Published online before print December 11, 2003, doi: 10.1161/01.STR.0000108266.11282.BF
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(Stroke. 2004;35:156.)
© 2004 American Heart Association, Inc.
Original Contributions |
Editorial Comment—The MOST Score: Modifying the Open-Artery "Good"–Closed-Artery "Bad" Approach to Thrombolysis Prognosis
Department of Neurology, Ochsner Foundation Clinic and Hospital, New Orleans, Louisiana
The rapidity and degree of recanalization has been shown to predict good outcome in thrombolysis of acute ischemic stroke.1,2 However, despite complete recanalization, many patients continue to do poorly. Some never recover function, while others experience deterioration after improvement3 or symptomatic intracerebral hemorrhage. Conversely, many patients experience complete recovery despite continued vessel obstruction. Several clinical factors have been shown to predict poor outcome including continued arterial occlusion, slow recanalization, hyperglycemia, systolic hypertension, and early ischemic changes on the baseline CT scan.4,5
In this report, Molina et al prospectively collected patients who presented with acute stroke syndromes with transcranial Doppler (TCD)-demonstrated middle cerebral artery occlusions and were treated using standard intravenous tissue plasminogen activator (tPA) protocols.6 Hemodynamic, radiologic, laboratory, and clinical data were examined, and 5 variables were found to be associated with good outcome (defined as a modified Rankin Scale score 
2). These 5 variables (degree of recanalization, site of occlusion, early ischemic CT scan changes, severity of clinical presentation, and presence of moderate hypertension) were then assigned values as part of the scoring tool to predict outcome (the MOST [Multimodal Outcome Score for Stroke Thrombolysis] score).
In line with previous reports, the authors found that presence of recanalization had the strongest predictive value (OR, 4.11; P<0.001). Interestingly, 25% of patients without recanalization experienced a good outcome. Early ischemic changes on CT as measured by the Alberta Stroke Programme Early CT Score (ASPECTS) were found to be highly predictive as well (OR, 2.98; P=0.0253). These findings suggest that the strategy of rapid intervention with a goal of recanalization via intravenous or catheter-driven therapy is a valid one. However, no degree of flow restoration will bring back irreversibly damaged tissue possibly evidenced by early CT changes.7
The most intriguing finding is the variable of systolic blood pressures >150 leading to poor outcome. All of these patients would have had systolic blood pressures <185 and diastolic blood pressures <110 as part of the standard intravenous-tPA therapy guidelines.8 Outlier hypertensives would have been excluded. The role of blood pressure in stroke outcome is controversial.9 The results of the Acute Candesartan Cilexetil Therapy in Stroke Survivors (ACCESS) trial10 and post-hoc analysis of the Heart Outcomes Prevention Evaluation (HOPE) stroke population11 complicates this issue. Certainly, the question is out there—should we be actively lowering blood pressure in acute stroke? A well-designed trial is clearly needed.
There are some limitations to this study. The MOST score was derived by dichotomizing several variables such as degree of recanalization, systolic blood pressure, ASPECTS, and NIHSS in a manner that best enhances the effect for each criterion. Are these results as important when evaluating as continuous variables? All patients had TCD-determined occlusions in the middle cerebral artery territory. No consensus statement can be made about other arterial territories or the frequent patient who has no thrombus found. Long-term data were gathered by telephone in some cases, adding a variable to the quality of information. Finally, many of these patients received continuous TCD monitoring, which has been suggested to speed clot lysis and may have spuriously improved recanalization rates in this cohort.
How does this trial affect clinical practice? Many factors pointed out by the MOST score are already generally recognized as leading to poor outcome. Patients with large strokes, significant early ischemic changes on CT, and a large clot burden will do poorly in general, and these baseline characteristics cannot be altered. This leaves rapid recanalization and blood pressure as potential targets for therapy. The MOST score’s primary role is as a predictive and research tool. It may be useful to be able to offer an evidence-based prognostic assessment to families at the bedside following thrombolytic therapy. As pointed out by the authors, withholding intravenous tPA based on the MOST criteria is not advised.
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1. Christou I, Alexandrov AV, Burgin WS, Wojner AW, Felberg RA, Malkoff M, Grotta JC. Timing of recanalization after tissue plasminogen activator therapy determined by transcranial Doppler correlates with clinical recovery from ischemic stroke. Stroke. 2000; 31: 1812–1816.
2. Felberg RA, Okon NJ, El-Mitwalli A, Burgin WS, Grotta JC, Alexandrov AV. Early dramatic recovery during intravenous tissue plasminogen activator infusion: clinical pattern and outcome in acute middle cerebral artery stroke. Stroke. 2002; 33: 1301–1307.
3. Alexandrov AV, Felberg RA, Demchuk AM, Christou I, Burgin WS, Malkoff M, Wojner AW, Grotta JC. Deterioration following spontaneous improvement: sonographic findings in patients with acutely resolving symptoms of cerebral ischemia. Stroke. 2000; 31: 915–919.
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9. Brott T, Lu M, Kothari R, Fagan SC, Frankel M, Grotta JC, Broderick J, Kwiatkowski T, Lewandowski C, Haley EC, et al. Hypertension and its treatment in the NINDS rt-PA Stroke Trial. Stroke. 1998; 29: 1504–1509.
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11. Bosch J, Yusuf S, Pogue J, Sleight P, Lonn E, Rangoonwala B, Davies R, Ostergren J, Probstfield J. HOPE Investigators: Use of ramipril in preventing stroke: double blind randomised trial: Heart Outcomes Prevention Evaluation. BMJ. 2002; 324: 699–702.
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