Response to Letter by Gill et al
We are grateful to colleagues Gill et al for their comments. We fully agree that the reported prevalence of left atrial appendage thrombus (38/231, 16%) in our series of patients with previous TIA or stroke is relatively, and surprisingly, high. The patients included are an unselected series of consecutive patients with TIA or stroke, in whom no absolute indication for anticoagulation was found after standardized work-up, 12-lead ECG and cardiac history included. It may be hypothesized that some patients had paroxysmal atrial fibrillation, which may predispose to formation of left atrial appendage thrombus. In addition, patients with spontaneous contrast were not excluded from the series, and the prevalence of left atrial appendage thrombus is higher in these patients.
In addition, left atrial appendage thrombus may be present in more patients with stroke and sinus rhythm than previously reported. Recently, Ling et al reported in 11% of elderly stroke patients (≥50 years of age) with normal sinus rhythm, left atrial appendage thrombus or spontaneous echocardiographic contrast.1 Possibly, the use of multiplane TEE probes (as compared with mono- and biplane probes) and modern echocardiographic technology has increased image quality, which may play an additional role in the enhanced detection of left atrial appendage thrombi.
On the other hand the prevalence of patent foramen ovale (PFO) in the current series was relatively low. PFO-prevalence in the general population is reported in about 20%, also depending on diagnostic criteria. It is well agreed that cerebral ischemia is seldom caused by paradoxical embolism from the right to left side of the heart. Therefore, although common, the clinical relevance of PFO in stroke patients is controversial and probably minimal.2 For this reason, we have only reported clinically meaningful PFOs, defined as passage of a cloud of bubbles or intense opacification of the left atrium after successful Valsalva maneuver. Thus, PFOs were not reported if shunting was slight to moderate, and this may explain the relatively low prevalence of PFOs in the current study. Further studies are needed to fully elucidate these issues.
Ling J, Hirono O, Okuyama H, Takeishi Y, Kayama T, Kubota I. Ratio of peak early to late diastolic filling velocity of the left ventricular inflow is associated with left atrial appendage thrombus formation in elderly patients with acute ischemic stroke and sinus rhythm. J Cardiol. 2006; 48: 75–84.
Warlow CP, Dennis MS, Gijn van J, Hankey GJ, Sandercock PAG, Bamford JM, Wardlaw JM. Stroke - A Practical Guide to Management. 2001; Blackwell Science Ltd.