Author + information
- Luigi Di Biase, MD, PhD,
- Pasquale Santangeli, MD,
- Fiorenzo Gaita, MD and
- Andrea Natale, MD⁎ ()
- ↵⁎Texas Cardiac Arrhythmia Institute, St. David's Medical Center, 3000 N. I-35, Suite 720, Austin, Texas 78705
We welcome the comments by Dr. Ren and colleagues because they provide an occasion to reiterate several key points from our study that we suspect have been missed.
The main criticism raised by Ren et al. is that the left atrial appendage (LAA) morphology classification adopted in our study is “impractical and complicated.” Although the scientific validity of such subjective statements is highly questionable, we would like to point out that the results of the formal interobserver agreement test (provided in the original paper) clearly refute the arguments by Dr. Ren and colleagues Indeed, different LAA morphologies were correctly classified by different and blinded investigators with a high level of agreement (1).
In addition, since the classification Chicken Wing/non-Chicken Wing is very simple and practical, and since the results are confirmed while sorting between these 2 variables (Fig. 6), we wonder why the authors question the complexity of the analysis (1).
Moreover, the LAA morphology classification is derived from previous studies by our group (2) and others (3–6), in which different LAA morphologies were defined in an unselected cohort of atrial fibrillation (AF) patients.
The authors suggest that intracardiac echocardiography (ICE) can provide detailed imaging of the LAA. Again, such a statement is not supported by any published evidence and therefore remains, in our view, a purely subjective assertion. Of note, Dr. Ren and colleagues correctly point out that the LAA is typically formed by several different lobes “which might not be in the same plane.” With these premises, it is highly unlikely that a 2-dimensional imaging technique such as ICE would be of any value in studying the complex 3-dimensional LAA morphology (7).
In addition, ICE is an invasive approach and therefore less practical than computed tomography or magnetic resonance imaging.
Dr. Ren and colleagues also question the etiology of the strokes in our study, stating that “LAA thrombus is [only] a possible cause” of stroke in AF patients and that “cardiac vegetation, valvular disease, dilated cardiomyopathy, atrial septal aneurysm, atrial septal defect, patent foramen ovale, as well as aortic atheroma and cerebral vascular disease” are “more naturally related to the history of stroke.” Unfortunately, the validity of such statements has been already rejected by multiple studies on AF patients with stroke, which have consistently reported LAA thromboembolism as the dominant etiology of stroke in these patients (8).
On the other side, we also wish to clarify that other causes of strokes were adequately excluded in these patients at the time of the event with appropriate tests.
In closing, we agree with Dr. Ren and colleagues that statistical correlation does not imply causation, and an adequately prospective study is warranted to confirm whether thromboembolism from non-Chicken Wing LAA is a frequent cause of stroke in patients with AF—as the results of our study might suggest—or whether “cardiac vegetation, valvular disease, atrial septal aneurysm, atrial septal defect, patent foramen ovale, aortic atheroma” are the predominant cause of stroke in AF patients, as Dr. Ren and colleagues claim.
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- ICE-CHIP Investigator Study Group