Improvement of Maximal Exercise Performance After Catheter-Ablation of Atrial Fibrillation and Its Prognostic Significance for Long-Term Rhythm Outcome

2024 HRS expert consensus statement on arrhythmias in the athlete: Evaluation, treatment, and return to play

Youth and adult participation in sports continues to increase, and athletes may be diagnosed with potentially arrhythmogenic cardiac conditions. This international multidisciplinary document is intended to guide electrophysiologists, sports cardiologists, and associated health care team members in the diagnosis, treatment, and management of arrhythmic conditions in the athlete with the goal of facilitating return to sport and avoiding the harm caused by restriction. Expert, disease-specific risk assessment in the context of athlete symptoms and diagnoses is emphasized throughout the document. After appropriate risk assessment, management of arrhythmias geared toward return to play when possible is addressed. Other topics include shared decision-making and emergency action planning. The goal of this document is to provide evidence-based recommendations impacting all areas in the care of athletes with arrhythmic conditions. Areas in need of further study are also discussed.

Exercise echocardiography to assess left atrial function in patients with symptomatic AF

Background

Left atrial (LA) function contributes to the augmentation of cardiac output during exercise. However, LA response to exercise in patients with atrial fibrillation (AF) is unknown. We explored the LA mechanical response to exercise and the association between LA dysfunction and exercise intolerance.

Methods

We recruited consecutive patients with symptomatic AF and preserved left ventricular ejection fraction (LVEF). Participants underwent exercise echocardiography and cardiopulmonary exercise testing (CPET). Two-dimensional and speckle-tracking echocardiography were performed to assess LA function at rest and during exercise. Participants were grouped according to presenting rhythm (AF vs sinus rhythm). The relationship between LA function and cardiorespiratory fitness in patients maintaining SR was assessed using linear regression.

Results

Of 177 consecutive symptomatic AF patients awaiting AF ablation, 105 met inclusion criteria; 31 (29.5 %) presented in AF whilst 74 (70.5 %) presented in SR. Patients in SR augmented LA function from rest to exercise, increasing LA emptying fraction (LAEF) and LA reservoir strain. In contrast, patients in AF demonstrated reduced LAEF and reservoir strain at rest, with failure to augment either parameter during exercise. This was associated with reduced VO2Peak compared to those in SR (18.4 ± 5.6 vs 22.5 ± 7.7 ml/kg/min, p = 0.003). In patients maintaining SR, LAEF and reservoir strain at rest and during exercise were associated with VO2Peak, independent of LV function.

Conclusion

The maintenance of SR in patients with AF is associated with greater LA reservoir function at rest and greater augmentation with exercise compared to patients in AF. In patients in SR, reduced LA function is associated with reduced exercise tolerance, independent of LV function.

Discovery of TBX20 as a Novel Gene Underlying Atrial Fibrillation

Atrial fibrillation (AF), the most prevalent type of sustained cardiac dysrhythmia globally, confers strikingly enhanced risks for cognitive dysfunction, stroke, chronic cardiac failure, and sudden cardiovascular demise. Aggregating studies underscore the crucial roles of inherited determinants in the occurrence and perpetuation of AF. However, due to conspicuous genetic heterogeneity, the inherited defects accounting for AF remain largely indefinite. Here, via whole-genome genotyping with genetic markers and a linkage assay in a family suffering from AF, a new AF-causative locus was located at human chromosome 7p14.2-p14.3, a ~4.89 cM (~4.43-Mb) interval between the markers D7S526 and D7S2250. An exome-wide sequencing assay unveiled that, at the defined locus, the mutation in the TBX20 gene, NM_001077653.2: c.695A>G; p.(His232Arg), was solely co-segregated with AF in the family. Additionally, a Sanger sequencing assay of TBX20 in another family suffering from AF uncovered a novel mutation, NM_001077653.2: c.862G>C; p.(Asp288His). Neither of the two mutations were observed in 600 unrelated control individuals. Functional investigations demonstrated that the two mutations both significantly reduced the transactivation of the target gene KCNH2 (a well-established AF-causing gene) and the ability to bind the promoter of KCNH2, while they had no effect on the nuclear distribution of TBX20. Conclusively, these findings reveal a new AF-causative locus at human chromosome 7p14.2-p14.3 and strongly indicate TBX20 as a novel AF-predisposing gene, shedding light on the mechanism underlying AF and suggesting clinical significance for the allele-specific treatment of AF patients.

The role of cardiopulmonary exercise testing in risk stratification and prognosis of atrial fibrillation: a scoping review of the literature

BACKGROUND

Cardiopulmonary exercise testing (CPET) is a significant tool for evaluating exercise capacity in healthy individuals and in various pulmonary and cardiovascular conditions, quantifying symptoms and predicting outcomes. Atrial fibrillation (AF) poses a significant burden on patients and health systems; a research marathon is ongoing for discovering the pathophysiologic substrate, natural history, prognostic tools and optimal treatment strategies for AF. Among the plethora of variables measured during CPET, there is a series of parameters of interest concerning AF.

METHODS

We conducted a scoping review aiming to identify significant CPET-related parameters linked to AF, as well as indicate the impact of other cardiac disease-related variables. We searched PubMed from its inception to 12 January 2022 for reports underlining the contribution of CPET in the assessment of patients with AF. Only clinical trials, observational studies and systematic reviews were included, while narrative reviews, expert opinions and other forms of manuscripts were excluded.

RESULTS

In our scoping review, we report a group of heterogeneous, thus noteworthy parameters relevant to the potential contribution of CPET in AF. CPET helps phenotype AF populations, evaluates exercise capacity after cardioversion or catheter ablation, and assesses heart rate response to exercise; peak VO₂ and VE/VCO₂, commonly measured indices during CPET, also serve as prognostic tools in patients with AF and heart failure.

CONCLUSIONS

CPET seems to hold a clinically important predictive value for future cardiovascular events both in patients with pre-existing cardiac conditions and in healthy individuals. CPET variables may play a fundamental role in the prediction of future AF-related events.

Improvement of Maximal Exercise Performance After Catheter-Ablation of Atrial Fibrillation and Its Prognostic Significance for Long-Term Rhythm Outcome

Background

Rhythm control may improve functional capacity in patients with atrial fibrillation (AF). Long‐term exercise tolerance improvement and its prognostic implications following catheter‐ablation (CA) of paroxysmal and nonparoxysmal AF are underreported.

Methods and Results

Consecutive patients underwent cardiopulmonary exercise testing just before and 12 months after their index CA of AF. Follow‐up 24‐hour Holter recordings were obtained at 6‐month intervals post‐CA, and any atrial arrhythmia >30 seconds detected after 3 months postprocedure was considered AF recurrence. Of 110 patients (mean age 57.5±10.6 years, 77.2% males) with paroxysmal AF (n=66) or nonparoxysmal AF (n=44), the 12‐month exercise tolerance improved significantly in those who maintained sinus rhythm during the first 12 months post‐CA (n=96), but not in patients with AF recurrence (n=14). After CA, the 12‐month respiratory exchange ratio at maximal workload significantly increased in patients with paroxysmal AF, whereas those with nonparoxysmal AF significantly reduced their heart rate during the 12‐month cardiopulmonary exercise testing (all P≤0.001). During the follow‐up of 42.8±7.8 months, a total of 29 patients (26.3%) experienced recurrent AF. On multivariate analysis including patients without recurrent AF at 12 months after CA, the extent of work time improvement at follow‐up cardiopulmonary exercise testing was independently associated with the rhythm outcome beyond 12 months postprocedure (hazard ratio of 0.936 [95% CI, 0.894–0.979] for each 10 seconds increase in the work time following ablation, P=0.004).

Conclusions

CA of AF was associated with recovery of exercise intolerance in patients with paroxysmal AF or nonparoxysmal AF. Inability to improve exercise capacity at 12 months post‐CA was an independent risk factor for later AF recurrence.