Response to Letter by Wong et al
We thank Drs Wong and Poon for their interest in our article entitled “Matrix detachable coils for the endovascular treatment of intracranial aneurysms.”1 They have calculated the rate of thrombus formation in our series of 25 patients treated with matrix detachable coils and compared it to a series of 210 patients treated with bare platinum coils.2 The thrombus formation rate was 20% in the matrix series and 4.3% in the series of patients treated with bare platinum coils. This difference was statistically significant in the Fisher exact test (P=0.009).
They raise a number of points to which we have the following responses. Our patients were treated under full heparinization, and intravenous heparin was maintained for 48 hours after treatment. We are not aware of any contributing factor that might explain the potentially elevated rate of thrombus formation in our matrix series. There was no case of coil protrusion into the parent artery, and the number of balloon remodelling procedures did not exceed the usual average.
For their comparison, Drs Wong and Poon chose the series of Workman et al with one of the lowest rates of thromboembolic complications published in the literature.2 We have reviewed 4 additional series published between 1999 and 2003 of patients treated with bare platinum coils including up to 1383 patients.3–6 The reported rate of thromboembolic complications in these series was rather variable and lied between 4.4% to 8.5%. With respect to the small number of patients included in our survey, we refrained from drawing any conclusions concerning the rate of thromboembolic complications we have observed with matrix coils.
Taschner CA, Leclerc X, Rachdi H, Barros AM, Pruvo JP. Matrix detachable coils for the endovascular treatment of intracranial aneurysms: analysis of early angiographic and clinical outcomes. Stroke. 2005; 36: 2176–2180.
Workman MJ, Cloft HJ, Tong FC, Dion JE, Jensen ME, Marx WF, Kallmes DF. Thrombus formation at the neck of cerebral aneurysms during treatment with Guglielmi detachable coils. AJNR Am J Neuroradiol. 2002; 23: 1568–1576.
Brilstra EH, Rinkel GJ, van der Graaf Y, van Rooij WJ, Algra A. Treatment of intracranial aneurysms by embolization with coils: a systematic review. Stroke. 1999; 30: 470–476.
Ng P, Khangure MS, Phatouros CC, Bynevelt M, ApSimon H, McAuliffe W. Endovascular treatment of intracranial aneurysms with Guglielmi detachable coils: analysis of midterm angiographic and clinical outcomes. Stroke. 2002; 33: 210–217.
Friedman JA, Nichols DA, Meyer FB, Pichelmann MA, McIver JI, Toussaint LG 3rd, Axley PL, Brown RD Jr. Guglielmi detachable coil treatment of ruptured saccular cerebral aneurysms: retrospective review of a 10-year single-center experience. AJNR Am J Neuroradiol. 2003; 24: 526–533.