Exploring the Uncertainty　― Is Left Atrial Reservoir Strain the Missing Piece? ―

Catheter ablation (CA) is now an established treatment for atrial fibrillation (AF) and has emerged as the first-line therapy for some selected patients.¹ However, recurrence after CA remains an unsolved issue. Historically, AF recurrence was mainly due to reconnection of the pulmonary veins after pulmonary vein isolation (PVI), but the durability of PVI has improved with advances in technology,^2–6 and the focus has shifted to the substrate of non-PV foci created by atrial structural and/or electrical remodeling as the cause of AF recurrence.

Article p 153

Several preprocedural examinations, such as electrocardiography,^7,8 echocardiography,⁹ and biomarkers,^10,11 have been evaluated for their efficacy in predicting the recurrence of AF after CA (Figure). Regarding echocardiography, the left atrial dimension (LAD) and left atrial volume index (LAVI) are reported as simple but strong predictors for both the incidence and AF recurrence after PVI. When the AF duration (AF burden) is longer, the left atrium (LA) becomes larger, known as structural remodeling. Therefore, it is easy to assume that the recurrence rate of AF in patients with a remodeled larger LA would be high. On the other hand, evaluating the early phase of structural remodeling or other electrical remodeling in patients without a large LA has been challenging. Electrophysiologists use high-resolution mapping systems to confirm LA structural and electrical remodeling during CA. If the preprocedural evaluation is insufficient, we can sometimes experience a devastating “nightmare” during the procedure.

Figure.

Predicting AF recurrence after PVI by comprehensive evaluation. AF, atrial fibrillation; BNP, B-type natriuretic peptide; HANP, human atrial natriuretic peptide; LAD, left atrial dimension; LAS_R, left atrial reservoir strain; LAVI, left atrial volume index; LV-GLS, left ventricular global longitudinal strain; PVI, pulmonary vein isolation.

LA strain analysis has recently been highlighted as a prognostic marker in several cardiovascular diseases.¹² Regarding AF, reports have suggested that LA strain is a useful non-invasive modality to predict new-onset or newly diagnosed AF in patients with heart failure or cryptogenic stroke.^13,14

In this issue of the Journal, Knappe et al.¹⁵ evaluate the association between pre-evaluated left atrial reservoir strain (LAS_R) and AF recurrence after PVI in a total of 132 patients who underwent de novo PVI between December 2017 and January 2019. In a multivariable Cox regression analysis, they found that decreasing LAS_R was associated with the recurrence of AF with a hazard ratio of 0.83, 95% confidence interval 0.73–0.93; P=0.001. After including other clinical variables with age, sex, and type of AF, LAS_R remained a significant factor for predicting the recurrence of AF after PVI. Moreover, the authors compared the LAS_R to the LA dimension, left ventricular global longitudinal strain (LV-GLS), and left ventricular ejection fraction (LVEF) as predictive factors for AF recurrence, and found that LAS_R was the most predictive for AF recurrence. They concluded that LAS_R could be helpful in risk stratification regarding AF recurrence after PVI.

Because significant evidence of AF ablation as the rhythm control therapy has been reported, the case numbers undergoing catheter ablation have increased worldwide. However, there is still recurrence to some extent after PVI; therefore, risk stratification for recurrence after CA is essential in this field. This study is clinically meaningful for classifying patients with a high risk of AF recurrence after PVI. If patients are classified into a high-risk category by the preprocedural evaluation, additional ablation procedures beyond PVI would be considered, or a choice of medical therapy other than CA would be alternatively selected through decision-making among patients and doctors.

However, several limitations still exist in this study. Because evaluating LAS_R is not yet a generalized technique, it cannot be routinely evaluated in daily practice. Additionally, all patients in the study underwent echocardiography under sinus rhythm, and it would be challenging to evaluate the data under AF rhythm. Therefore, applying these results to all AF patients may not be possible. Thus the present report is a pilot study for predicting AF recurrence after PVI utilizing LAS_R, and the authors have already planned a multicenter study with more cases. More robust evidence with these parameters for exploring high-risk patients of AF recurrence after PVI is anticipated.

Another issue always exists after AF ablation; that is, detection of AF recurrence, especially in asymptomatic events. It could always be argued how to detect AF recurrence. In this study, only 24-hour Holter ECG at 12 months was performed for patients without symptoms; therefore, the recurrence rate could be underestimated. Detecting asymptomatic paroxysmal AF recurrence is still a challenge, even today. Those 2 uncertainties, the prediction and detection of AF recurrence after CA, are not entirely solved clinical questions; comprehensive evaluation using multimodalities and detailed follow-up with advanced technology will be germane to this challenging issue.

Conflict of Interest

The authors declare no conflict of interest related to this work.

References

• 1.   Joglar JA, Chung MK, Armbruster AL, Benjamin EJ, Chyou JY, Cronin EM, et al. 2023 ACC/AHA/ACCP/HRS Guideline for the diagnosis and management of atrial fibrillation: A report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation 2024; 149: e1–e156.
• 2.   Das M, Loveday JJ, Wynn GJ, Gomes S, Saeed Y, Bonnett LJ, et al. Ablation index, a novel marker of ablation lesion quality: Prediction of pulmonary vein reconnection at repeat electrophysiology study and regional differences in target values. Europace 2017; 19: 775–783.
• 3.   Whitaker J, Fish J, Harrison J, Chubb H, Williams SE, Fastl T, et al. Lesion index-guided ablation facilitates continuous, transmural, and durable lesions in a porcine recovery model. Circ Arrhythm Electrophysiol 2018; 11: e005892.
• 4.   Martin CA, Martin R, Gajendragadkar PR, Maury P, Takigawa M, Cheniti G, et al. First clinical use of novel ablation catheter incorporating local impedance data. J Cardiovasc Electrophysiol 2018; 29: 1197–1206.
• 5.   Phlips T, Taghji P, El Haddad M, Wolf M, Knecht S, Vandekerckhove Y, et al. Improving procedural and one-year outcome after contact force-guided pulmonary vein isolation: The role of interlesion distance, ablation index, and contact force variability in the ‘CLOSE’-protocol. Europace 2018; 20: f419–f427.
• 6.   Andrade JG, Wazni OM, Kuniss M, Hawkins NM, Deyell MW, Chierchia GB, et al. Cryoballoon ablation as initial treatment for atrial fibrillation: JACC State-of-the-Art Review. J Am Coll Cardiol 2021; 78: 914–930.
• 7.   Saito D, Fukaya H, Oikawa J, Sato T, Matsuura G, Arakawa Y, et al. Atrial late potentials are associated with atrial fibrillation recurrence after catheter ablation. J Arrhythm 2022; 38: 991–996.
• 8.   Zhang ZR, Ragot D, Massin SZ, Suszko A, Ha ACT, Singh SM, et al. P-wave duration/amplitude ratio quantifies atrial low-voltage area and predicts atrial arrhythmia recurrence after pulmonary vein isolation. Can J Cardiol 2023; 39: 1421–1431.
• 9.   Bras PG, Cunha PS, Timoteo AT, Portugal G, Galrinho A, Laranjo S, et al. Evaluation of left atrial strain imaging and integrated backscatter as predictors of recurrence in patients with paroxysmal, persistent, and long-standing persistent atrial fibrillation undergoing catheter ablation. J Interv Card Electrophysiol 2024; 67: 479–492.
• 10.   Kawaji T, Shizuta S, Aizawa T, Nishiwaki S, Yoshizawa T, Nishiuchi S, et al. Prognostic importance of B-type natriuretic peptide level in patients undergoing catheter ablation for atrial fibrillation. Circ J 2023; 87: 1730–1739.
• 11.   Jiang H, Wang W, Wang C, Xie X, Hou Y. Association of pre-ablation level of potential blood markers with atrial fibrillation recurrence after catheter ablation: A meta-analysis. Europace 2017; 19: 392–400.
• 12.   Iwahashi N, Gohbara M, Kirigaya J, Abe T, Horii M, Hanajima Y, et al. Prognostic significance of the combination of left atrial reservoir strain and global longitudinal strain immediately after onset of ST-elevation acute myocardial infarction. Circ J 2022; 86: 1499–1508.
• 13.   Kawakami H, Ramkumar S, Pathan F, Wright L, Marwick TH. Use of echocardiography to stratify the risk of atrial fibrillation: Comparison of left atrial and ventricular strain. Eur Heart J Cardiovasc Imaging 2020; 21: 399–407.
• 14.   Bhat A, Gan GCH, Chen HHL, Khanna S, Mahajan V, Gupta A, et al. Left atrial reservoir strain is a superior discriminator of cardioembolism in ischaemic stroke. Eur Heart J Imaging Methods Pract 2024; 2: qyae022.
• 15.   Knappe D, Vogler J, Weimann J, Banas V, Obergassel J, Yildirim S, et al. Left atrial reservoir strain and recurrence of atrial fibrillation following de-novo pulmonary vein isolation: Results of the ASTRA-AF pilot study. Circ J 2025; 89: 153–161.