Although the true pathophysiologic mechanisms underlying the different LAA flow patterns in nonrheumatic AF have not been defined, several factors of potential importance should be mentioned. First, the left atrial size was found to be larger in patients with lower LAA blood flow. As an integral part of the left atrium, the LAA movement may be functionally compromised by left atrial dilatation. However, this still needs further confirmation. Second, LAA dilatation was found to be associated with low LAA blood flow and poor LAA function in previous reports. In the current study, however, we found no such association. The LAA maximal area was not different between the two groups. The reason for these differing results is uncertain, but it may be related to the exclusion of patients with rheumatic AF from our study. Thus, LAA size may not be an important factor in determining LAA flow and function in patients with nonrheumatic AF. my canadian pharmacy phone number
The reported prevalence of TEE-detected left atrial SEC in patients with nonrheumatic AF ranged from 24.3 percent to 47 percent. The prevalence of left atrium and/or LAA thrombus was about 6.8 percent to 19 percent. In the current study, 31 percent of patients with nonrheumatic AF were found to have left atrium LAA/SEC and 10.3 percent patients had LAA thrombus. The different prevalence rates of reported series in comparison to ours may be related to the different patient selection.
In our series, patients with nonrheumatic AF with low LAA blood flow pattern tended to have higher prevalence of left atrium LAA/SEC formation. Left atrial SEC had been shown to be an independent predictor of thromboembolism in patients with mitral valve disease and to be a marker of previous thromboembolism in patients with nonvalvular AF. While not demonstrated, patients with a low LAA blood flow pattern may be at higher risk for systemic embolization. Several recent clinical trials have demonstrated the marked efficacy of warfarin in preventing stroke in patients with nonrheumatic AF. Although they showed that warfarin therapy could be quite safe if monitored carefully, bleeding risk still existed. Thus, characterization of subgroups of patients with nonrheumatic AF with higher rate of systemic embolism helps us to decide which patients should receive anticoagulation treatment. In the Stroke Prevention in AF study, three clinical and two echocardiographic markers were defined as risk factors for thromboembolism in patients with nonrheumatic AF.