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(Stroke. 2008;39:3015.)
© 2008 American Heart Association, Inc.
Original Contributions |
From the St Michaels Hospital Division of Neurosurgery (R.L.M.), Keenan Research Centre and the Li Ka Shing Knowledge Institute of St Michaels Hospital and Department of Surgery, University of Toronto, Toronto, Ontario, Canada; the University of Virginia (N.F.K.), Charlottesville, Va; Columbia University (S.M.), New York, NY; University Hospitals of Geneva (D.R.), Geneva, Switzerland; the University of Mannheim (P.S.), Mannheim, Germany; the University of Frankfurt (S.W.), Frankfurt, Germany; Actelion Pharmaceuticals (A.F., S.R.), Basel, Switzerland; and Ospedale Civile Maggiore di Verona (A.P.), Verona, Italy.
Correspondence to R. Loch Macdonald, MD, PhD, Keenan Endowed Chair and Head, Division of Neurosurgery, St Michaels Hospital, 30 Bond Street, Toronto, Ontario, Canada, M5B 1W8. E-mail macdonaldlo{at}smh.toronto.on.ca
| Abstract |
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Methods— Patients (n=413) were randomized to placebo or clazosentan beginning within 56 hours and continued up to 14 days after initiation of treatment. The primary end point was moderate or severe angiographic vasospasm based on centrally read, blinded evaluation of digital subtraction angiography at baseline and 7 to 11 days postsubarachnoid hemorrhage. A morbidity/mortality end point, including all-cause mortality, new cerebral infarct from any cause, delayed ischemic neurological deficit due to vasospasm, or use of rescue therapy, was evaluated by local assessment. Clinical outcome was assessed by the extended Glasgow Outcome Scale at 12 weeks.
Results— Moderate or severe vasospasm was reduced in a dose-dependent fashion from 66% in the placebo group to 23% in the 15 mg/h clazosentan group (risk reduction, 65%; 95% CI, 47% to 78%; P<0.0001). No significant effects were seen on secondary end points. Post hoc analysis using a centrally assessed morbidity/mortality end point that included death and rescue therapy but only cerebral infarcts and delayed ischemic neurological deficit due to vasospasm on central review showed a trend toward improvement with clazosentan (37%, 28%, and 29% in the 1, 5, and 15 mg/h groups versus 39% in the placebo group, nonsignificant). Clazosentan was associated with increased rates of pulmonary complications, hypotension, and anemia.
Conclusions— Clazosentan significantly decreased moderate and severe vasospasm in a dose-dependent manner and showed a trend for reduction in vasospasm-related morbidity/mortality in patients with aneurysmal subarachnoid hemorrhage when centrally assessed. Overall, the adverse effects were manageable and not considered serious.
Key Words: cerebral infarction outcome subarachnoid hemorrhage vasospasm
| Introduction |
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Endothelin is a potent, long-lasting endogenous vasoconstrictor that has been implicated in the pathogenesis of vasospasm.6,7 Endothelin concentrations may be increased in the cerebrospinal fluid and there is increased sensitivity of the cerebral arteries to endothelin after SAH. Endothelin receptor antagonists reduce experimental vasospasm.7–10 Specifically, clazosentan, a nonpeptide endothelin receptor A antagonist, reduced vasospasm after experimental SAH.11,12 A Phase 2a blinded, placebo-controlled trial in 34 patients with SAH undergoing aneurysm surgery reported that clazosentan significantly reduced the incidence and severity of angiographic vasospasm.13 This result led us to conduct CONSCIOUS-1, a larger trial designed to identify the safest and most effective dose of clazosentan for prevention of angiographic cerebral vasospasm in patients with SAH undergoing clipping or coiling of a ruptured aneurysm.
| Patients and Methods |
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Study Population
Eligible patients were 18 to 70 years old with aneurysmal SAH due to a ruptured saccular aneurysm confirmed by digital subtraction catheter angiography (DSA). SAH had to be diffuse (long axis
20 mm) or localized (long axis <20 mm) thick (short axis
4 mm) subarachnoid clot on CT scan within 48 hours of SAH. Patients had a World Federation of Neurological Surgeons Grade 1 to 4 on admission or were Grade 5 patients who had improved to Grade 4 or less after resuscitation and ventriculostomy.14
Exclusion criteria were: (1) SAH from a lesion other than a ruptured saccular aneurysm; (2) intraventricular or intracerebral blood in the absence of localized thick or diffuse SAH; (3) no or localized thin SAH on CT; (4) cerebral vasospasm on admission DSA; (5) hypotension (systolic blood pressure
90 mm Hg) refractory to fluid therapy; (6) neurogenic pulmonary edema or cardiac failure requiring inotropic support; (7) severe or unstable concomitant condition or disease or chronic condition, which, in the opinion of the investigator, could affect assessment of the safety or efficacy of the study drug; (8) kidney (plasma creatinine
177 µmol/L) and/or liver disease (total bilirubin >51.3 µmol/L); and (9) prior cerebral damage on CT scan such as stroke (>2 cm maximum diameter), traumatic brain injury, previously treated cerebral aneurysm, arterial venous malformation, or pre-existing cerebrovascular disorder that would affect diagnosis and evaluation of SAH. Women of childbearing potential had negative pretreatment serum pregnancy tests.
Study Interventions
Placebo or clazosentan was started intravenously within 56 hours of SAH and continued for 14 days. Aneurysmal clipping or coiling was performed before or within 12 hours after initiation of treatment. Oral nimodipine (60 mg every 4 hours) and intravenous fluids of
3 L/day were recommended. If symptomatic vasospasm was diagnosed, the investigators initiated treatment, which could include induced hypertension, hypervolemia, hemodilution, and endovascular balloon dilation or vasodilator infusion. Prophylactic intravenous nimodipine, nicardipine, magnesium, other endothelin receptor antagonists, antifibrinolytics, or intrathecal thrombolytics were prohibited.
Clinical Assessments and Radiology
All patients had baseline DSA within 48 hours of SAH before the aneurysm-securing procedure and on day 9 ± 2 postaneurysm rupture. DSA also was performed if patients showed signs of symptomatic vasospasm at any time unless vasospasm had already occurred and there was no other medical indication for DSA. CT scan was performed on admission within 48 hours of SAH, 24 to 48 hours after the aneurysm-securing procedure, 6 weeks after SAH, and whenever there was neurological worsening. The images were submitted to Perceptive and reviewed centrally by 2 independent, blinded reviewers. CT scans were assessed for SAH using the Hijdra scale,15 hydrocephalus by ventriculocranial ratio,16 volume of intracerebral hemorrhages and hypodense areas quantified by planimetric analysis, intraventricular hemorrhage by the Graeb scale,17 and presence or absence of midline shift and extraaxial hematoma. The diameters of proximal cerebral arteries were measured on DSA and corrected for magnification using metal rings of known diameter that were taped to the scalp during DSA or by measuring diameters of the extracranial arteries.18,19 Vasospasm was quantified as the percent reduction in arterial diameter between baseline and day 9±2 DSA. A global assessment of vasospasm was then made and classified as none/mild (0% to 33%), moderate (34% to 66%), or severe (67% to 100%).
Efficacy and Safety
The primary efficacy end point was moderate or severe vasospasm within 14 days of SAH based on central assessment. The main secondary end point was morbidity and mortality (M/M) within 6 weeks of SAH assessed by local investigators. M/M was defined as at least one of the following: death within 6 weeks of SAH from any cause; new cerebral infarct within 6 weeks of SAH compared with postprocedure CT scan; delayed ischemic neurological deficit (DIND) due to vasospasm within 14 days of SAH; and rescue therapy for DSA or transcranial Doppler vasospasm within 14 days of SAH.
DIND was defined as locally defined vasospasm on DSA or transcranial Doppler associated with neurological worsening lasting for at least 2 hours. Neurological worsening was defined as a decline of at least 2 points in the modified Glasgow Coma Scale or an increase of at least 2 points in the abbreviated National Institutes of Health Stroke Scale.20–22 When patients were not evaluable neurologically, DIND was defined as clinical signs of vasospasm (eg, unexplained fever, new neurological deficit) with vasospasm on DSA or transcranial Doppler or when a new hypodensity was observed on a postprocedure CT scan. Transcranial Doppler criteria for vasospasm were a Lindegaard ratio
3, a mean middle or anterior cerebral artery flow velocity >200 cm/s, or an increase >50 cm/s/24 hours.23 Other causes of neurological worsening had to be excluded.
Rescue therapy was defined as the start of either hemodynamic therapy or angioplasty within 14 days of SAH in the presence of vasospasm on DSA or transcranial Doppler. Clinical outcome was measured by the extended version of Glasgow Outcome Scale assessed by a centrally administered telephone interview at 12 weeks.24
The protocol-defined assessment of M/M included all new infarcts and hypodensities, including those unrelated to vasospasm. We subsequently modified this end point by performing a central, blinded review of the cause of infarcts in patients who had any postbaseline CT scan. A centrally assessed M/M end point was defined as: death from any cause within 6 weeks of SAH; new cerebral infarct due to vasospasm within 6 weeks of SAH; DIND due to vasospasm on centrally reviewed DSA; and any rescue therapy within 14 days of SAH.
Adverse events of specific interest were hypotension, pulmonary complications, anemia, and death occurring at any time within 24 hours of study treatment discontinuation.
Statistics
Sample size was estimated from the Phase 2a study.13 The expected frequency of moderate and severe angiographic vasospasm in the placebo group was 60%. Seventy-nine evaluable patients per group were required to detect a relative risk reduction of 50% reduction in the primary end point using a 2-sided Type 1 error of 0.0166 for each dose comparison against placebo.
The all-randomized data set included all patients randomized and the all-treated set included all randomized patients who received at least one dose of treatment. The safety set was all randomized patients who received at least one dose of study treatment and for whom any safety assessment was reported. The per-protocol set comprised all randomized patients excluding major protocol violators. Major protocol violations were defined as no study drug administration (n=4); study treatment discontinuation or interruption for >12 hours during the 2 days before angiographic moderate or severe vasospasm (n=9); treatment from another treatment group received before angiographic moderate or severe vasospasm or before day 9±2 DSA (n=4); no baseline or day 9±2 DSA (n=37); World Federation of Neurological Surgeons Grade 5 (n=1); no ruptured aneurysm or no or local thin clot on admission CT scan based on central reading; or SAH due to a cause other than aneurysm rupture (n=7).
The primary end point was analyzed using the per-protocol set (primary analysis) and the all-treated set. Secondary and exploratory end points were analyzed using the all-treated set. For patients in whom the end point could not be determined due to missing data or loss to follow-up, occurrence of the end point has been assumed unless the patient completed the treatment period and had no signs of neurological worsening or reported symptomatic vasospasm. Safety analysis was on the all-treated set and summarized by frequencies and percents. Treatment groups were compared using Fisher exact test for the primary and secondary end points. Inferential methods were aimed at demonstrating the superiority of individual clazosentan dose groups over placebo using a studywide 2-sided significance level of 5%. The Bonferroni-Holm rule was applied to adjust for multiple testing. The exact 95% (2-sided) CIs were calculated for proportions. For the relative risk ratios, 95% (2-sided) CIs using normal approximation were calculated. Safety analyses were based on the all-treated set and summarized by frequencies and percents. All analyses were performed using SAS 8.2 software.
| Results |
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There were no significant differences between groups in demographics (Table 1). Eighty-three percent to 94% of patients were white (overall, 365 of 409 [89%]) and the majority were World Federation of Neurosurgical Societies Grades 1 or 2. There was a trend for more patients with thick and diffuse clots in the 3 clazosentan groups. Study treatment was completed by 85 (89%), 83 (77%), 85 (77%), and 77 (79%) patients in the all-randomized set, respectively (Figure 1). Reasons for discontinuation from the study were death (4%, 5%, 8%, and 7%), administrative or other reason (5%, 3%, 3%, and 5%), adverse event (1%, 0%, 1%, and 0%), and lost to follow-up (1%, 0%, 0%, and 1%) in the placebo and 1, 5, and 15 mg/h clazosentan groups, respectively.
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Efficacy
Moderate or severe angiographic vasospasm in the per-protocol set assessed by central reading occurred in 56 patients (66%; 95% CI, 55% to 76%) in the placebo group compared with 41 (43%; 95% CI, 33% to 54%), 37 (39%; 95% CI, 29% to 50%), and 18 (23%; 95% CI, 14% to 34%) patients in the 1, 5, and 15 mg/h clazosentan groups, respectively (P<0.02 for each group compared with placebo; Figure 2). Compared with placebo, the relative risk reductions were 34% (95% CI, 14% to 50%; P=0.0027), 41% (95% CI, 21% to 56%; P=0.0003), and 65% (95% CI, 47% to 78%; P<0.0001) in the 1, 5, and 15 mg/h groups clazosentan, respectively. In the all-treated set, all doses of clazosentan also were associated with significant reductions compared with placebo in moderate or severe vasospasm (P<0.02 for each group compared with placebo). In the placebo group, 64 patients (67%; 95% CI, 56% to 76%) had moderate or severe vasospasm compared with 51 (48%; 95% CI, 38% to 58%), 45 (41%; 95% CI, 32% to 51%), and 30 (31%; 95% CI, 22% to 42%) patients in the 1, 5, and 15 mg/h clazosentan groups, respectively.
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There was no significant difference in the proportion of patients in the all-treated set who developed M/M assessed by the local investigator (30 [31%] in the placebo and 40 [37%], 34 [31%], and 36 [38%] in the 1, 5, and 15 mg/h clazosentan groups, respectively; P>0.1 for all comparisons; Figure 3). A trend toward decreased M/M was observed using the centrally assessed end point (37%, 28%, and 29% with 1, 5, and 15 mg/h, respectively) versus placebo (39%; P>0.1 for all comparisons). Discrepancies between investigator and central assessment of M/M were due mainly to differences in vasospasm-related cerebral infarction and DIND. In patients with available CT scans, the incidence of vasospasm-related new cerebral infarcts was 19% in the placebo group compared with 13%, 9%, and 5% in the 1, 5, and 15 mg/h groups, respectively. DIND showed a similar treatment effect trend (24%, 19%, 17%, and 12% in the placebo, 1, 5, and 15 mg/h groups, respectively). Rescue therapy showed no relation to treatment, being used in 24%, 27%, 17%, and 19% for the same groups. There was no effect of clazosentan on GOSE (Table 2).
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The protocol specified stratification by site and mode of aneurysm treatment (clipping or coiling). There was some interaction between mode of treatment and moderate to severe angiographic vasospasm when tested on the all-treated set (P<0.05,
2 test), which requires detailed description because patients were not randomized to treatment modality and those who underwent clipping differed from those treated by coiling and word limitations preclude description of the analysis here.
Safety
Hypotension, anemia, and pulmonary complications were more frequent in the clazosentan groups (Table 3). Most pulmonary complications occurred during the first 7 days of study drug infusion and included pneumonia, pleural effusion, pulmonary edema, and acute respiratory distress syndrome. Three patients (1%) discontinued the study drug due to hypotension; all were treated with clazosentan.
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There were 25 deaths within 12 weeks postaneurysm rupture in the randomized set, 24 of which occurred in the all-treated set. One death occurred in the 1 mg/h clazosentan group after randomization but before the start of treatment. Mortality was 4 (4%) placebo patients and 4 (4%), 9 (8%), and 7 (7%) patients in the 1, 5 and 15 mg/h clazosentan groups, respectively. Causes of death included cerebral infarction, pulmonary embolism, cardiac arrest, SAH, brain edema, sepsis, and rebleeding. Fourteen of 21 deaths were due primarily to intraoperative complications with a preponderance in the clazosentan groups.
| Discussion |
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Most clinical trials of treatments to prevent vasospasm after SAH used symptomatic as opposed to angiographically documented vasospasm as an end point.5 Nimodipine is the only proven treatment. Meta-analysis of the randomized trials showed that it improved outcome, reduced symptomatic vasospasm, and probably reduced cerebral infarction after SAH.26 In the subgroups of patients in the nimodipine studies who had catheter angiography, however, it did not reduce angiographic vasospasm.27 This in part led to controversy about whether nimodipine was beneficial or whether trial design problems led to the observed benefits. Use of angiographic vasospasm as the primary end point in this study removes this concern and provides strong evidence of the role of endothelin in the pathogenesis of vasospasm.6–12
Despite the marked beneficial effect on angiographic vasospasm, no difference between groups was observed for the vasospasm-related M/M end point when based on investigator assessment. We investigated this further by central blinded review of the components of the M/M end point and found a trend toward decreased incidence of M/M using this modified end point. This was due primarily to a decrease in infarcts related to vasospasm in patients treated with clazosentan. Investigator assessment included more hypodense areas from periprocedural and other causes. Also, there was a decrease in patients who had DIND in the presence of angiographic vasospasm based on central review apparently because investigators sometimes attributed DIND to vasospasm that was measured as only mild by central review. In support of the central review opinion, the incidence of new infarcts related to vasospasm in the placebo group was similar to that reported in the literature.25 These findings support the notion that decreasing vasospasm will improve clinical outcome. They emphasize the need to assess the etiology of CT-based hypodensities in a consistent manner to avoid confounders unrelated to vasospasm and is in agreement with the assessments made in some but not all previous SAH trials.13,28,29
Clazosentan treatment had no obvious effect on functional outcome measured by the GOSE. This study, however, was not powered to detect a treatment effect on clinical outcome. Sample size calculations suggest that thousands of patients need to be randomized to detect a change in the Glasgow Outcome Scale even if vasospasm is completely prevented by treatment.30 This may because the Glasgow Outcome Scale categories focus on physical changes and are not very sensitive to subtle neurological changes such as those occurring after SAH.24,31 From a practical perspective, until more sensitive outcome scales are developed and validated, alternative outcome measures focused on vasospasm-related outcomes may reduce sample size requirements.
Pulmonary complications, hypotension, and anemia were more common at all doses of clazosentan than with placebo. Pulmonary adverse events may have been related to fluid retention, which is postulated to be a class effect of endothelin receptor antagonists.32,33 Anemia may also be dilutional secondary to fluid retention. Overall, the adverse events were generally manageable and not considered serious. The causes of death were not unexpected in this patient population and for the most part could be attributed either to patients underlying condition or major intraoperative complications, which tended to be higher in the clazosentan-treated groups.
Conclusions
This study shows that 1, 5, and 15 mg/h intravenous clazosentan significantly reduces moderate and severe angiographic vasospasm when compared with placebo. The results of the centrally assessed M/M end point showed a trend toward reduction in clinically relevant vasospasm-related events. They also suggest that evaluations of the effects of treatments for vasospasm should avoid confounders such as hypodensities on CT unrelated to vasospasm. Clazosentan increased the incidence of pulmonary complications, anemia, and hypotension. Overall the results support conduct of a Phase 3 clinical trial (CONSCIOUS-2) to evaluate effects of clazosentan on vasospasm-related M/M using central clinical and radiological assessment and with attention to avoidance of excess fluid administration and hypotension.
| Appendix |
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| Acknowledgments |
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Source of Funding
This study was supported by Actelion Pharmaceuticals.
Disclosures
R.L.M., N.F.K., S.M., D.R., P.S., S.W., and A.P. are consultants for Actelion Pharmaceuticals.
Received March 12, 2008; accepted March 26, 2008.
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