Abstract 192: Stroke in the WARCEF Trial

Background The Warfarin vs. Aspirin in Reduced Cardiac Ejection Fraction (WARCEF) trial found no difference between warfarin and aspirin in heart failure patients in sinus rhythm for the outcome of first to occur of 84 ischemic strokes (IS), 7 intracerebral hemorrhages or 531 deaths. Pre-specified secondary analysis showed a 48% HR reduction (p=0.005) in IS risk for warfarin vs. aspirin. We examined this IS benefit for warfarin in post-hoc analyses.

Methods We used the Wilcoxon rank sum test, stratified by prior IS or TIA, to compare the distributions of mRS among warfarin and aspirin IS patients in WARCEF. Median (md) scores and interquartile ranges (IQR) are shown for warfarin and aspirin arms, respectively. We used Fisher’s exact test to compare the effect of warfarin vs. aspirin on fatal IS; a stratified exact test to compare proportions of severe (mRS 3-5) IS; and stratified Poisson regression to compare IS subtypes.

Results Twenty-nine (2.5%) of 1142 patients on warfarin and 55 (4.7%) of 1163 on aspirin had IS. The warfarin IS rate (0.72 per 100 patient years [/100PY]) was lower than for aspirin (1.36/100PY). There were no differences between warfarin and aspirin IS patients in baseline mRS (md 1, IQR, 2, N=29 vs. md 1, IQR 2, N=55); fatal IS (3/29, 10.3% vs. 6/55, 10.9%, p=1.0), or post-IS (after 90+30 days) mRS (md 2, IQR 3, n=23 vs. md 2, IQR 3, n=48, p=0.437). There were also no differences between warfarin and aspirin in change from baseline to post-IS mRS (md 1, IQR 3, n=23 vs. md 1, IQR 3, n=48, p=0.884). Cardioembolic IS was significantly less frequent on warfarin than on aspirin (9 [0.22/100PY] vs. 22 [0.55/100PY], p=0.012). The warfarin arm showed trends to fewer severe (mRS 3-5) IS (3/23 [13.0%] vs. 16/48 [33.3%], p=0.086) and a lower rate of IS of potential cardioembolic etiology (15 [0.37/100PY] vs. 27 [0.67/100PY] p=0.063). There was no difference between warfarin and aspirin in rate of non-cardioembolic IS (5 [0.12/100PY] vs. 6 [0.15/100PY], p=0.768).

Conclusions Warfarin appears superior to aspirin in reducing the frequency of cardioembolic IS in heart failure patients in sinus rhythm. This is supported by trends to lower frequencies of severe IS and potentially cardioembolic IS in patients on warfarin compared to aspirin.

Patent foramen ovale, cardiac valve thickening, and antiphospholipid antibodies as risk factors for subsequent vascular events: the PICSS-APASS study

BACKGROUND AND PURPOSE

We sought to estimate risk of recurrent stroke/TIA/death in the subgroup of the Patent Foramen Ovale in the Cryptogenic Stroke Study (PICSS) cohort with patent foramen ovale (PFO) and antiphospholipid antibodies (aPL) and to estimate risk of recurrent stroke/TIA/death in aPL-positive patients who have thickened left-side heart valves (VaT). PFO is associated with cryptogenic ischemic stroke. Also, the presence of aPL is associated with ischemic cerebrovascular disease.

METHODS

Combined data from 2 major substudies of the Warfarin Aspirin Recurrent Stroke Trial (WARSS) were evaluated. PICSS subjects were included if they were enrolled in the Antiphospholipid Antibodies and Stroke Study (APASS) and underwent a baseline aPL test (lupus anticoagulant, anticardiolipin antibodies, or both) within 1 month of the stroke. All patients in PICSS underwent transesophageal echocardiography for PFO as well as VaT, which was performed blinded to aPL status and treatment arm (325 mg/day aspirin or adjusted dose warfarin; target international normalized ratio, 1.4-2.8). The primary outcome event was the 2-year risk of recurrent stroke/TIA/death and was evaluated using Cox proportional hazards model. Because there was no treatment effect, warfarin and aspirin groups were combined to increase power. For the combined end point, power to detect HR of 2 was 47.8% for the PFO and aPL-positive group, and 75.3% for the valve thickening and aPL-positive group, assuming 2-sided type I error of 0.05.

RESULTS

Five hundred twenty-five subjects were tested for the combined presence of PFO and aPL and were available for evaluation. The primary outcome event rate was 23.9% (HR, 1.39; 95% CI, 0.75-2.59) in the PFO-positive/aPL-positive group, compared to 13.9% (HR, 0.83; 95% CI, 0.44-1.56) in the PFO-positive/aPL-negative group, and 19.9% (HR, 1.16; 95% CI, 0.68-1.90) in the PFO-negative/aPL-positive group. Five hundred forty-five subjects tested for combined presence of aPL and left-side cardiac VaT were available for evaluation. The primary event rate was 22.6% (HR, 1.65; 95% CI, 0.88-3.09) in the VaT-positive/aPL-positive group, compared to 19.4% (HR, 1.50; 95% CI, 0.82-2.75) in the VaT-positive/aPL-negative group, and 20.2% (HR, 1.63; 95% CI, 0.81-3.25) in the VaT-negative/aPL-positive group.

CONCLUSIONS

The combined presence of aPL either with a PFO or with left-side cardiac VaT did not significantly increase risk of subsequent cerebrovascular events in this PICCS/APASS cohort of patients.

Comparison of warfarin versus aspirin for the prevention of recurrent stroke or death: subgroup analyses from the Warfarin-Aspirin Recurrent Stroke Study

BACKGROUND AND PURPOSE

We performed a combination of prespecified and exploratory subgroup analyses to detect any treatment differences among various baseline subgroups in the Warfarin-Aspirin Recurrent Stroke Study (WARSS) cohort.

METHODS

The WARSS compared the efficacy of adjusted-dose warfarin (INR 1.4-2.8) to aspirin (325 mg/day) for recurrent ischemic stroke or death within 2 years. The effect of warfarin and aspirin was compared among prespecified and exploratory subgroups with respect to sociodemographic and vascular risk factors, stroke subtype, arterial territory, and infarct topography. Hazard ratios and 95% confidence intervals comparing warfarin to aspirin were calculated using Cox proportional hazards models. Differences in hazard ratios were tested using interaction terms.

RESULTS

No treatment differences between warfarin and aspirin were found across multiple prespecified subgroups. In a multivariate model, warfarin was associated with greater hazard among patients with moderate stroke severity (HR 1.63, 95% CI 1.005-2.64, p = 0.047) and a greater benefit among those with posterior circulation location without brainstem infarction (HR 0.54, 95% CI 0.33-0.88, p = 0.013). In post-hoc analyses of the cryptogenic subgroup, warfarin was associated with worse outcomes among patients with moderate stroke severity and better outcomes among those without baseline hypertension or with posterior circulation infarcts sparing the brainstem.

CONCLUSIONS

In the WARSS, the majority of subgroup analyses showed no benefit of warfarin over aspirin. Warfarin benefit was limited to brainstem-sparing posterior circulation infarcts and select cryptogenic stroke subgroups. Pending future clinical trial evidence to the contrary, antiplatelets are recommended for survivors of noncardioembolic stroke.

A two-stage design for a phase II clinical trial of coenzyme Q10 in ALS

BACKGROUND

The combination of a small pool of patients at any given time with the availability of many potential neuroprotective agents to be tested in ALS requires efficient phase II trial designs.

OBJECTIVE

To describe the design of the Clinical Trial of High Dose Coenzyme Q10 (CoQ10) in ALS (QALS study)--a phase II, randomized, placebo-controlled, double-blind, multicenter clinical trial.

METHODS

The study design features two stages. The first stage (dose selection) identifies which of two doses of CoQ10 (1800 mg or 2700 mg) is preferred using a selection procedure rather than a formal hypothesis test. The second stage (early efficacy test) compares the preferred dose of CoQ10 against placebo using a non-superiority or futility design. Data from patients assigned to the preferred dose of CoQ10 in the first stage are also used in the second stage. The primary outcome measure is the decline in Amyotrophic Lateral Sclerosis Functional Rating Scale-revised (ALSFRSr) score from baseline to 9 months.

RESULTS

The total sample size required is 185 patients, as compared to a much larger sample size estimated to be necessary using a conventional superiority design (total: 852 patients). The authors report a bias correction made necessary by the inclusion of patient data from the first stage in the second stage.

CONCLUSIONS

Several features of the Clinical Trial of High Dose Coenzyme Q10 in ALS study design promote efficiency. These features may be beneficial in phase II trials in amyotrophic lateral sclerosis and other fields.

The ALSFRSr predicts survival time in an ALS clinic population

OBJECTIVE

To determine whether the Amyotrophic Lateral Sclerosis Functional Rating Scale-revised (ALSFRSr), a predictor of survival time in ALS clinical trials, predicts survival time in an ALS clinic population.

METHODS

The authors prospectively evaluated 267 consecutive patients with ALS at first visit to an ALS clinic using the ALSFRSr and pulmonary function testing. The association of ALSFRSr score at baseline with death or tracheostomy in ALS was examined using Cox proportional hazards models, adjusting for age at baseline, sex, and symptom duration.

RESULTS

Of 267 patients with ALS, 103 (39%) reached the endpoint, defined as either death (79 patients) or tracheostomy (24 patients), during a mean follow-up of 1.0 +/- 0.7 years. Among the 103 patients who reached the endpoint during follow-up, 77 (75%) had a baseline ALSFRSr score of less than 38 (the median baseline score of all patients), compared to 53 of 164 (32%) who remained alive without tracheostomy. Patients with a total ALSFRSr score below the median had a 4.4-fold increased risk of death or tracheostomy compared to those who scored above the median (HR: 4.38, 95% CI: 2.79 to 6.86, p < 0.001). Both the total ALSFRSr score at baseline (HR: 0.94, 95% CI: 0.91 to 0.98, p < 0.001) and forced vital capacity at baseline (HR: 0.99, 95% CI: 0.98 to 1.00, p = 0.02) were associated with death or tracheostomy when included in the same Cox model.

CONCLUSIONS

In an ALS clinic population, the total Amyotrophic Lateral Sclerosis Functional Rating Scale-revised score at baseline is a strong predictor of death or tracheostomy independently of forced vital capacity and after adjustment for age at baseline, sex, and symptom duration.

Antiphospholipid antibodies and subsequent thrombo-occlusive events in patients with ischemic stroke

CONTEXT

The presence of antiphospholipid antibodies (aPL) has been associated with vascular occlusive events. However, the role of aPL in predicting ischemic events, particularly recurrent ischemic stroke, is controversial.

OBJECTIVE

To evaluate the effect of baseline aPL positivity (ie, positivity for anticardiolipin antibodies [aCL], lupus anticoagulant antibodies [LA], or both) on subsequent thrombo-occlusive events, including recurrent stroke.

DESIGN, SETTING, AND PARTICIPANTS

The Antiphospholipid Antibodies and Stroke Study (APASS), a prospective cohort study within the Warfarin vs Aspirin Recurrent Stroke Study (WARSS), a randomized double-blind trial (N = 2206) conducted at multiple US clinical sites from June 1993 through June 2000 and comparing adjusted-dose warfarin (target international normalized ratio, 1.4-2.8) and aspirin (325 mg/d) for prevention of recurrent stroke or death. APASS participants were 1770 (80%) WARSS participants who consented to enroll in the APASS, with usable baseline blood samples drawn prior to randomization to the WARSS and analyzed for aPL status within 90 days of index stroke by a central independent laboratory. Quality assurance was performed on approximately 10% of samples by a second independent laboratory.

MAIN OUTCOME MEASURE

Two-year rate of the composite end point of death from any cause, ischemic stroke, transient ischemic attack, myocardial infarction, deep vein thrombosis, pulmonary embolism, and other systemic thrombo-occlusive events. The primary analysis assessed the outcome associated with aPL positivity within each WARSS treatment group separately, after risk-factor adjustment (since these aPL-positive vs aPL-negative comparisons were not randomized).

RESULTS

Of the 1770 APASS patients, 720 (41%) were classified as aPL-positive and 1050 (59%) as aPL-negative. There was no increased risk of thrombo-occlusive events associated with baseline aPL status in patients treated with either warfarin (relative risk [RR], 0.99; 95% confidence interval [CI], 0.75-1.31; P =.94), or aspirin (RR, 0.94; 95% CI, 0.70-1.28; P =.71). The overall event rate was 22.2% among aPL-positive and 21.8% among aPL-negative patients. There was no treatment x aPL interaction (P =.91). Patients with baseline positivity for both LA and aCL antibodies tended to have a higher event rate (31.7%) than did patients who tested negative for both antibodies (24.0%) (unadjusted RR, 1.36; 95% CI, 0.97-1.92; P =.07). Classification and regression tree analyses did not identify a specific LA test or aCL isotype or titer that was associated with increased risk of thrombo-occlusive event.

CONCLUSIONS

The presence of aPL (either LA or aCL) among patients with ischemic stroke does not predict either increased risk for subsequent vascular occlusive events over 2 years or a differential response to aspirin or warfarin therapy. Routine screening for aPL in patients with ischemic stroke does not appear warranted.