Heart failure, diastolic dysfunction and atrial fibrillation; mechanistic insight of a complex inter-relationship

Atrial fibrillation (AF) and heart failure (HF) commonly coexist, and their co-presence is associated with adverse outcomes relating to thromboembolic events, HF progression, hospitalisation and death. Diastolic dysfunction (DD) is also frequently present in patients with HF and is an independent predictor of hospitalisation and mortality. The presence of DD is a strong predictor of incident AF in patients with HF. In this review, we provide mechanistic insight into pathophysiological processes that frequently promote the occurrence of AF, HF and DD and outline the yin-yang relationship between AF, DD and HF. More recently, invasive studies have also shown that asymptomatic paroxysmal atrial fibrillation (PAF) is a common phenomenon in HF patients. We examine complex inter-relationships between PAF, HF and DD and speculate upon the possible clinical influence of undiagnosed PAF in HF patients.

Catheter ablation for paroxysmal and persistent atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most common cardiac arrhythmia seen in cardiovascular departments. Treatments include medical interventions and catheter ablation. Due to uncertainties in medical therapies for AF, and the need to continue sinus rhythm, ablation has been recently considered as a viable alternative. Many new ablation methods based on pulmonary vein isolation (PVI) have been developed.

OBJECTIVES

The primary objective of this review was to assess the beneficial and harmful effects of catheter ablation (CA) in comparison with medical treatment in patients with paroxysmal and persistent AF. The secondary objective was to determine the best regimen of CA.

SEARCH METHODS

Searches were run on The Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library Issue 3 2009, MEDLINE (1950 to August 2009), EMBASE (1980 to August 2009), the Chinese Biomedical Literature Database (1978 to August 2009) and the CKNI Chinese Paper Database (1994 to 2009) . Several journals published in Chinese were also handsearched.

SELECTION CRITERIA

Randomised controlled trials (RCTs) in people with paroxysmal and persistent AF treated by any type of CA method. Two reviewers independently selected the trials for inclusion.

DATA COLLECTION AND ANALYSIS

Assessments of risk of bias were performed by two reviewers, and relative risk (RR) and 95% confidence intervals (CI) were used for dichotomous variables. Meta-analysis were performed where appropriate.

MAIN RESULTS

A total of 32 RCTs (3,560 patients) were included. RCTs were small in size and of poor quality.CA compared with medical therapies: seven RCTs indicated that CA had a better effect in inhibiting recurrence of AF [RR 0.27; 95% CI 0.18, 0.41)] but there was significant heterogeneity. There was limited evidence to suggest that sinus rhythm was restored during CA (one small trial: RR 0.28, 95% CI 0.20-0.40), and at the end of follow-up (RR 1.87, 95% CI 1.31-2.67; I(2)=83%). There were no differences in mortality (RR, 0.50, 95% CI 0.04 to 5.65), fatal and non-fatal embolic complication (RR 1.01, 95% CI 0.18 to 5.68) or death from thrombo-embolic events (RR 3.04, 95% CI 0.13 to 73.43).Comparisons of different CAs; 25 RCTs compared CA of various kinds. Circumferential pulmonary vein ablation was better than segmental pulmonary vein ablation in improving symptoms of AF (p<=0.01) and in reducing the recurrence of AF (p<0.01). There is limited evidence to suggest which ablation method was the best.

AUTHORS' CONCLUSIONS

There is limited evidence to suggest that CA may be a better treatment option compared to medical therapies in the management of persistent AF. This review was also unable to recommend the best CA method.

Catheter ablation for atrial fibrillation in patients with left ventricular systolic dysfunction. A systematic review and meta-analysis

BACKGROUND

Atrial fibrillation (AF) and heart failure are often coexisting major public health burdens. Although several studies have reported partial restoration of systolic left ventricular (LV) function after catheter ablation for AF, the method is not widely applied in patients with LV dysfunction. We reviewed the results of AF ablation in patients with systolic LV dysfunction.

METHODS AND RESULTS

PubMed was searched for studies published after 2000 reporting original data on AF catheter ablation in adult patients with systolic LV dysfunction. Primary end point was the change of LV ejection fraction (LVEF) after catheter ablation; secondary endpoints were the changes of exercise capacity and quality of life after the procedure. We calculated mean difference (MD) of LVEF and 95% confidence interval (95% CI) using random-effects models. Heterogeneity was investigated by I(2) statistic, publication bias with Egger's test. The impact of covariates on LVEF improvement was evaluated with meta-regression analyses. Nine studies with a total of 354 patients with systolic LV dysfunction were analyzed. Study patients were mainly male with mean age 49 to 62 years, LVEF was moderately impaired and ranged in all but 1 study from 35% to 43%. LVEF improved after ablation with a MD of 11.1% (95% CI: 7.1-15.2, P < .001). Heterogeneity among analyzed studies was significant (I(2) = 92.9, P < .001). No potential publication bias was found. In meta-regression analyses, the proportion of patients with coronary artery disease was inversely related with LVEF improvement (P < .0001) whereas there was no association between the LVEF change and the proportion of patients with nonparoxysmal AF or the proportion of patients without AF recurrences during follow-up.

CONCLUSIONS

AF ablation in patients with systolic LV dysfunction results in significant improvement of LV function, but the extent of this improvement is heterogeneous. Patients with coronary artery disease seem to benefit less than patients with other underlying diseases. These results may be explained by patient selection.

Cardiac function in relation to rhythm outcome after intraoperative epicardial left atrial cryoablation

Objectives

To assess the effects of intraoperative left atrial epicardial cryoablation on rhythm and atrial and ventricular function.

Design

Thirty five patients with coronary artery disease and documented atrial fibrillation underwent coronary artery bypass surgery and concomitant cryoablation. An age and gender matched control group of 35 patients with atrial fibrillation underwent bypass surgery alone. Echocardiography was performed 9 ± 32 days before and 22 ± 6 months after surgery.

Results

The proportion of patients in sinus rhythm at follow-up was 63% and 34% (p = 0.04) in the cryoablation and control groups, respectively. In patients with sinus rhythm both before surgery and at follow-up, the left atrial area increased (p = 0.002) and the mitral annular excursion during atrial contraction decreased (p = 0.01) after cryoablation. The mitral flow velocity during atrial systole decreased after cryoablation (p = 0.002). The LV diameter increased (p = 0.03) and the left ventricular ejection fraction (LVEF) decreased (p = 0.03) in cryoablated but not in control patients. Continued deterioration was seen in patients with atrial fibrillation both pre- and postoperatively.

Conclusions

At long-term follow-up, a significantly higher proportion of patients was in sinus rhythm in the cryoablation than in the control group. The atrial and ventricular function had decreased at follow-up two years after surgery. This decrease was small and occurred within or close to the reference values in patients with sinus rhythm at follow-up, while patients remaining in atrial fibrillation showed a significant continued deterioration. Some subgroups were small, and the findings, although statistically significant, should be interpreted with caution.

Meta-analysis of the effectiveness and safety of catheter ablation of atrial fibrillation in patients with versus without left ventricular systolic dysfunction

Catheter ablation is a promising therapy for atrial fibrillation (AF), but its utility in patients with left ventricular systolic dysfunction (LVSD) is uncertain. The objectives of this study were to perform a systematic review and meta-analysis of randomized and observational studies comparing the rates of recurrent AF, atrial tachycardia (AT), and complications after AF catheter ablation in those with versus without LVSD and to summarize the impact of catheter ablation on the left ventricular ejection fraction. Seven observational studies and 1 randomized trial were included (total n = 1,851). Follow-up ranged from 6 to 27 months. In those with LVSD, 28% to 55% were free of AF or AT on follow-up after 1 AF catheter ablation, increasing to 64% to 96% after a mean of 1.4 procedures. The relative risk for recurrent AF or AT in those with versus without LVSD was 1.5 (95% confidence interval 1.2 to 1.8, p <0.001) after 1 procedure and 1.2 (95% confidence interval 0.9 to 1.5, p = 0.2) after multiple procedures. No difference in complications was observed in patients with (3.5%) versus without (2.5%) heart failure (p = 0.55). After catheter ablation, those with LVSD experienced a pooled absolute improvement in the left ventricular ejection fraction of 0.11 (95% confidence interval 0.07 to 0.14, p <0.001). In conclusion, patients with and without LVSD had similar risk for recurrent AF or AT after catheter ablation, but repeat procedures were required more often in those with LVSD. Significant improvements in left ventricular ejection fractions after ablation were observed in those with LVSD. Randomized trials are needed given the limitations of present data.

Early and late cardiac ventricular reverse remodeling after catheter ablation for lone paroxysmal atrial fibrillation

AIM

We sought to explore ventricular function in patients with lone paroxysmal atrial fibrillation (AF) and determine the mid- and long-term impact of pulmonary vein isolation on cardiac remodeling.

BACKGROUND

The relationship between tachyarrhythmia and ventricular dysfunction is still a matter of debate. Tachycardia-induced cardiomyopathy is defined as reversible myocardial dysfunction following treatment for tachyarrhythmia.

METHOD

We prospectively studied 31 patients (56.4 ± 10 years) presenting with paroxysmal-AF who were treated successfully by catheter ablation and 15 age-matched controls. Left and right ventricular functions were assessed by echocardiography at baseline and at 3-month and 1-year follow-up.

RESULTS

In AF-patients, LV-function was slightly lower at baseline than controls (LV-ejection fraction was 60% versus 64%; P = 0.06). More impressive, systolic peak velocity on Doppler tissue imaging was 9 cm/s in AF patients (versus 12 cm/s; P = 0.0004). LV global longitudinal strain was also significantly different between the two groups (patients: -16% versus controls: -19%; P = 0.005). At 1-year follow-up, most functional parameters significantly improved in the AF-patients and no longer differed from the controls. Right ventricular (RV) function was also depressed in AF patients at baseline. At 1-year follow-up, tissue Doppler showed improvement in RV-S' (+27%, P = 0.007) and RV peak systolic strain (+36%, P<0.0001) and became comparable to controls.

CONCLUSION

We demonstrate that some degree of arrhythmic cardiomyopathy exists in patients presenting with lone paroxysmal-AF. Catheter ablation improved RV and LV functions. Longitudinal function is the most sensitive component of ventricular systole to monitor when looking for this cardiac reverse remodeling.

Left ventricular systolic dysfunction by itself does not influence outcome of atrial fibrillation ablation

AIMS

The objective of the study was to analyse the influence of left ventricular (LV) ejection fraction (EF) on the outcomes of atrial fibrillation (AF) ablation after a first procedure. Pre-procedural predictors of recurrences after AF ablation can be useful for patient information and selection of candidates. The independent influence of LV systolic dysfunction on recurrence rate has not been studied.

METHODS AND RESULTS

A case-control study (1:1) was conducted with a total of 72 patients: 36 cases (depressed LVEF) and 36 controls (normal LVEF). Patients were matched by left atrial diameter (LAD), the presence of arterial hypertension, and other variables that might influence the results (age, gender and paroxysmal vs. persistent AF). There were no statistical differences in the variables used to perform the matching. Patients with depressed LVEF had higher LV end diastolic diameter (55.6 +/- 6.2 vs. 52.4 +/- 5.5, P = 0.03), higher LV end systolic diameter (40.3 +/- 6.9 vs. 32.6 +/- 4.3, P < 0.001), lower LVEF (41.4 +/- 8.0 vs. 63.1 +/- 5.5, P < 0.001) and were more likely to have structural heart disease. After a mean follow-up of 16 +/- 13 months, survival analysis for AF recurrences showed no differences between patients with depressed vs. normal LVEF (50.0 vs. 55.6%, log rank = 0.82). Cox regression analysis revealed LAD to be the only variable correlated to recurrence [OR 1.11 (1.01-1.22), P = 0.03]. Analysis at 6 months showed a significant increase in LVEF (43.23 +/- 7.61 to 51.12 +/- 13.53%, P = 0.01) for the case group.

CONCLUSION

LV systolic dysfunction by itself is not a predictor of outcome after AF ablation. LAD independently correlates with outcome in patients with low or normal LVEF.

Imaging and atrial fibrillation: the role of multimodality imaging in patient evaluation and management of atrial fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia, and is associated with an increased risk of cardiac morbidity and mortality. In this review, the role of multimodality imaging in the evaluation and treatment of AF is discussed in two main parts. First, an overview of the initial assessment of an AF patient is provided, including the role of different imaging techniques. Conditions that are associated with AF (coronary artery disease, heart failure, valvular heart disease, and left ventricular hypertrophy), and the assessment with various imaging modalities, will be reviewed. Furthermore, left atrial size assessment and the screening for thrombus formation are addressed. Secondly, the role of imaging in the invasive treatment of AF with catheter ablation is reviewed. Issues that should be considered before the procedure including contra-indications and pulmonary vein and left atrial anatomy will be discussed. Furthermore, the integration of different imaging modalities during catheter ablation is explored. Finally, an overview of the role of imaging in the follow-up of patients treated with catheter ablation will be provided.

The role of pulmonary veins in atrial fibrillation: a complex yet simple story

Atrial fibrillation (AF) is the most common cardiac arrhythmia, with increased incidence among the elderly population. The concept that ectopic activity in pulmonary veins (PVs) could be responsible for triggering AF has been put forward, and the inter-relationship between PVs and left atrium has been the subject of many anatomical and physiological investigations. Variable configuration of action potentials among various PV cardiomyocytes has been reported. PV myocytes were shown to have a higher resting membrane potential and a lower action potential amplitude and duration than the left atrium. Much evidence has accumulated to indicate that spontaneous depolarization and/or re-entry from PVs could be the mode by which AF is initiated and/or sustained. Attempts have been made to link AF in certain pathophysiological states, notably, congestive heart failure, valvular disease and hyperthyroidism to PVs. There has been evidence to suggest that an increase in PV diameter may be the trigger for initiating AF. However, there is limited clinical knowledge available on the nature of the antiarrhythmic drugs that act upon PVs to alleviate AF. Most drugs currently employed are the standard agents generally utilized for the treatment of AF. Radiofrequency ablation (RFA) of the PVs and its isolation from the left atrium has become a major curative measure of AF. It is also possible that pharmacotherapy may be more effective or provide extra benefit to patients after a RFA procedure. The trend of the clinical evidence seems to suggest that a hybrid treatment may be beneficial in some population of patients.

Long-term improvement in left ventricular strain after successful catheter ablation for atrial fibrillation in patients with preserved left ventricular systolic function

BACKGROUND

The effect of successful catheter ablation on left ventricular (LV) strain in patients with preserved LV systolic function is unknown. The aim of the present study was to assess the long-term effects of catheter ablation for atrial fibrillation (AF) on LV strain and strain rate in patients with preserved LV ejection fraction.

METHODS AND RESULTS

In 78 patients undergoing catheter ablation for AF, speckle tracking strain imaging was performed to assess LV strain in 3 directions (radial, circumferential, and longitudinal) at baseline and after 12-month follow-up. The study population was divided into 2 groups, according to the maintenance of sinus rhythm (SR) during follow-up. After 13.8+/-4.7 months of follow-up, 54 patients (69%) were in SR (SR group), whereas 24 patients (31%) had recurrence of AF (AF group). No significant changes in LV ejection fraction from baseline to follow-up were noted (60+/-7% versus 59+/-7%, P=NS). Circumferential strain improved significantly in the SR group (-18.3+/-3.2% versus -20.4+/-3.8%, P<0.001), whereas it remained unchanged in the AF group (-18.9+/-3.5% versus -17.9+/-3.1%, P=NS). In the SR group, significant improvements in LV longitudinal strain and strain rate were noted, whereas in the AF group, LV longitudinal strain and strain rate deteriorated significantly at long-term follow-up.

CONCLUSIONS

After successful catheter ablation, LV circumferential and longitudinal strain and strain rate improve significantly in patients who maintain SR. In contrast, a decrease in LV longitudinal strain and strain rate is observed in patients with recurrence of AF.

Atrial fibrillation in heart failure: current treatment of patients with remodeled atria

Atrial fibrillation (AF) and chronic heart failure (CHF) can be caused by each other, and therefore constitute a vicious circle. The prevalence of both conditions is about 1% in industrialized countries and increases with age. Although mortality is increased in heart failure, the additional prognostic relevance of AF in these patients is less clear. AF in patients with CHF can worsen heart failure symptoms, cause complications (eg, stroke), and is difficult to treat. Thus, prevention of AF entirely is an important goal. This review summarizes recent data concerning prognostic relevance, treatment, and means of primary and secondary prevention of AF in patients with CHF.

Atrial fibrillation in congestive heart failure: current management

Atrial fibrillation (AF) and congestive heart failure are common conditions and each predisposes to the development of the other. Basic research using animal models of the two conditions continues to yield insights that may improve therapies. The role of medical therapies aimed at the underlying structural changes in AF continues to be a subject of ongoing studies. Cardiac resynchronization therapy is effective in appropriately selected patients with both sinus rhythm and AF. Catheter ablation is emerging as a potential alternative to antiarrhythmic drug therapy, but large randomized trials will be needed to assess its role.