| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
German Heart Center Munich, Lazarettstrasse 36, Munich D-80636, Germany
(Email: hettich{at}dhm.mhn.de).
We read with great interest the article by Fritzsche and colleagues [1] in which their experience with a new home monitoring device (ThromboCheck, CardioSignal GmbH, Hamburg, Germany) for the early detection of mechanical valve dysfunction is presented. We agree with the authors that the management of patients after mechanical valve replacement should be improved because of the risk of thromboembolic complications in these patients.
ThromboCheck devices (CardioSignal GmbH) were handed out to 483 patients after mechanical heart valve replacements. In 26 patients whose device showed a warning message, morphologic correlations were searched using imaging techniques. Imaging techniques revealed 25 true-positive and 1 false-positive measurement.
In our opinion there is a fundamental problem with the conclusion reached by the authors. The authors claim a sensitivity of 100% and a specificity of 99.8% of the ThromboCheck device. However, the authors do not reveal how many of the 457 patients with unsuspicious phonocardiogram may have shown a false-negative result. Because prosthetic valve thrombosis may obviously occur undetected by the patient, the investigation by a questionnaire is not sufficient to demonstrate a sensitivity of 100%. The study shows the positive predictive value of the method, but not its sensitivity or specificity. To give a statement concerning sensitivity and specificity, the 457 patients with unsuspicious phonocardiogram should have been examined in the same way as the patients with suspicious phonocardiogram (ie, with fluoroscopy), because the authors revealed that clinical and echocardiographic follow-up is not sufficient.
Furthermore, it seems hard to accept (assuming sufficient sonic conditions) that transthoracic echocardiography (TTE) was "not suspicious" in 5 of 25 cases (20%) in which fluoroscopy detected occluder malfunction. We are aware of the difficulty in assessing mechanical valve prostheses by echocardiography. However, if the sonic conditions were bad in these patients, then the echocardiographer should not have stated that "TTE [was] not suspicious," but that TTE was not of adequate quality. Did the echocardiographers re-evaluate the echocardiograms after the diagnosis of a valve dysfunction by fluoroscopy? Perhaps there are discrete signs of valve dysfunction that would be helpful to know for other echocardiographers so as to increase the detection rate of valve dysfunction by echocardiography.
We believe that the home monitoring device could be a very valuable tool to improve the management of patients with mechanical heart valves. It even has the potential to detect intermittent valve dysfunction [2], but as a result of this study there is still uncertainty concerning sensitivity and specificity of the method. Therefore, it seems too early "to have it included in the guidelines of cardiological and cardiosurgical associations for the care of heart valve patients" as recommended by the authors.
 |
References |
|---|
 Top References |
|---|
Related Article
This article has been cited by other articles:
|
|
 |
|
  D. Fritzsche Reply Ann. Thorac. Surg., March 1, 2008; 85(3): 1143 - 1143. [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
