (AF), but the long term efficacy is poor. Pharmacological therapies may improve the initial success of the procedure, but whether long term maintenance of sinus rhythm can be improved is unclear. The aim of this study was to evaluate which pharmacotherapies, including antiarrhythmic and renin-angiotensin-aldosterone system (RAAS) inhibiting drugs, most successfully promotes sinus rhythm after elective DCCV in unselected patients with atrial fibrillation.

METHODS

A retrospective cohort was to study of AF patients attending or DCCV between Jan 2010 and Feb 2012. The data were analysed using multivariate logistical regression models. Initial success of DCCV was the dependent variable in the first analysis. Maintenance of sinus rhythm at follow up was the dependent variable in the second analysis.

RESULTS

One hundred and thirty patients were included in the first analysis, and 71 patients were included in the second analysis. The only association observed was a positive association between flecainide and an increased odds of maintaining sinus rhythm at follow up (OR 2.14, SE ± 0.93, P = 0.02) .Other antiarrhythmic drugs and RAAS inhibiting drugs had no association with an increased odds of successful DCCV or maintenance of sinus rhythm thereafter.

CONCLUSIONS

This is the first study to demonstrate an association between flecainide and a increased odds of maintaining sinus rhythm after DCCV in the long term. This warrants further research, and should be taken into account when choosing adjunctive antiarrhythmic therapy for elective DCCV for AF.

Short-term versus long-term antiarrhythmic drug treatment after cardioversion of atrial fibrillation (Flec-SL): a prospective, randomised, open-label, blinded endpoint assessment trial

BACKGROUND

Antiarrhythmic drugs prolong the atrial action potential and refractory period, and thereby prevent recurrent atrial fibrillation after cardioversion. The atrial action potential normalises after 2-4 weeks of sinus rhythm, suggesting that antiarrhythmic drugs might not be needed beyond that period. Therefore, we investigated whether short-term antiarrhythmic drug treatment after cardioversion is non-inferior to long-term treatment.

METHODS

We enrolled patients in a prospective, randomised, open-label, blinded endpoint assessment trial between May 4, 2007, and March 12, 2010, at 44 centres in Germany. Eligible patients were adults with persistent atrial fibrillation undergoing planned cardioversion. After successful cardioversion, patients were randomly assigned in permuted blocks of six per centre to: no antiarrhythmic drug treatment (control); treatment with flecainide (200-300 mg per day) for 4 weeks (short-term treatment); or flecainide for 6 months (long-term treatment). The primary endpoint was time to persistent atrial fibrillation or death. Patients and clinicians were unmasked to group assignment and treatment. The primary outcome was assessed in a core laboratory, members of which were masked to treatment group. Patients were monitored for 6 months by daily telemetric electrocardiograph (ECG) and centrally adjudicated Holter ECG recordings whenever atrial fibrillation was noted in two consecutive ECGs. Analyses were per protocol. This trial is registered, number ISRCTN62728742.

FINDINGS

After assay sensitivity was established with 4-week follow-up data from 242 patients showing that flecainide was superior to no treatment (Kaplan-Meier survival 70·2%vs 52·5%; p=0·0160), the trial continued to compare short-term versus long-term treatment. The primary outcome occurred in 120 (46%) of 261 patients receiving short-term treatment and in 103 (39%) of 263 patients receiving long-term treatment (event-free survival 48·4% [95% CI 41·9-55·0] vs 56·4% [49·1-63·6]; Kaplan-Meier estimate of difference 7·9% [-1·9 to 17·7]; p=0·2081 for non-inferiority; margin prespecified at 12%). In a post-hoc landmark analysis of patients who had not reached the primary endpoint in the first month, long-term treatment was superior to short-term treatment (Kaplan-Meier estimate of difference 14·3% [5·1-23·6]; hazard ratio 0·31 [0·18-0·56]; p=0·0001).

INTERPRETATION

Short-term antiarrhythmic drug treatment after cardioversion is less effective than is long-term treatment, but can prevent most recurrences of atrial fibrillation.

FUNDING

The German Federal Ministry of Education and Research, Deutsche Forschungsgemeinschaft, 3M Medica, and MEDA Pharmaceuticals.

Hypertension and atrial fibrillation: diagnostic approach, prevention and treatment. Position paper of the Working Group 'Hypertension Arrhythmias and Thrombosis' of the European Society of Hypertension

Hypertension is the most common cardiovascular disorder and atrial fibrillation is the most common clinically significant arrhythmia. Both these conditions frequently coexist and their prevalence increases rapidly with aging. There are different risk factors and clinical conditions predisposing to the development of atrial fibrillation, but due its high prevalence, hypertension is still the main risk factor for the development of atrial fibrillation. Several pathophysiologic mechanisms (such as structural changes, neurohormonal activation, fibrosis, atherosclerosis, etc.) have been advocated to explain the onset of atrial fibrillation. The presence of atrial fibrillation per se increases the risk of stroke but its coexistence with high blood pressure leads to an abrupt increase of cardiovascular complications. Different risk models are available for the risk stratification and the prevention of thromboembolism in patients with atrial fibrillation. In all of them hypertension is present and is an important risk factor. Antihypertensive treatment may contribute to reduce this risk, and it seems some classes are superior to others in the prevention of new-onset atrial fibrillation and prevention of stroke. Antithrombotic treatment with warfarin is effective in the prevention of thromboembolic events, although quite recently, new classes of anticoagulants that do not require international normalized ratio monitoring have been introduced with promising results.

Effect of telmisartan on paroxysmal atrial fibrillation recurrence in hypertensive patients with normal or increased left atrial size

BACKGROUND

Hypertension is the most prevalent and potentially modifiable risk factor for atrial fibrillation (AF). In a previous secondary prevention study, the authors observed that the angiotensin II receptor blocker telmisartan was more effective than the calcium channel blocker amlodipine in preventing AF relapse in hypertensive patients with normal atrial size.

HYPOTHESIS

Telmisartan may be more effective than amlodipine in preventing AF recurrence in hypertensive patients with paroxysmal AF and normal or increased left atrial dimension (LAD).

METHODS

The authors assigned 378 mild hypertensive outpatients in sinus rhythm, but with ≥2 episodes of AF in the previous 6 months, to 1 of 2 groups. Group 1 comprised patients with LAD <40 mm in females and <45 mm in males. Group 2 comprised patients with LAD >40 mm and <45 mm in females and >45 mm and <50 mm in males. In both groups, patients were randomly treated with telmisartan or amlodipine for 1 year.

RESULTS

Systolic and diastolic blood pressure were similarly reduced by telmisartan and amlodipine in both groups. The AF recurrence rate was significantly lower in the telmisartan-treated patients than in the amlodipine-treated patients in both group 1 (12 vs 39, P < 0.01) and group 2 (40 vs 59, P < 0.05). Under telmisartan, the AF recurrence rate was significantly lower in group 1 than in group 2 (12.9% vs 42.1%, P < 0.05). Time to a first AF relapse was significantly longer with telmisartan than with amlodipine in both group 1 (176 ± 94 days vs 74 ± 61 days, P < 0.05) and group 2 (119 ± 65 days vs 38 ± 35 days, P < 0.05).

CONCLUSIONS

Telmisartan was more effective than amlodipine in preventing AF recurrences in hypertensive patients with paroxysmal AF.

The role of the renin-angiotensin system blocking in the management of atrial fibrillation

OBJECTIVE

To review current available evidence for the role of renin-angiotensin system blockade in the management of atrial fibrillation.

METHOD

We conducted a PubMed and Medline literature search (January 1980 through July 2011) to identify all clinical trials published in English concerning the use of angiotensin converting enzyme inhibitors or angiotensin II receptor blockers for primary and secondary prevention of atrial fibrillation. We also discussed renin-angiotensin system and its effects on cellular electrophysiology.

CONCLUSION

The evidence from the current studies discussed does not provide a firm definitive indication for the use of angiotensin converting enzyme inhibitors or angiotensin II receptor blockers in the primary or secondary prevention of atrial fibrillation. Nevertheless, modest benefits were observed in patients with left ventricular dysfunction. In view of the possible benefits and the low incidence of side-effects with angiotensin converting enzyme inhibitors and angiotensin II receptor blockers, they can be given to patients with recurrent AF, specifically those with hypertension, heart failure and diabetes mellitus.