Thrombolysis of Basilar Artery Occlusion—Intra-Arterial or Intravenous: Is There Really No Difference?
To the Editor:
With great interest we read the meta-analysis on the therapy of basilar artery occlusion (BAO) by Lindsbergh and Mattle1 published in the March issue of Stroke. The authors compared the pooled data from 13 retrospective studies (3 studies including 76 patients treated by intravenous thrombolysis [IVT], and 10 studies including 344 patients treated by intra-arterial thrombolysis [IAT]) in patients with BAO. The authors draw the conclusions that the route of drug delivery for treatment of BAO does not make a difference in clinical outcome and that the odds for survival without a handicap improve equally after IVT and IAT. We agree with the authors that the recanalization success is the conditio sine qua non for a favorable neurological outcome in BAO.1,2
The conclusions, however, raise some concerns. As stated by the authors,1 the recanalization rate of IVT is only 53%, probably owing to the unselective way of delivery and large thrombus load in extended BAO. The recanalization rate of IAT is reported to be 65%.1 The endovascular approach, however, offers besides IAT with a recanalization rate up to 74%2 the opportunity of mechanical recanalization. Preliminary results have shown recanalization rates up to 100% and favorable clinical outcome (ie, independence in daily life) in up to one-third of the patients by using different devices for mechanical recanalization alone or in combination with IAT.3 Furthermore, high-grade arteriosclerotic stenosis of the extra- and intracranial vertebrobasilar circulation is a frequent etiology of BAO and a common cause of early reocclusion after thrombolysis. Thus, the IA approach allows for simultaneous acute treatment of the BAO and prevention of early reocclusion of the basilar artery by percutaneous transluminal angioplasty with or without stenting.
Fifty of 76 patients treated by IVT were derived from Lindsberg’s own study published in JAMA in 2004.4 In this study, BAO has been diagnosed by the clinical syndrome combined with time-of-flight MR angiography performed on a 1.5-T scanner. Intra-arterial angiography was available in only 5 of 50 patients. It is well known that MR angiography including raw images is insensitive to slow and low residual flow and may show discontinuity (skip sign) attributable to technical reasons.5 Therefore, it remains ambiguous whether the basilar artery was completely or only partially occluded with a potentially life-saving residual flow maintaining the perfusion of the brain stem in the patients of Lindsberg’s study. Consequently, a potential bias of this pivotal study, which has driven the results of the IVT group, might have introduced a bias into the meta-analysis.
From our point of view, the IA approach used for highly selective thrombolysis or mechanical recanalization remains the therapy of first choice in BAO. The primary IV use of glycoprotein IIb/IIIa receptor inhibitors or recombinant tissue plasminogen activator may be helpful for bridging the interval until referral to an experienced neurointerventional stroke center as suggested by Eckert et al.6 To compare the efficacy of the primary IA approach and the combined IV and IA approach (bridging concept) a randomized controlled trial is needed. Angiographic and clinical variables such as thrombus volume, collateral pathways, additional stenoses of the vertebrobasilar system, as well as the standardized evaluation of the neurological status before and after treatment and hemorrhagic and ischemic complications have to be considered in the study protocol of such a prospective trial.
Lindsberg PJ, Mattle HP. Therapy of basilar artery occlusion: a systematic analysis comparing intra-arterial and intravenous thrombolysis. Stroke. 2006; 37: 922–928.
Schulte-Altedorneburg G, Hamann GF, Mull M, Kühne D, Liebetrau M, Weber W, Brückmann H, Mayer TE. Intraarterial thrombolysis in acute vertebrobasilar occlusions: a multicentric retrospective analysis of 180 cases. Am J Neuroradiol. 2006; In press.
Mayer TE, Hamann GF, Schulte-Altedorneburg G, Brückmann H. Treatment of vertebrobasilar occlusion by a Coronary Waterjet Thrombectomy Device–a Pilot Study. Am J Neuroradiol. 2005; 26: 1389–1394.
Eckert B, Koch C, Thomalla G, Kucinski T, Gryzska U, Roether J, Alfke K, Jansen O, Zeumer H. Aggressive therapy with intravenous abciximab and intra-arterial rtPA and additional PTA/stenting improves clinical outcome in acute vertebrobasilar occlusion. Combined local fibrinolysis and intravenous abciximab in acute vertebrobasilar stroke treatment (FAST) – Results of a multicenter study. Stroke. 2005; 36: 1160–1165.