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

High-sensitivity C-reactive protein is predictive of successful cardioversion for atrial fibrillation and maintenance of sinus rhythm after conversion

BACKGROUND

Cardioversion for atrial fibrillation (AF) is the most effective treatment for the restoration of sinus rhythm (SR). Recently, an elevated level of hs-CRP has been shown to be associated with AF burden, suggesting that inflammation increases the propensity for persistence of AF. We examined whether the level of high-sensitivity C-reactive protein (hs-CRP) was predictive of the outcome of cardioversion for AF.

METHODS AND RESULTS

One hundred and six patients with a history of symptomatic AF lasting > or =1 day (age 63+/-14 years, mean+/-S.D.) underwent cardioversion. Echocardiography and hs-CRP assay were performed immediately prior to cardioversion. SR was restored in 84 patients (79%). By using selected cutoff values, multiple discriminant analysis revealed significant associations between successful cardioversion and a shorter duration of AF (AF duration< or =36 days, odds ratio (OR), 0.98; 95% confidence interval (CI), 0.97-0.99), smaller left atrial diameter (left atrial diameter< or =40 mm, OR 0.82, 95% CI 0.71-0.94), better-preserved left ventricular ejection fraction (left ventricular ejection fraction> or =60%, OR 0.92, 95% CI 0.86-0.99), and lower hs-CRP level (hs-CRP< or =0.12 mg/dL, OR 0.33, 95% CI 0.21-0.51). During a follow-up period of 140+/-144 days, AF recurred in 64 patients (76%). By using a cutoff value of hs-CRP> or =0.06 mg/dL, Cox proportional-hazards regression model found that only hs-CRP level was an independent predictor of AF recurrence (OR 5.30, 95% CI 2.46-11.5) after adjustment for coexisting cardiovascular risks. When patients were divided by the hs-CRP level of 0.06 mg/dL, percentage of maintenance of SR below and above the cutoff was 53% and 4%, respectively (log-rank test, p<0.0001).

CONCLUSIONS

hs-CRP level determined prior to cardioversion represents an independent predictor of both successful cardioversion for AF and the maintenance of SR after conversion.

Role of angiotensin receptor blockers in the prevention and treatment of arrhythmias

The renin-angiotensin system is a key regulatory system that is activated in many forms of cardiovascular disease. It is well established that angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) are important therapeutic agents in the treatment of hypertension, myocardial infarction, and congestive heart failure. More recent research has suggested that renin-angiotensin system activation may also play a critical role in the genesis of atrial and ventricular arrhythmias. The possible role of renin-angiotensin system activation in arrhythmogenesis suggests that ACE inhibitors and ARBs may be important therapeutic agents in the prevention and treatment of arrhythmias. This review summarizes the current evidence for the use of ARBs in the treatment of atrial and ventricular arrhythmias.

Potential clinical correlates and risk factors for interatrial block

BACKGROUND

Interatrial block (IAB; P wave > or =110 ms) denotes a conduction delay between the atria, is strongly associated with atrial tachyarrhythmias, left atrial enlargement, left atrial electromechanical dysfunction, and is a risk for embolism. Despite this, potential risk factors for IAB have not been clearly defined.

METHODS

Patients admitted via the Emergency Department for nonacute medical reasons to the nontelemetry general medical floors of a tertiary care general hospital from October to November 2004 were screened for sinus rhythm on electrocardiograms. Four hundred and four patients who met our criteria were then evaluated for IAB on respective electrocardiograms. All patients were subsequently compared for common diseases as well as coronary artery disease (CAD) risk factors and divided into two groups, those with IAB and those without (control). Mean age +/- standard deviation, odds ratios (ORs), 95% confidence intervals (CIs), r values, and p values were calculated. p values <0.05 were considered statistically significant.

RESULTS

From the sample (n = 404), 182 patients had IAB (45%; mean age 64.32 +/- 19.27 years; males 51.6%) while 222 did not (control). CAD (OR 3.150, 95% CI 2.05-4.83; p < 0.001, r = 0.3), hypertension (OR 2.918, 95% CI 1.85-4.60; p < 0.001, r = 0.2), diabetes mellitus (OR 2.542, 95% CI 1.62-3.97; p < 0.001, r = 0.1), and hypercholesterolemia (OR 1.823, 95% CI 1.22-2.74; p = 0.004, r = 0.2) were significant risk factors and correlates for IAB. Multivariate analysis using stepwise linear regression revealed these factors as direct correlates of IAB.

CONCLUSION

CAD, hypertension, diabetes mellitus and hypercholesterolemia appear to be risk factors for IAB in general hospital patients admitted for nonacute reasons. Considering the known sequelae of IAB, awareness of its associations with such risk factors could be important for patient risk stratification.

Atrial fibrillation increases production of superoxide by the left atrium and left atrial appendage: role of the NADPH and xanthine oxidases

BACKGROUND

Atrial fibrillation (AF) is associated with an increased risk of stroke due almost exclusively to emboli from left atrial appendage (LAA) thrombi. Recently, we reported that AF was associated with endocardial dysfunction, limited to the left atrium (LA) and LAA and manifest as reduced nitric oxide (NO*) production and increased expression of plasminogen activator inhibitor-1. We hypothesized that reduced LAA NO* levels observed in AF may be associated with increased superoxide (O2*-) production.

METHODS AND RESULTS

After a week of AF induced by rapid atrial pacing in pigs, O2*- production from acutely isolated heart tissue was measured by 2 independent techniques, electron spin resonance and superoxide dismutase-inhibitable cytochrome C reduction assays. Compared with control animals with equivalent ventricular heart rates, basal O2*- production was increased 2.7-fold (P<0.01) and 3.0-fold (P<0.02) in the LA and LAA, respectively. A similar 3.0-fold (P<0.01) increase in LAA O2*- production was observed using a cytochrome C reduction assay. The increases could not be explained by changes in atrial total superoxide dismutase activity. Addition of either apocyanin or oxypurinol reduced LAA O2*-, implying that NADPH and xanthine oxidases both contributed to increased O2*- production in AF. Enzyme assays of atrial tissue homogenates confirmed increases in LAA NAD(P)H oxidase (P=0.04) and xanthine oxidase (P=0.01) activities. Although there were no changes in expression of the NADPH oxidase subunits, the increase in superoxide production was accompanied by an increase in GTP-loaded Rac1, an activator of the NADPH oxidase.

CONCLUSIONS

AF increased O2*- production in both the LA and LAA. Increased NAD(P)H oxidase and xanthine oxidase activities contributed to the observed increase in LAA O2*- production. This increase in O2*- and its reactive metabolites may contribute to the pathological consequences of AF such as thrombosis, inflammation, and tissue remodeling.

Prevalence and predictors of electrical storm in patients with implantable cardioverter-defibrillator

Identifying predictors of electrical storm in patients with implantable cardioverter-defibrillators (ICDs) could help identify those at risk and reduce the incidence of this emergency situation, which has a detrimental effect on mortality and morbidity in patients with ICDs. This retrospective study sought to determine the prevalence and predictors of electrical storm in patients with ICDs. One hundred sixty-two patients (126 men; mean age 58 +/- 13 years) who received ICDs from January 2001 to January 2005 were included in the study. Clinical, electrocardiographic, and ICD stored data and electrograms were collected and analyzed. Twenty-two patients (14%) developed electrical storm during a mean follow-up of 14.3 +/- 10 months. Using Cox multiple regression analysis, it was found that an ejection fraction <25% (p = 0.007), QRS width > or =120 ms (p = 0.002), and a lack of adjunctive angiotensin-converting enzyme inhibitor and beta-blocker therapy (both p < 0.001) were correlated with a greater probability of electrical storm. Adjunctive amiodarone and digoxin therapy, indication of ICD implantation, and age were not correlated with the occurrence of electrical storm during follow-up (all p = NS). In conclusion, electrical storm is not uncommon in patients with ICDs. Optimum medical therapy with beta blockers and angiotensin-converting enzyme inhibitors could reduce the occurrence of electrical storm, and this especially should be considered in those at greater risk for this complication (i.e., those with left ventricular ejection fractions <25% and QRS widths > or =120 ms).

Inter-atrial conduction time shortens after blood pressure control in hypertensive patients with left ventricular hypertrophy

Assuming that blood pressure control could induce a shortening of the inter-atrial conduction time and prevent atrial fibrillation occurrence, we studied the inter-atrial conduction time in hypertensive patients with left ventricular hypertrophy.

METHODS

Sixty-eight (26 male) 58.34+/-8.08-year-old patient participated in the study. All were in sinus rhythm and had abnormal blood pressure (163+/-18/95+/-9 mm Hg). Their cardiac mass index was increased (151+/-43 g/m(2) SC) and their left atrial dimension was normal (3.67+/-0.54 cm). The inter-atrial conduction time was measured in the echocardiogram from the beginning of the electrocardiographic P wave to the beginning of the A wave in the mitral Doppler signal and was corrected for heart rate. Heart rhythm disturbances were monitored clinically and by means of a Holter. Most patients were treated with angiotensin antagonists.

RESULTS

It was found that arterial blood pressure decreased significantly after treatment and that the P-A interval was significantly reduced (71.4+/-14.5 vs. 63.9+/-11.5 ms). During the follow-up, no patient complained of arrhythmia symptoms or exhibited atrial fibrillation in the Holter recording.

CONCLUSION

In this selected group of patients with hypertensive heart disease (left ventricular hypertrophy), an effective blood pressure control was accompanied by a significant decrease in the inter-atrial conduction time. It is possible that these effects prevent atrial fibrillation.

Angiotensin II and angiotensin II receptor blocker modulate the arrhythmogenic activity of pulmonary veins

Angiotensin II receptor blockers (AIIRBs) have been shown to prevent atrial fibrillation. The pulmonary veins (PVs) are the most important focus for the generation of atrial fibrillation. The aim of this study was to evaluate whether angiotensin II or AIIRB may change the arrhythmogenic activity of the PVs. Conventional microelectrodes and whole-cell patch clamps were used to investigate the action potentials (APs) and ionic currents in isolated rabbit PV tissue and single cardiomyocytes before and after administering angiotensin II or losartan (AIIRB). In the tissue preparations, angiotensin II induced delayed after-depolarizations (1, 10, and 100 nM) and accelerated the automatic rhythm (10 and 100 nM). Angiotensin II (100 nM) prolonged the AP duration and increased the contractile force (10 and 100 nM). Losartan (1 and 10 microM) inhibited the automatic rhythm. Losartan (10 microM) prolonged the AP duration and reduced the contractile force (1 and 10 microM). Angiotensin II reduced the transient outward potassium current (I(to)) but increased the L-type calcium, delayed rectifier potassium (I(K)), transient inward (I(ti)), pacemaker, and Na(+)-Ca(2+) exchanger (NCX) currents in the PV cardiomyocytes. Losartan decreased the I(to), I(K), I(ti), and NCX currents. In conclusion, angiotensin II and AIIRB modulate the PV electrical activity, which may play a role in the pathophysiology of atrial fibrillation.

Randomized Crossover Study of the Long-Term Effects of Pilsicainide and Cibenzoline in Preventing Recurrence of Symptomatic Paroxysmal Atrial Fibrillation Influence of the Duration of Arrhythmia Before Therapy

BACKGROUND

There is little information on the selection of antiarrhythmic agents for long-term prevention of paroxysmal atrial fibrillation (PAF). In the present study the preventive effects of pilsicainide (Pil) and cibenzoline (Cib) were compared in patients with PAF that was defibrillated at <48 h or >or=48 h after onset.

METHODS AND RESULTS

A total of 60 patients (45 men, 15 women, mean age 66+/-10 years) were divided into 2 groups: Group I consisted of 22 patients in whom atrial fibrillation (AF) lasted for <48 h before cardioversion and Group II consisted of 38 patients in whom AF lasted for >or=48 h. A randomized, crossover protocol of treatment with Pil (150 mg/day) and Cib (300 mg/day) was used. Mean follow-up was 35+/-18 months. In Group I, the mean duration of maintenance of sinus rhythm was 12.3+/-2.9 months in patients treated with Pil, compared with 12.9+/-2.5 months in those givem Cib (p=NS between 2 groups). Actuarial event-free rates at 1, 3, 6, 12 months were 82%, 68%, 59% and 41%, respectively, in patients treated with Pil, and 91%, 77%, 68% and 50%, respectively, in those givenh Cib (p=NS between 2 groups). In Group II, the mean duration of maintenance of sinus rhythm was 1.6+/-0.5 months in patients treated with Pil, compared with 5.9+/-1.7 months in those given Cib (p<0.01). Actuarial event-free rates at 1, 3, 6, 12 months were 45%, 18%, 8% and 3%, respectively, in patients treated with Pil, and 63%, 45%, 29% and 16%, respectively, in those given Cib (p<0.05, at 12 months).

CONCLUSIONS

Prolonged tachycardia (>or=48 h) in patients with PAF seems to cause electrical remodeling. Cib, a multichannel blocker, is considered to be more effective in preventing the recurrence of PAF in the electrically remodeled atria than Pil, a pure sodium-channel blocker.

Randomized Study of Angiotensin II Type 1 Receptor Blocker vs Dihydropiridine Calcium Antagonist for the Treatment of Paroxysmal Atrial Fibrillation in Patients With Hypertension The J-RHYTHM II Study Design for the Investigation of Upstream Therapy for Atrial Fibrillation

BACKGROUND

Mega trials of rhythm vs rate control could not demonstrate the usefulness of available antiarrhythmic drugs, so a more effective and safer therapy for atrial fibrillation (AF) is now required. One candidate is the so-called "upstream therapy", which refers to the blockade of upstream modifying elements (renin - angiotensin system, cathecholamines, oxidative stress etc) that contribute to the arrhythmogenic substrate.

METHODS AND RESULTS

The Japanese Rhythm Management Trial II for Atrial Fibrillation (J-RHYTHM II study) is a randomized comparative evaluation of an angiotensin II type 1 blocker (candesartan) and a dihydropiridine calcium blocker (amlodipine), both combined with antithrombotic therapy, as an antiarrhythmic therapy for the treatment of paroxysmal AF (PAF) associated with hypertension. To test the usefulness of this therapy, this study will reveal the recurrence rate of asymptomatic as well as symptomatic PAF during 1-year of treatment with candesartan or amlodipine, using daily transtelephonic monitoring.

CONCLUSIONS

The J-RHYTHM II study will follow 400 patients with PAF and hypertension who were treated at approximately 50 sites throughout Japan, and will provide clinically important information.

Losartan and Prevention of Atrial Fibrillation Recurrence in Hypertensive Patients

The aim of the study was to evaluate the effect of losartan as compared with amlodipine, both associated with amiodarone, in preventing the recurrence of atrial fibrillation (AF) in hypertensive patients with a history of recent paroxysmal atrial fibrillation. Two hundred and fifty mild hypertensive (SBP > 140 mm Hg and/or DBP > 90 < 100 mm Hg) outpatients in sinus rhythm but with at least two ECG-documented episodes of symptomatic atrial fibrillation in the previous 6 months and in treatment with amiodarone were randomized to losartan or amlodipine and were followed up for 1 year. Clinic blood pressure (BP) and a 24-hour ECG was evaluated every month; the patients were asked to report any episode of symptomatic atrial fibrillation and to perform an ECG as early as possible. Two hundred and thirteen patients completed the study, 107 in the losartan group and 106 in the amlodipine group. After 12 months the SBP/DBP mean values were significantly reduced by both losartan (from 151.4/95.6 to 135.5/83.7 mm Hg, P < 0.001 versus baseline) and amlodipine (from 152.3/96.5 to 135.2/83.4 mm Hg, P < 0.001 versus baseline), with no difference between the two treatments. At least one ECG-documented episode of atrial fibrillation was reported in 13% of the patients treated with losartan and in 39% of the patients treated with amlodipine. The use of losartan in combination with amiodarone seems more effective than amlodipine/amiodarone combination in preventing new episodes of atrial fibrillation in hypertensive patients with recurrent atrial fibrillation. This might be related to possible favorable impact of angiotensin II receptor blockers (ARB) on the atrial electrical and structural remodeling in this type of patients.

Temas de actualidad 2005: electrofisiología y arritmias

Cardiac electrophysiology laboratories deal with a wide range of pathological conditions, diagnostic techniques, and treatments. Since a huge quantity of material has been published in recent months, this article will be limited to discussion of the most significant developments in the prognostic evaluation of arrhythmias, hereditary disease, syncope, atrial fibrillation, implantable cardioverter-defibrillators, cardiac resynchronization therapy, and catheter ablation. Even within these areas, discussion will be restricted to specific concrete topics and to a limited number of publications that were judged to have important implications for clinical practice. Our principal aim was to provide clinical cardiologists with an overview of the latest developments in cardiac electrophysiology.

Atrial Fibrillation and Congestive Heart Failure: Risk Factors, Mechanisms, and Treatment

Atrial fibrillation (AF) and congestive heart failure (CHF) are commonly encountered together, and either condition predisposes to the other. Risk factors for AF and CHF include age, hypertension, valve disease, and myocardial infarction, as well as a variety of medical conditions and genetic variants. Congestive heart failure and AF share common mechanisms, including myocardial fibrosis and dysregulation of intracellular calcium and neuroendocrine function. Pharmacological treatments including beta-blockers, digoxin, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers can be useful in treating both of these conditions. Antiarrhythmic medications intended to achieve and maintain sinus rhythm may be beneficial in some patients with AF and CHF. Advances in pacemaker and defibrillator therapy, including cardiac resynchronization therapy, may also benefit patients with AF and CHF. Surgical and catheter-based ablation therapy can restore sinus rhythm in patients with AF, with proven benefit in patients with concommitant CHF. Investigational biologic therapy, including cell and gene based therapy, offers promise for the future of reversing the pathophysiological mechanisms that underlie AF and CHF.

Atrial stunning as predictor of early relapse into atrial fibrillation after cardioversion

Although the high rate of success after cardioversion, less than 50% of patients maintain sinus rhythm for the first year. In view for the high percentage of relapse into atrial fibrillation, it is interesting to analyze the relationship between atrial stunning after cardioversion and relapse into atrial fibrillation. Thus, we evaluated 101 patients with atrial fibrillation and successful cardioversion. Atrial mechanical function was assessed by measures of transmitral peak A wave velocity, determined before and weekly after cardioversion during 1 month. Fifty-five percent of patient relapse into atrial fibrillation during follow-up. No significant differences were found in clinical and echocardiographic variables between the group with and without relapse. However, the group of patients who relapsed into atrial fibrillation showed a lower peak A wave velocity immediately after cardioversion than patients who maintain in sinus rhythm at month (0.44+/-0.27 vs. 0.60+/-0.38 m/s p<0.01). Impaired atrial function improves during the first 14 days after cardioversion.

Spironolactone and its main metabolite canrenoic acid block hKv1.5, Kv4.3 and Kv7.1 + minK channels

Both spironolactone (SP) and its main metabolite, canrenoic acid (CA), prolong cardiac action potential duration and decrease the Kv11.1 (HERG) current. We examined the effects of SP and CA on cardiac hKv1.5, Kv4.3 and Kv7.1+minK channels that generate the human I(Kur), I(to1) and I(Ks), which contribute to the control of human cardiac action potential duration.hKv1.5 currents were recorded in stably transfected mouse fibroblasts and Kv4.3 and Kv7.1 + minK in transiently transfected Chinese hamster ovary cells using the whole-cell patch clamp. SP (1 microM) and CA (1 nM) inhibited hKv1.5 currents by 23.2 +/- 3.2 and 18.9 +/- 2.7%, respectively, shifted the midpoint of the activation curve to more negative potentials and delayed the time course of tail deactivation.SP (1 microM) and CA (1 nM) inhibited the total charge crossing the membrane through Kv4.3 channels at +50 mV by 27.1 +/- 6.4 and 27.4 +/- 5.7%, respectively, and accelerated the time course of current decay. CA, but not SP, shifted the inactivation curve to more hyperpolarised potentials (V(h)-37.0 +/- 1.8 vs -40.8 +/- 1.6 mV, n = 10, P < 0.05).SP (10 microM) and CA (1 nM) also inhibited Kv7.1 + minK currents by 38.6 +/- 2.3 and 22.1 +/- 1.4%, respectively, without modifying the voltage dependence of channel activation. SP, but not CA, slowed the time course of tail current decay.CA (1 nM) inhibited the I(Kur) (29.2 +/- 5.5%) and the I(to1) (16.1 +/- 3.9%) recorded in mouse ventricular myocytes and the I(K) (21.8 +/- 6.9%) recorded in guinea-pig ventricular myocytes.A mathematical model of human atrial action potentials demonstrated that K(+) blocking effects of CA resulted in a lengthening of action potential duration, both in normal and atrial fibrillation simulated conditions. The results demonstrated that both SP and CA directly block hKv1.5, Kv4.3 and Kv7.1 + minK channels, CA being more potent for these effects. Since peak free plasma concentrations of CA ranged between 3 and 16 nM, these results indicated that blockade of these human cardiac K(+) channels can be observed after administration of therapeutic doses of SP. Blockade of these cardiac K(+) currents, together with the antagonism of the aldosterone proarrhythmic effects produced by SP, might be highly desirable for the treatment of supraventricular arrhythmias.

Role of angiotensin system and effects of its inhibition in atrial fibrillation: clinical and experimental evidence

Atrial fibrillation (AF) is a common arrhythmia that is difficult to treat. Anti-arrhythmic drug therapy, to maintain sinus-rhythm, is limited by inadequate efficacy and potentially serious adverse effects. There is increasing interest in novel therapeutic approaches that target AF-substrate development. Recent trials suggest that angiotensin converting-enzyme (ACE)-inhibitors and angiotensin-receptor blockers (ARBs) may be useful, particularly in patients with left ventricular hypertrophy or failure. The clinical potential and mechanisms of this approach are under active investigation. Angiotensin-II is involved in remodelling and may have direct electrophysiological actions. Experimental studies show protection from atrial structural and possibly electrical remodelling with ACE-inhibitors and ARBs, as well as potential effects on cardiac ion-channels. This article reviews information pertaining to the clinical use and mechanism of action of ACE-inhibitors and ARBs in AF. A lack of prospective randomized double-blind trials data limits their application in AF patients without another indication for their use, but studies under way may alter this in the near future. This exciting field of investigation may lead to significant improvements in therapeutic options for AF patients.

Is atrial fibrillation an inflammatory disorder?

There is mounting evidence to support the influence of inflammation in the pathogenesis of atrial fibrillation (AF). Indeed, AF is associated with increased levels of known inflammatory markers, even after adjustment for confounding factors. The renin-angiotensin-aldosterone system (RAAS) appears to play a key role in this process. Atrial biopsies from patients with AF have also confirmed the presence of inflammation. Furthermore, there is preliminary evidence to support a number of drug therapies that have the potential to reduce the clinical burden of AF. In this review, we present an overview of the evidence supporting a link between inflammation and AF, and some of the drug therapies, such as the angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, steroids, fish oils, and vitamin C, that might be efficacious in the prevention of AF by modulating inflammatory pathways.

Reduced apelin levels in lone atrial fibrillation

AIMS

Apelin is an endogenous peptide hormone that appears to have a physiological role in counter-regulation of the angiotensin and vasopressin systems. This peptide has been reported to be down-regulated in subjects with acute heart failure, but has not been studied in other cardiovascular conditions. We studied apelin levels in 73 subjects with lone atrial fibrillation (AF).

METHODS AND RESULTS

Study subjects had electrocardiographic evidence of paroxysmal or chronic AF and a structurally normal heart on echocardiography. Subjects were excluded if they had a history of coronary artery disease, rheumatic heart disease, cardiomyopathy, significant valvular disease, hyperthyroidism, or antecedent hypertension. Controls were recruited from a healthy outpatient population. Plasma apelin levels were determined using a commercially available immunoassay. Seventy-three subjects with lone AF and 73 healthy controls were enrolled and studied. Mean levels of apelin were significantly lower in subjects with lone AF when compared with controls (307 vs. 648 pg/mL, P<0.00005).

CONCLUSION

Reduced apelin levels were observed in this homogenous population of lone AF subjects and may represent an underlying diathesis predisposing to this common arrhythmia.

New Antiarrhythmic Drugs for Prevention of Atrial Fibrillation

Enhanced understanding of the mechanisms underlying atrial fibrillation (AF) and advent of catheter-based therapy for AF has altered the approach to patients with this most common arrhythmia. However, despite the success of aggressive procedural techniques, pharmacologic therapy remains the first-line and mainstay approach in the treatment of AF. This review of new antiarrhythmic drug (AAD) therapy for AF provides an in-depth overview of recently available classic and new investigational drugs being considered for AF treatment. Currently available AADs are associated with less than satisfactory efficacy in preventing AF and a significant side effect profile, including ventricular proarrhythmia. Recent investigations have focused on development of new AADs that, hopefully, will be more effective and safer even in patients with structural heart disease. These new AADs include selective multi-ion channel and atrial specific blockers and agents that target the underlying etiologies and substrate alterations that lead to AF. Included among the latter new category are agents that suppress activation of the renin-angiotensin-aldosterone system or inflammation, which represent novel targets for drug therapy for AF. Finally, new selective A1 adenosine receptor agonists may offer the possibility of more specific and successful ventricular rate control during AF. There is considerable hope and interest that improved understanding of AF mechanisms ultimately will result in more effective and less dangerous pharmacologic therapy becoming available in the future.

Drug therapy for atrial fibrillation: where do we go from here?

Atrial fibrillation, the most common cardiac arrhythmia requiring medical attention, has effects that range from mild symptoms to devastating stroke. Although treatments have evolved since the foxglove plant (later identified as containing digitalis) was first administered to slow the heart rate, satisfactory drug therapy has not been developed. In this review we describe present-day medical options and developments of future therapies to treat atrial fibrillation and maintain normal sinus rhythm.

Electrical and Structural Remodeling: Role in the Genesis and Maintenance of Atrial Fibrillation

Atrial fibrillation (AF) and congestive heart failure (CHF) are 2 frequently encountered conditions in clinical practice. Both lead to changes in atrial function and structure, an array of processes known as atrial remodeling. This review provides an overview of ionic, electrical, contractile, neurohumoral, and structural atrial changes responsible for initiation and maintenance of AF. In the last decade, many studies have evaluated atrial remodeling due to AF or CHF. Both conditions often coexist, which makes it difficult to distinguish the contribution of each. Because of atrial stretch in the setting of hypertension or CHF, atrial remodeling frequently occurs long before AF arises. Alternatively, AF may lead to electrical remodeling, that is, shortening of refractoriness due to the high atrial rate itself. In many experimental AF or rapid atrial pacing studies, the ventricular rate was uncontrolled. In those studies, atrial stretch due to CHF may have interfered with the high atrial rate to produce a mixed type of electrical and structural remodeling. Other studies have dissected the individual role of AF or atrial tachycardia from the role CHF plays in atrial remodeling. Atrial fibrillation itself does not lead to structural remodeling, whereas this is frequently produced by hypertension or CHF, even in the absence of AF. Primary and secondary prevention programs should tailor treatment to the various types of remodeling.

Targeted pharmacological reversal of electrical remodeling after cardioversion--rationale and design of the Flecainide Short-Long (Flec-SL) trial

Persistent atrial fibrillation (AF) causes relevant mortality and cardiovascular and noncardiovascular morbidity. Therefore, maintenance of sinus rhythm is an important clinical goal, especially when the patient is symptomatic, despite the fact that current treatment strategies are not sufficient to completely prevent recurrent AF. In addition to underlying atrial disease that predisposes to AF, AF in itself induces structural and electrical adaptations ("electrical remodeling" and "structural remodeling"). Underlying disease processes and parts of structural remodeling are not always reversible. Electrical remodeling, in contrast, is reversed by a few weeks of maintenance of sinus rhythm under experimental conditions. This corresponds to the period when most of the recurrent episodes of AF occur after cardioversion. Antiarrhythmic drugs that prolong the atrial action potential can assist in the prevention of recurrent AF by promoting the reversal of electrical remodeling. Such drugs, which are currently used over long periods after cardioversion, may only be needed until the physiological action potential duration is restored, for example, during the first few weeks after cardioversion of persistent AF. This treatment concept that we call "targeted pharmacological reversal of electrical remodeling" would limit both cost and drug-induced side effects of antiarrhythmic drug therapy after cardioversion. The Flec-SL trial, ISECTN62728743, therefore tests the main hypothesis that targeted pharmacological reversal of electrical remodeling by short-term antiarrhythmic drug therapy for 4 weeks after cardioversion is not inferior to standard long-term antiarrhythmic drug therapy for the prevention of recurrent AF after cardioversion in a parallel group, randomized, multicenter, open, blinded end point analysis design. Based on its effectiveness and pharmacokinetic profile, flecainide is used to test the study hypothesis. The trial uses daily transtelephonic electrocardiographic monitoring for all patients and will be conducted within the German Atrial Fibrillation Competence NETwork (AFNET) to facilitate inclusion of patients from electrophysiologically oriented cardiology centers, ordinary hospitals, and office-based physicians.

The comparative effects of telmisartan and ramipril on P-wave dispersion in hypertensive patients: a randomized clinical study

BACKGROUND

Prolongation of P-wave times and increase of P-wave dispersion (PWD) were shown to be independent predictors of atrial fibrillation (AF). Angiotensin II receptor blockers (AARBs) and angiotensin-converting enzyme inhibitors (ACEIs) have beneficial effects on atrial conduction times. However, there are not enough data about the comparative effects of those drugs on PWD.

HYPOTHESIS

We aimed to compare the effects of telmisartan and ramipril on PWD after 6-month treatment in hypertensive patients.

METHODS

In all, 100 newly diagnosed hypertensive patients were enrolled in the study and were randomly assigned to two groups. Group 1 and Group 2 each consisted of 50 patients, taking daily doses of 80 mg telmisartan and 10 mg ramipril, respectively. Twelve-lead surface electrocardiograms (ECG) were recorded from all patients before and after 6-month drug therapy. The P-wave duration (Pdur) measurements were calculated from the 12-lead surface ECG.

RESULTS

When pretreatment PWD and Pmaximum values were compared with post-treatment values, a statistically significant decrease was found in both groups after 6 months (Group 1 and 2; p < 0.001 for PWD and Pmaximum). P-wave dispersion and Pmaximum values after treatment in Group 1 were statistically significantly lower than those in Group 2 after the 6-month treatment period (p = 0.01 for PWD; p = 0.008 for Pmaximum).

CONCLUSIONS

Telmisartan has a much greater lowering effect on PWD and Pmaximum values than ramipril. This finding may be important in the prevention of AF in hypertensive patients.

Targeting the renin-angiotensin-aldosterone-system in atrial fibrillation: a shift from electrical to structural therapy?

Despite its increasing incidence and prevalence, treatment options in atrial fibrillation (AF) are far from ideal and often limited. After decades of focus on the electrical aspects of AF with unsatisfactory results, recent research is focusing increasingly on the atrial structural remodelling that underlies the development of AF in different pathological conditions, such as hypertension, heart failure, diabetes mellitus and coronary artery disease. The aim of this review is to provide a comprehensive overview of the role of the renin-angiotensin-aldosterone-system in AF and to highlight the clinical evidence on renin-angiotensin-aldosterone-system blockade as a therapeutic option in AF.

Rate versus rhythm control in the management of patients with atrial fibrillation

The management of patients with atrial fibrillation involves three main areas: anticoagulation, rate control and rhythm control. Importantly, these are not mutually exclusive of each other. Anticoagulation is necessary for patients who are at a high risk of stroke; for example, those who are older than 75 years, or those who have hypertension, severe left ventricular dysfunction, previous cerebrovascular events, or diabetes. It is now clear that patients who are at a high risk of stroke require long-term anticoagulation with warfarin regardless of whether a rate-control or rhythm-control strategy is chosen. One possible exception might be patients who are apparently cured with catheter ablation. Several published trials comparing rate-control and rhythm-control strategies for the treatment of patients with atrial fibrillation have shown no difference in mortality between these approaches. The patients enrolled in these studies were typically over 65 years of age. Data comparing rate and rhythm strategies in patients who are younger than 60 years of age are limited. For more elderly patients, it seems reasonable to consider rate control as a primary treatment option and to reserve rhythm control for those who do not respond to rate control. For younger patients, we prefer to start with a rhythm-control approach and to reserve rate-control approaches for patients in whom antiarrhythmic drugs, ablation, or both, do not ameliorate the symptoms.

Losartan controlled blood pressure and reduced left ventricular hypertrophy but did not alter arrhythmias in hypertensive men with preserved systolic function

The effect of antihypertensive therapy on arrhythmias is controversial. An initial study in patients with chronic heart failure indicated that losartan, an angiotensin II receptor antagonist, may possess antiarrhythmic properties. However, the effect of AT1 receptor antagonists on arrhythmias of subjects with good systolic function has never been evaluated. Thirty-nine men with primary hypertension (18 without left ventricular hypertrophy [LVH], and 21 with LVH, aged 48.2 +/-8.6 and 50.5 +/-6.0 years, respectively), 15 healthy normotensive subjects (47.9 +/-8.5 years), and 14 highly trained athletes (34.1 +/-1.6 years) were studied. Transthoracic echocardiography and 24-hour Holter ambulatory monitoring were performed at baseline (without treatment). Hypertensive patients underwent the same examinations after 8 months of losartan administration. The prevalence and complexity of ventricular arrhythmias, and the frequency of supraventricular arrhythmias were increased in hypertensive patients with LVH compared to normotensive controls and athletes, at baseline. A similar significant reduction of blood pressure (BP) was noted in both groups of patients (p < 0.001). The LVH was reduced in hypertensives with LVH (the left ventricular mass index by 12%, the interventricular septum by 8.1%, the posterior wall by 7%, all p < 0.01). However, the arrhythmias did not change in either group of patients, even if all hypertensives were considered as 1 group. In conclusion, an 8-month course with losartan was effective in lowering BP and reducing LVH. However, the increased arrhythmias, which were registered in hypertensive patients with LVH at baseline, did not change.

Clinician underappreciation of interatrial block in a general hospital population

INTRODUCTION

Interatrial block (IAB; P wave > or =110 ms), a conduction delay between the right and left atria (LA), is highly prevalent and strongly associated with atrial tachyarrhythmias, LA electromechanical dysfunction as well as a risk of embolism. Nonetheless, clinicians' underappreciation of its existence and sequelae remains. We appraised this issue in a general hospital population.

METHODS

From the database of 730 12-lead electrocardiograms (ECGs) of patients aged 17-98 years (mean age 67.80 years; female patients 53.56%) in a tertiary care teaching general hospital, we recorded the computer-generated diagnostic readings of the ECGs and also the official cardiologist and hospitalist ECG interpretations and documentations. For increased sensitivity and specificity, and because the mode P wave duration in IAB is 120 ms, P waves > or =120 ms in any lead were used to diagnose IAB.

RESULTS

Six hundred and fifty-three ECGs (89.45%) showed sinus rhythm, and of those, IAB was documented on 309 ECGs (47.32%). LA enlargement was cited 29 times (3.97%), while possible LA enlargement and biatrial enlargement were cited 17 (2.32%) and 6 times (0.82%), respectively. One cardiologist's ECG interpretation documented IAB (0.32%), but none of the other medical staff diagnosed IAB or abnormal P wave duration.

CONCLUSION

This study demonstrates to extremes how IAB went undiagnosed in a general hospital population. Until more awareness of IAB is cultivated, such ignorance of the existence and sequelae of IAB could continue. Configuring ECG software to include P wave durations in computer-generated ECG readings could be useful in aiding diagnosis.

Latent Arterial Hypertension in Apparently Lone Atrial Fibrillation

INTRODUCTION

Longitudinal studies on lone AF are rare and the incidence of hypertension in this population unknown. This study aimed at investigating the incidence of arterial hypertension in patients with apparently lone atrial fibrillation (AF).

METHODS AND RESULTS

Out of 292 consecutive patients presented with permanent or paroxysmal AF, 32 patients were diagnosed as having lone AF according to strict criteria. Three patients were subjected to ablation of the ligament of Marshall, 14 patients to pulmonary vein isolation, and the remainder were treated with beta blockade. Patients were followed-up for a 1-3 year period. During follow-up, 14 patients were diagnosed as having arterial hypertension. Thirteen of them had recurrent AF despite ligament of Marshall ablation (1 patient), pulmonary vein isolation (4 patients) and beta blockade (8 patients). Cox regression analysis revealed that the only significant predictor of development of hypertension was complete or partial response to antiarrhythmic therapy (beta=3.82, S.E.=1.22, exp(b)=45.63, 95% C.I.=4.17-499.2, p=0.001), independent of age (beta=-0.01, p=0.74), sex (beta=-0.91, p=0.28), left ventricular ejection fraction (beta=0.06, p=0.52), left atrial size (beta=0.58, p=0.7) and kind of antiarrhythmic therapy (ablation or drug therapy) (beta=1.36, p=0.09). In patients with lone AF that did not respond at all to antiarrhythmic therapy, there was a 45.6 times higher risk of diagnosing hypertension during the next 3 years as compared to responders.

CONCLUSION

Approximately 44% of patients with an initial diagnosis of lone AF may represent occult cases of arterial hypertension. In these patients hypertension may affect AF recurrence and treatment outcomes, regardless of the mode of antiarrhythmic therapy used.

Antithrombotic Therapy for Stroke Prevention in Atrial Fibrillation

Atrial fibrillation (AF) is the most potent common risk factor for ischemic stroke. The number of Americans with nonvalvular AF is expected to increase markedly over the next several decades, making AF-related stroke an important public health concern. Given the individual and societal burden associated with AF-related stroke, efforts to identify and implement efficacious and acceptably safe therapeutic stroke prevention strategies are paramount. This article reviews the existing randomized trial evidence supporting the efficacy of oral vitamin K antagonists (ie, warfarin) or aspirin for preventing thromboembolism in AF, as well as completed and ongoing studies exploring novel antithrombotic agents including the oral direct thrombin inhibitor, ximelagatran, other antiplatelet agents (eg, clopidogrel), factor Xa inhibitors, and other pharmacological agents and additional therapeutic approaches such as mechanical devices and surgical procedures to obliterate the left atrial appendage.

Errors and pitfalls in the non-invasive management of atrial fibrillation

Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice while it has a significant impact on morbidity and mortality. The errors and pitfalls in the management of AF patients are not uncommon. These include errors in detection and management of the underlying conditions that promote and perpetuate the arrhythmia, in the selection and monitoring of antithrombotic treatment, in the selection of appropriate strategy for arrhythmia management (rate or rhythm control), in the cardioversion procedure, in the prevention of recurrence after cardioversion, in the acute or chronic control of heart rate, and in the monitoring of drug toxicities. The heterogeneity of the disease along with the diversity of current treatment options mainly account for these problems. Nevertheless, deep knowledge of the evidence-based therapeutic approaches, as well as the development of individualized therapeutic strategies, can substantially improve the effective management of such patients.

Rate Control vs Rhythm Control Strategies in Atrial Fibrillation

Rhythm management for atrial fibrillation is a subject of intense interest. In this review, the two main strategies for rhythm management in atrial fibrillation, the "heart rate control" strategy and the "heart rhythm control" strategy, are discussed under several headings. Some of the basic issues surrounding heart rate control and heart rhythm control and their study in clinical trials are reviewed. Seven published trials that deal with a comparison of these two strategies are reviewed in some detail. In summary, no distinct advantage of the rhythm control strategy has been identified so far. With respect to pharmacologic therapies and the type of patient studied in most of these trials, advantages seem to accrue to the rate control strategy. Those advantages include fewer adverse drug effects, fewer hospitalizations, and lower cost. Two trials studying quite different patients, and in one case quite different drug therapies, are currently in progress, and these two trials are also briefly reviewed. Current guidelines have not taken into account fully the findings of the studies described in this review, and comment is offered on the current guidelines. Finally, some of the possibilities for future research around this question are highlighted.

Treatment and prevention of atrial fibrillation with nonantiarrhythmic pharmacologic therapy

Atrial fibrillation is one of the most frequent heart rhythm disturbances found in clinical practice. Anticoagulation, rate control, cardioversion, and ablative procedures have been the mainstay of treatment. The frequent recurrence of atrial fibrillation and the side effects when antiarrhythmic drugs are used have led to dissatisfaction with available treatment of this arrhythmia. Pharmacologic therapy with angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, statins, and perhaps aldosterone and calcium channel blockers may have a role in the prevention of atrial fibrillation onset and recurrence. We summarize the possible biologic mechanisms and the clinical observations supporting the use of non-antiarrhythmic medications in the prevention of atrial fibrillation.

Possible pathophysiologic mechanisms supporting the superior stroke protection of angiotensin receptor blockers compared to angiotensin-converting enzyme inhibitors: clinical and experimental evidence

Stroke is a major cause of death and disability and its incidence increases linearly with age and the level of systolic and diastolic blood pressure. Stroke, besides being a cause of long-term disability for the affected person, also imposes a significant burden on society and healthcare costs. Although good blood pressure control is very critical for stroke prevention, angiotensin receptor blockers (ARBs) may be superior to angiotensin-converting enzyme inhibitors (ACEIs) for the same degree of blood pressure control. This hypothesis has clinical and experimental support. ARBs prevent stroke incidence by blocking the angiotensin II (AII), AT1 receptors preventing brain ischaemia and allowing AII to stimulate the unoccupied AT2 receptors, which improve brain ischaemia. ACEIs, by reducing AII generation, are less effective in preventing stroke. This hypothesis provides evidence that AII plays an important role in the prevention of stroke. Certain ARBs like losartan, and telmisartan, irbesartan and candesartan possess additional properties which may play a role in stroke prevention, which is independent of AII. These include antiplatelet aggregating, hypouricemic, antidiabetic and atrial antifibrillatory effects. However, the most critical factor in stroke prevention is good blood pressure control irrespective of drug used.

Interrelationships Between the Autonomic Nervous System and Atrial Fibrillation

Mechanisms responsible for atrial fibrillation are not completely understood but the autonomic nervous system is a potentially potent modulator of the initiation, maintenance, termination and ventricular rate determination of atrial fibrillation. Complex interactions exist between the parasympathetic and sympathetic nervous systems on the central, ganglionic, peripheral, tissue, cellular and subcellular levels that could be responsible for alterations in conduction and refractoriness properties of the heart as well as the presence and type of triggered activity, all of which could contribute to atrial fibrillation. These dynamic inter-relationships may also be altered dependent upon other neurohumoral modulators and cardiac mechanical effects from ventricular dysfunction and congestive heart failure. The clinical implications regarding the effects of the autonomic nervous system in atrial fibrillation are widespread. The effects of modulating ganglionic input into the atria may alter the presence or absence of atrial fibrillation as has been highlighted from ablation investigations. This article reviews what is known regarding the inter-relationships between the autonomic nervous system and atrial fibrillation and provides state of the art information at all levels of autonomic interactions.

Oral vitamin C administration reduces early recurrence rates after electrical cardioversion of persistent atrial fibrillation and attenuates associated inflammation

BACKGROUND

Inflammation and oxidative stress have been recently implicated in the pathophysiology of atrial fibrillation (AF). The aim of this study was to examine the potential benefit of vitamin C on the early recurrence rates and on inflammatory indices after successful cardioversion of persistent AF, as well as to investigate the time course of changes in these indices post-cardioversion.

METHODS

We prospectively studied 44 consecutive patients after successful electrical cardioversion of persistent AF. All patients received standard treatment and were randomised in one to one fashion to either oral vitamin C administration or no additional therapy. We followed-up the patients for 7 days performing successive measurements of white blood cell (WBC) count, C-reactive protein (CRP), fibrinogen, and ferritin levels.

RESULTS

One week after successful cardioversion, AF recurred in 4.5% of patients in the vitamin C group and in 36.3% of patients in the control group (p=0.024). Compared to baseline values, inflammatory indices decreased after cardioversion in patients receiving vitamin C but did not change significantly in the control group. A significant variance was found in the serial measurements of WBC counts (F=5.86, p=0.001) and of fibrinogen levels (F=4.10, p=0.0084) in the two groups. In the vitamin C group CRP levels were lower on the seventh day (p<0.05). CRP and fibrinogen levels were higher in patients who relapsed into AF compared to patients who maintained sinus rhythm (F=2.77, p=0.044 and F=3.51, p=0.017, respectively).

CONCLUSIONS

These findings suggest that vitamin C reduces the early recurrence rates after cardioversion of persistent AF and attenuates the associated low-level inflammation. These effects indicate that therapeutic approaches targeting at inflammation and oxidative stress may exert favourable effects on atrial electrical remodeling.

Recent hypertension trials: implications and controversies

The pharmacologic treatment of hypertension has been extensively studied by clinical trials. These studies have provided definitive evidence of a treatment benefit, and the weight and consistency of the clinical evidence has led to uniformity in many aspects of treatment recommendations worldwide. However, controversies remain-in particular, whether specific classes of drug therapy offer benefits for cardiovascular disease prevention beyond the expected benefits of blood pressure lowering per se. Updated large-scale epidemiologic studies and the meta-analysis of clinical trial data have better informed this debate and emphasized that the main driver of clinical benefit from blood pressure-lowering therapy is the magnitude of blood pressure reduction and perhaps the speed at which it is achieved. However, clinical trials are of short duration, and there are more marked drug-specific differences in intermediate cardiovascular structure, functional, and metabolic end points. The challenge is to interpret their significance with regard to longer term outcomes. Finally, although blood pressure lowering is undoubtedly beneficial, the concepts of single risk factor intervention and arbitrary blood pressure thresholds and treatment goals are being challenged by the recognition that the real target is cardiovascular disease risk. Undoubtedly, the most effective way to "go beyond blood pressure" is to add a statin.

Inhibition of angiotensin II signaling and recurrence of atrial fibrillation in AFFIRM

OBJECTIVES

We investigated whether inhibition of endogenous angiotensin II signaling reduces the recurrence rate of atrial fibrillation (AF) in patients enrolled in the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study.

BACKGROUND

Structural and electrical remodeling contribute to AF. Previous experimental studies have implicated the angiotensin II signaling pathway in this process, and recent clinical evidence supports a beneficial effect of inhibiting angiotensin II activity.

METHODS

Using the AFFIRM database, we retrospectively identified a cohort of patients randomized to the rhythm-control arm who were in sinus rhythm. Exposure to angiotensin II receptor blockers or angiotensin-converting enzyme inhibitors (ANGI) was determined, and the time to first recurrence of AF was compared between ANGI users and nonusers.

RESULTS

The study cohort included 732 patients not taking ANGI through the initial 2-month follow-up and 421 patients taking ANGI during this time. Patients in the ANGI group more likely had hypertension, diabetes, coronary artery disease, and congestive heart failure compared to patients not taking ANGI. Risk of AF recurrence in the ANGI treatment group did not differ from the risk observed in patients not taking the drugs (hazard ratio [HR] = 0.91, 95% confidence interval [CI] = 0.77-1.09). However, in patients with congestive heart failure or impaired left ventricular function, ANGI use was associated with a lower risk of AF recurrence.

CONCLUSIONS

This analysis provides evidence that ANGI use may be beneficial in some patient subgroups with AF and underscores the need for randomized clinical trials defining more fully the role of angiotensin II inhibition in treating AF.

Inflammation in the genesis and perpetuation of atrial fibrillation

The prevalence and persistence of atrial fibrillation (AF) and the relative inefficacy of the currently available pharmacotherapy requires development of new treatment strategies. Recent findings have suggested a mechanistic link between inflammatory processes and the development of AF. Epidemiological studies have shown an association between C-reactive protein and both the presence of AF and the risk of developing future AF. In case-control studies, C-reactive protein is significantly elevated in AF patients and is associated with successful cardioversion. Moreover, C-reactive protein elevation is more pronounced in patients with persistent AF than in those with paroxysmal AF. Furthermore, treatment with glucocorticoids, statins, angiotensin converting enzyme inhibitors, and angiotensin II receptor blockers seems to reduce recurrence of AF. Part of this anti-arrhythmic effect may be through anti-inflammatory activity. This article reviews what is known about inflammation in genesis and perpetuation of AF, the putative underlying mechanisms, and possible therapeutic implications for the inhibition of inflammation as an evolving treatment modality for AF.

Symptomatic burden as an endpoint to evaluate interventions in patients with atrial fibrillation

Management of patients with atrial fibrillation (AF) is clinically challenging and has led to the development of new pharmacologic and nonpharmacologic therapies. However, no clear consensus on optimal endpoints for defining responses to therapy exists. This paradox arises largely because symptoms, often used to gauge efficacy of interventions, have not been well correlated with long-term "hard" endpoints such as stroke and death. One widely used symptom-based metric is "time to first symptomatic AF episode," but this correlates poorly with frequency of symptomatic episodes. Similarly, although quality-of-life (QOL) measures have been used, the precise and unbiased assessment of QOL is difficult to define and measure. The availability of implantable devices capable of monitoring and recording all AF episodes has made the accurate determination of total time in AF ("burden") possible. However, QOL tools and formal measures of AF burden do not correlate well, suggesting that measures of subjective well-being are important adjunct measures to conventional measures of disease severity when evaluating the therapeutic efficacy of treatments for AF. Although measurement of total AF burden requires invasive monitoring, symptomatic AF burden (defined by frequency, duration and severity of symptoms) can be determined in all patients with symptomatic AF and may serve as a valid endpoint, as elimination of symptoms is a common and realistic therapeutic goal. Therefore, we propose an algorithm to quantify symptomatic AF burden as an endpoint in clinical trials.