CORRESPONDENCE: LETTER TO THE EDITOR
Is Thrombus Aspiration the Appropriate "Remedy"?
Matthew I. Worthley, MBBS, PhD, FACC* and
Stephen G. Worthley, MBBS, PhD, FACC
* Royal Adelaide Hospital, Department of Medicine, North Terrace, Adelaide, South Australia 5000, Australia (Email: matthew.worthley{at}adelaide.edu.au).
The recently published substudy of the REMEDIA (Randomized Evaluation of the Effect of Mechanical Reduction of Distal Embolization by Thrombus-Aspiration in Primary and Rescue Angioplasty) trial by Galiuto et al. (1) raises a number of important issues regarding routine use of thrombectomy devices in the setting of acute ST-segment elevation myocardial infarction. To date, results from recently published larger randomized studies of distal protection have shown a neutral effect (2–4). Furthermore, relevant results were obtained in 2 of these studies regarding an associated increase in infarct size (3,4).
The original REMEDIA trial (5), however, showed improved myocardial blush grade and ST-segment resolution in the thrombectomy arm. The Galiuto et al. (1) substudy of this trial further evaluates potential mechanisms behind this finding. In this substudy, patients were evaluated with myocardial contrast echocardiography (MCE) at 24 h, 1 week, and 6 months, with consistent improvements seen over these time periods, not only in microvascular but also myocardial function. These results, though promising, should be viewed in light of not only the previously published neutral studies, but also the PROMISE (Protection Devices in PCI Treatment of Myocardial Infarction for Salvage of Endangered Myocardium) study (6).
Utilizing Doppler Flo-wire and cardiac magnetic resonance imaging evaluation, the PROMISE study had neutral findings regarding microvascular function and infarct size. Differences between the Galiuto et al. (1) and PROMISE (6) studies are important to note, particularly when evaluating their different conclusions. It is possible that the microvascular circulation following primary angioplasty remains dysfunctional in the short term but begins to normalize over 12 to 24 h. This would explain both the immediate postangioplasty neutral result of the Doppler Flo-wire study and positive results of the MCE evaluation over time. Furthermore, it is possible that initial passage of a distal protection device (i.e., filter wire or distal balloon occlusion device) may result in distal embolization, a process that might be reduced with isolated thrombectomy catheter use.
However, the major concern relates to the Galiuto et al. (1) study being potentially underpowered. As no power calculations were provided in this trial, we are unable to assess whether 50 patients is appropriate; of note, the negative PROMISE study randomized 4 times more subjects.
Although the findings of the small Galiuto et al. (1) study are promising, the weight of evidence of larger randomized trials supports a neutral effect of distal protection on both microvascular and myocardial function. Further evaluation of such devices is imperative, particularly in selected cases such as those with large angiographic thrombus burden.
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1. Galiuto L, Garramone B, Burzotta F, et al. Thrombus aspiration reduces microvascular obstruction after primary coronary intervention: a myocardial contrast echocardiography substudy of the REMEDIA trial J Am Coll Cardiol 2006;48:1355-1360.[Abstract/Free Full Text]2. Stone GW, Webb J, Cox DA, et al. Distal microcirculatory protection during percutaneous coronary intervention in acute ST-segment elevation myocardial infarction: a randomized controlled trial JAMA 2005;293:1063-1072.[Abstract/Free Full Text] 3. Ali A, Cox D, Dib N, et al. AIMI Investigators Rheolytic thrombectomy with percutaneous coronary intervention for infarct size reduction in acute myocardial infarction: 30-day results from a multicenter randomized study J Am Coll Cardiol 2006;48:244-252.[Abstract/Free Full Text] 4. Kaltoft A, Bottcher M, Nielsen SS, et al. Routine thrombectomy in percutaneous coronary intervention for acute ST-segment-elevation myocardial infarction: a randomized, controlled trial Circulation 2006;114:40-47.[Abstract/Free Full Text] 5. Burzotta F, Trani C, Romagnoli E, et al. Manual thrombus-aspiration improves myocardial reperfusion: the randomized evaluation of the effect of mechanical reduction of distal embolization by thrombus-aspiration in primary and rescue angioplasty (REMEDIA) trial J Am Coll Cardiol 2005;46:371-376.[Abstract/Free Full Text] 6. Gick M, Jander N, Bestehorn HP, et al. Randomized evaluation of the effects of filter-based distal protection on myocardial perfusion and infarct size after primary percutaneous catheter intervention in myocardial infarction with and without ST-segment elevation Circulation 2005;112:1462-1469.[Abstract/Free Full Text]
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- Francesco Burzotta, Filippo Crea, and Leonarda Galiuto
J. Am. Coll. Cardiol. 2007 49: 1671.
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