Circulation Journal
Online ISSN : 1347-4820
Print ISSN : 1346-9843
ISSN-L : 1346-9843
Letters to the Editor
Catheter Ablation of Atrial Fibrillation and Thromboembolic Risk
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Masateru TakigawaAtsushi TakahashiTaishi KuwaharaKenzo HiraoMitsuaki Isobe
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2015 Volume 79 Issue 2 Pages 445-

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We thank Dr Kornej and coworkers for their interest in our paper and for raising important issues.

Regarding the follow-up accuracy, annual telephone interviews with the patients and their families were conducted to confirm each patient’s hospitalization history for each year during our study.1 Thus, we are certain that we did not miss any patients with symptomatic thromboembolism (TE) who required hospitalization during the follow-up period. However, patients with transient ischemic attacks may have been missed if they did not visit a neurologist because of distance or timing reasons, did not visit a hospital because of symptom resolution, or if the attending physician deemed the symptom(s) sufficiently minor to make hospitalization unnecessary.

We understand that the new European Society of Cardiology guidelines (2010) recommend the use of the CHA2DS2-VASc score to complement initial assessments using the CHADS2 score.2 The CHA2DS2-VASc score is more inclusive of common stroke risk factors seen in everyday clinical practice, and an increasing number of studies support its use.3,4 However, unfortunately, we did not collect all relevant data to allow determination of the CHA2DS2-VASc score during this study because the guideline published in 2006 had recommended the use of the CHADS2 score.5 In contrast to previous studies regarding post-catheter ablation (CA) strokes, however, we performed detailed examinations of the 11 individuals who developed TE in the present study. Among them, 3 patients exhibited CHADS2 score ≤1 and 2 of those individuals showed CHA2DS2-VASc scores ≥2, one of them reaching a CHADS2 score of 2 and a CHA2DS2-VASc score of 3 at the time of the TE because she was over 75 years old. The remaining patient developed TE 4 years after the CA, at age 63 years, despite demonstrating low risk on both the CHADS2 (=0) and CHA2DS2-VASc (=0) score. However, this patient had underlying valvular heart disease.

Despite the utility of scoring systems such as the CHADS2 and CHA2DS2-VASc, conditions specific to each individual also have to be taken into account, because tailor-made therapy may be important to the follow-up of post-CA atrial fibrillation (AF) patients. Hence, the TE risk should be reassessed as patients get older. Furthermore, in addition to the scores, each patient’s background should be carefully considered; for example, patients with cardiomyopathy,6,7 amyloidosis,8 low left atrial appendage flow velocity or spontaneous echo contrast on transesophageal echocardiography7,9 may have additional risks, even if they are in a lower risk group according to the scoring system. Moreover, the evidence of the value of these scoring systems for stroke risk stratification in patients with valvular heart disease has not been established.10

In addition, we should be very careful when discussing the post-CA predictors of TE. Although several factors are associated with late-phase TE, a low stroke incidence may decrease the statistical power and the results could easily change. AF recurrence, as a specific associated factor, should be dealt with carefully because the determination of AF recurrence itself is a limitation of AF ablation studies. AF recurrence may depend on the original type of AF (paroxysmal, persistent, or long-standing persistent), the presence or absence of symptoms or medications, or the follow-up protocol. As well as Dr Kornej, we believe that AF recurrence might be an important predictor of late-phase TE, despite the weak statistical power of our study.1 However, further investigations involving large study populations and long and thorough follow-up are required to arrive at a definitive conclusion regarding this issue.

Several studies have suggested that high-risk patients, categorized using risk scores, require optimized anticoagulation with intensified oral anticoagulation and/or intensified rhythm control. However, the optimized management for low-risk patients remains unknown and further studies are needed to elucidate these issues, as Dr Kornej mentioned.

Disclosures

None.

  • Masateru Takigawa, MD
  • Atsushi Takahashi, MD
  • Taishi Kuwahara, MD
  • Kenzo Hirao, MD
  • Mitsuaki Isobe, MD
  • Cardiovascular Center, Yokosuka Kyosai Hospital, Yokosuka (M.T., A.T., T.K.);
  • Heart Rhythm Center, Tokyo Medical and Dental University, Tokyo (K.H.);
  • and Department of Cardiovascular Medicine, Tokyo Medical and Dental University, Tokyo (M.T., M.I.), Japan

(Released online January 7, 2015)

References
 
© 2015 THE JAPANESE CIRCULATION SOCIETY
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