All Aboard the tPA Hype Bus

Indiscriminate use of tPA in those with undifferentiated stroke is a low-value proposition – even if you find the evidence reliable. The utility of tPA for stroke depends on anatomy, time, and tissue status – information the traditional non-contrast head CT does not usually provide. Unfortunately, one of the latest “innovations” in stroke care is simply to do this useless test faster – in a bus, down by the river.

This is the PHAST project out of Cleveland, which, like similar efforts in Berlin, Chattanooga, and Houston, puts a CT scan machine in an oversized ambulance. Many of the initial phases of these projects included a stroke physician physically in the vehicle – but this, as you would expect, takes advantage of telemedicine technology to provide consultation from afar.

The stated hypothesis of this project is “that the MSTU will allow significant reductions in time to evaluation and treatment of patients when compared to a traditional ambulance model in an American urban environment”, which is just mind-numbingly infantile. Of course, pre-hospital administration will be faster than in-house thrombolysis – the interesting data would be with regard to safety and misdiagnosis.

This report is of the first 100 patients evaluated – generated by 317 system alerts. Of these, 33 were given a preliminary diagnosis of probable stroke, 30 possible stroke, 4 transient ischemic attacks, 5 intracerebral hemorrhages, and 28 non-cerebrovascular. Of the 33 probable strokes, 16 received thrombolysis – and, by most of their various metrics, care was accelerated by 20-40 minutes. And, then, no outcomes, safety, or follow-up data is presented – apparently we are simply supposed to operate under the assumption this resource outlay and rush to provide the substrate for potential tPA administration is obviously prudent and effective care.

Probably the only interesting tidbit from this paper was with regard to one of the cases of ICH diagnosed by CT in the prehospital setting. One patient was identified as taking anticoagulation, and prothrombin concentrate complexes were initiated in the pre-hospital setting. The timeliness of anticoagulation reversal is almost certainly beneficial, although the magnitude of effect for the few minutes saved is uncertain.

“Reduction in time to treatment in prehospital telemedicine evaluation and thrombolysis”

http://www.neurology.org/content/early/2017/03/08/WNL.0000000000003786.abstract

Thrombolysis and the Aging Brain

The bleeding complications of thrombolysis are well-described, but frequently under-appreciated in the acute setting. Stroke patients often disappear upstairs after treatment in the Emergency Department quickly enough that we rarely see the neurologic worsening associated with post-thrombolysis hemorrhage.

Risk factors for post-tPA ICH are well-known, but often difficult to precisely pin down for an individual patient. This study pools patients from up to 15 studies to evaluate the effect of leukoariosis on post-tPA hemorrhage. Leukoariosis, essentially, is a cerebral small vessel disease likely related to chronic ischemic damage. It has been long-recognized as a risk factor for increased hemorrhage and poor outcome, independent of age at treatment.

In this study, authors pooled approximately 5,500 patients, half of which were identified to have leukoariosis. The unadjusted absolute risk of symptomatic ICH in those without leukoariosis was 4.1%, while the risk of those with was 6.6%. Then, looking at the 2,700 patients with leukoariosis, those with mild disease had an unadjusted absolute risk of 4.0%, compared with 10.2% for those with moderate or severe. Similar trends towards worse functional outcomes were also seen with regards to worsening leukoariosis.

The moral of the story: the baseline health of the brain matters. When discussing the risks, benefits, and alternatives for informed consent with a family, these substantial risks in those patients with leukoariosis should be clearly conveyed with regards to appropriateness of tPA when otherwise potentially indicated.

“Leukoaraiosis, intracerebral hemorrhage, and functional outcome after acute stroke thrombolysis”

http://www.neurology.org/content/early/2017/01/27/WNL.0000000000003605.abstract

Some Old News About Thrombolysis Before Endovascular Therapy

We’ve spent a little bit of energy on this blog teasing out the appropriate indications for endovascular therapy, and and we’ve used a few of those words to discuss whether thrombolysis prior to is necessary. I am of the opinion: probably not.

It turns out, there are many other prominent neurologists who share that same opinion. Unfortunately, this article is just a rehash of prior data without any new specific insight. Of course, the lay medical press does their typical job of creating definitive, misleading headlines:
Stroke: No Benefit from Adding tPA to Thrombectomy
No Benefit for IV tPA Before Mechanical Thrombectomy in Ischemic Stroke

This is a small post-hoc analysis of the 291 patients undergoing treatment in the SWIFT and STAR trials. Of these, 131 did not receive thrombolysis prior to intervention, with the most common exclusion being either presence of an elevated INR and oral anticoagulation or symptom onset being >4 hours prior to hospital arrival. Other, less common exclusions included blood pressure exclusions, hypoglycemia, and prior strokes. Some patients also received bridging tPA or reduced-dose tPA, as determined appropriate by the interventionalist.

In such a small analysis such as this, little reliable can be made of the results – except to generally say there was no obvious signal confirming nor refuting the appropriateness of thrombolysis prior to intervention. Hemorrhagic complications were similar between groups, as were patient-oriented outcomes. At the least, they offer the appropriate weak conclusion supported by these data: prospective trials are reasonable.

“Combined Intravenous Thrombolysis and Thrombectomy vs Thrombectomy Alone for Acute Ischemic Stroke: A Pooled Analysis of the SWIFT and STAR Studies”
http://jamanetwork.com/journals/jamaneurology/article-abstract/2596239

tPA For Wake-Up Strokes – “Safe!”

It’s medical news nonsense time again – this time featuring our old favorite, tPA for stroke.

“Tissue Plasminogen Activators Safe for Patients Who Wake Up with Stroke Symptoms” reports HCP Live, and featured in the ACEP daily e-mail newsletter. Oddly enough, this article was actually initially published back in July before being picked up by the health news blog world here in December.

As the headline suggests, this is an article regarding “wake-up” strokes, those with an unknown time of onset because the patient was last seen normal prior to sleep. The authors hypothesize this might represent an otherwise missed, but eligible, population if their stroke onset was close to waking.

But, in this open-label study spanning 3 years of enrollment, there is absolutely nothing conclusive to be said. During this period, across five centers, these authors managed to enroll only 40 patients – the vast majority of whom had NIHSS less than 10, and four of whom were mimics. Following treatment, six suffered intracerebral hemorrhage, two developed angioedema, and one suffered systemic hemorrhage – and thus, the apparent conclusion, that tPA is “safe” in this population.

In reality, this hardly tells us anything of the sort – generalizing results from this cohort of mostly small strokes to a larger treatment population is obviously inappropriate.  But, the authors state it forms the foundation of future trials – and, no doubt, they are underway already.

“Prospective, Open-Label Safety Study of Intravenous Recombinant Tissue Plasminogen Activator in Wake-Up Stroke”

https://www.ncbi.nlm.nih.gov/pubmed/27273860

Endovascular Therapy for Large Ischemic Cores

The vast majority of the important evidence regarding the use of endovascular therapy for stroke has substantial limitations. The critical studies, with the largest magnitude of benefit, used strict imaging criteria to limit interventions to large-vessel occlusions with only small-volume ischemic cores surrounded by large regions of surviving tissue. Further generalizing these data to the remaining stroke population represents a significant challenge.

This small study tries to describe the benefit of endovascular treatment in a population with larger ischemic core volumes, specifically those greater than 50 mL – and it’s useless. They have 56 patients in their retrospective case-control comparison, and are missing long-term follow-up data for 9. Outcomes, yes, are better for the endovascular therapy group – a handful of patients had low or minimal disability, while none of the control patients achieved an mRS 0-2. Safety outcomes, of course, are a total wash in a small sample such as this. This would have made for a great conference abstract, but it is hardly compelling or significant data.

The main notable feature of this study is mostly how it reflects the real-world deployment of this therapy, regardless of the guidelines and current evidence.  Many centers have expanded the use of endovascular intervention for patients beyond the scope of the original trials.  These are very, very weak data – and, even though I don’t disagree in principle with imaging-guided revascularization, the further away from established evidence we drift, the lower value the intervention becomes.

“Endovascular Treatment for Patients With Acute Stroke Who Have a Large Ischemic Core and Large Mismatch Imaging Profile”
https://www.ncbi.nlm.nih.gov/pubmed/27820620

Which is Safer – Rivaroxaban or Dabigatran (or Neither?)

The world of anticoagulation turned upside-down with dabigatran, and continued with the Factor Xa inhibitors: rivaroxaban, apixaban, and edoxaban. While RE-LY and its ilk showed, in the settings of controlled clinical trials, that these new agents were potentially superior, or at least non-inferior, to warfarin – which is best? Do we have any idea?

Unfortunately, such comparative effectiveness work is sadly lacking, and we are forced to try and glean safety data indirectly following approval. This study pools Medicare beneficiaries using the new agents for stroke prevention in the setting of nonvalvular atrial fibrillation, and attempts to observe “real world” outcomes.

The winner on stroke prevention: rivaroxaban, by a hair. The winner on bleeding: dabigatran, by a long shot, both intra-cranial and extra-cranial. Overall mortality, then, slightly favored dabigatran.

These data are retrospective and tortured by statistical matching methods, so their reliability is hardly bulletproof. What this does raise are more questions about the appropriate usage of these new agents – and further emphasizes the importance of prospectively performed patient-centered effectiveness research.

“Stroke, Bleeding, and Mortality Risks in Elderly Medicare Beneficiaries Treated With Dabigatran or Rivaroxaban for Nonvalvular Atrial Fibrillation”

http://archinte.jamanetwork.com/article.aspx?articleid=2560376

Stretch That Thrombectomy Window

It’s the thing to do in stroke – wedge new treatments into practice with a narrow time window and strict eligibility requirements, then expand, expand, expand.

This latest publication/advertising supplement in the Journal of the American Medical Association pools together the endovascular trials MR CLEAN, ESCAPE, EXTEND-IA, REVASCAT, and SWIFT-PRIME for an individual-patient meta-analysis to explore the various nuances of the treatment effect. After much cleaning and tweaking, the authors come around and say “Whoa! We found a benefit out to 7.3 hours from symptom onset, not just the 6 hour limit recommended by the American Heart Association!”

These were all positive trials, so it’s no surprise the overall outcome is positive – nor is these authors ability to drag out favorable outcomes beyond the 6-hour cut-off, considering some of these trials enrolled patients out to twelve hours. However, in their clumsy calisthenics to marry these data to the time-based hypothesis of acute stroke practice, these authors are clearly dancing around the most important bit of evidence emerging from these trials: imaging selection. They spend a handful of sentences discussing the imaging selection eligibility criteria of the included trials, but one benefit of meta-analyses is its use as a tool to obfuscate such inconvenient aspects in favor of words, words, words relating to the methods of their statistical analysis.

As I described in my #smaccDUB talk, you need two things for stroke therapy to be effective: viable tissue and effective reperfusion. These trials – ESCAPE, EXTEND-IA, and SWIFT-PRIME – finally hit that sweet spot with small infarct cores and safe, effective recanalization. Some of that viable tissue absolutely decays over time, so the time-based hypothesis is not entirely untrue, but it’s a low-value oversimplification. As many of use in Comprehensive Stroke Centers have seen, perfusion imaging can direct therapy for patients far outside the general AHA recommendations. The obvious corollary to this, however, is that perfusion imaging similarly identifies patients for whom intervention is futile, regardless of time window. This second point runs contrary, however, to the financial interests at stake here.

The authors do mention imaging-based criteria is being investigated in multiple clinical trials, e.g.: NCT02142283, NCT02586415.  However, these trials are carefully designed not to enroach upon established time-based criteria, and to use imaging only to further extend the treatment windows.

Other fun tidbits:

  • A few patients randomized to endovascular intervention did not receive one. After all, most received pre-intervention tPA – some would be expected to recanalize with medical therapy alone. However, this publication gives another lovely window into our clot-buster that doesn’t bust clots: only 6.8% could be reasonably concluded to have had clot thrombolysis after medical therapy alone. We probably should not be giving tPA to patients for whom endovascular intervention is planned.
  • All five studies cited here were published in the New England Journal of Medicine.  This meta-analysis is in JAMA. Presented without comment.

“Time to Treatment With Endovascular Thrombectomy and Outcomes From Ischemic Stroke: A Meta-analysis”

http://jama.jamanetwork.com/article.aspx?articleid=2556124

 

Coda – there were just a couple relevant conflict of interest disclosures:

Dr Saver reports being an employee of the University of California; serving as an unpaid site investigator in multicenter trials run by Medtronic and Stryker for which the UC Regents received payments on the basis of clinical trial contracts for the number of subjects enrolled; receiving stock options for services as a scientific consultant regarding trial design and conduct to Cognition Medical; receiving funding for services as a scientific consultant regarding trial design and conduct to Covidien/Medtronic, Stryker, Neuravi, BrainsGate, Pfizer, Bristol Myers-Squibb, Boehringer Ingelheim (prevention only), ZZ Biotech, and St Jude Medical; serving as an unpaid consultant to Genentech advising on the design and conduct of the PRISMS trial; neither the University of California nor Dr Saver received any payments for this voluntary service. The University of California has patent rights in retrieval devices for stroke. Dr Goyal reports receiving grants from Covidien/Medtronic, consulting payments from Covidien/Medtronic, and having patent rights in systems and methods for diagnosing strokes (PCT/ CA2013/000761) licensed to GE Healthcare. Dr van der Lugt reports grant funding from the Dutch Heart Foundation, AgioCare BV, Medtronic/Covidien/EV3, MEDAC Gmbh/LAMEPRO/Penumbra, Stryker, and Top Medical/Concentric. Dr Menon reports serving as an unpaid member of in the ESCAPE trial, which received support from Covidien/Medtronic, receiving grant support from AstraZeneca, honoraria from Penumbra, a submitted patent for triaging systems in ischemic stroke, and serving on the board of QuikFlo Health. Dr Majoie reports that his institution has received honoraria for his service on a Speaker’s Bureau from Stryker. Dr Dippel reports that his institution has received honoraria for his speaking from Stryker and grant funding from the Dutch Heart Foundation, AgioCare BV, Medtronic/Covidien/EV3, MEDAC Gmbh/ LAMEPRO, Penumbra, Stryker, and Top Medical/ Concentric. Dr Campbell reports that his institution received a grant to support the EXTEND-IA trial from Covidien/Medtronic. Dr Campbell reports grant funding from the National Health and Medical Research Council of Australia and Medtronic and fellowships from the National Heart Foundation of Australia, National Stroke Foundation of Australia, and Royal Australasian College of Physicians. Dr Nogueira reports receiving fees for service on steering and data safety monitoring committees to Medtronic, Stryker, Penumbra, and Rapid Medical. Dr Demchuk reports receiving grant support and personal fees from Covidien/Medtronic and personal fees from Pulse Therapeutics. Dr Devlin reports that his institutions received clinical trial payments for patients enrolled in clinical trials from Medtronic, clinical trial support from Brainsgate and Genervon, and holding a patent. Dr Frei reports personal fees from Penumbra, Stryker, Codman, MicroVention, and Siemens. Dr Jovin reports receiving fees for service on steering committees from Silk Road Medical, Covidien, Stryker Neurovascular, Air Liquide; personal fees from Neuravi and Johnson & Johnson; nonfinancial support from Fundacio Ictus; and serving on the advisory board for Anaconda. Dr Siddiqui reports personal fees from StimSox, Valor Medical, Neuro Technology Investors, Cardinal Health, Medina Medical Systems, Buffalo Technology Partners, International Medical Distribution Partners, Codman & Shurtleff, Medtronic, GuidePoint Global Consulting, Penumbra, Stryker, MicroVention, W. L. Gore & Associates, Three Rivers Medical, Corindus, Amnis Therapeutics, CereVasc, Pulsar Vascular, the Stroke Project, Cerebrotech Medical Systems, Rapid Medical, Lazarus, Medina Medical, Reverse Medical, Covidien, Neuravi, Silk Road Medical, Rebound Medical, Intersocietal Accreditation Committee; other fees from Penumbra, 3D Separator Trial, Covidien, SWIFT PRIME and SWIFT DIRECT trials, MicroVention, FRED trial, CONFIDENCE study, LARGE trial, POSITIVE trial, COMPASS trial, INVEST trial. Dr van Zwam reports that his institution has received honoraria for his speaking from Stryker and Codman. Dr Davis reports lecture fees and research support from Covidien/Medtronic; travel support from Bristol Myers-Squibb and Pfizer; and advisory board fees from Boehringer Ingelheim and Medtronic. Dr Silver reports personal fees from Boehringer Ingelheim. Dr Donnan reports nonfinancial support from Boehringer Ingelheim; grants from the Australian National Health and Medical Research Council; and fees for service on advisory boards for Boehringer Ingelheim, AstraZeneca, Bristol Myers-Squibb, Pfizer and Merck Sharp & Dohme. Dr Brown reports receiving consulting fees from Medtronic/Covidien and personal fees from the University of Calgary. Dr Mitchell reports that his institution received a grant to support the EXTEND-IA trial from Covidien/Medtronic; his institution has received unrestricted research funding and grants from Codman Johnson and Johnson, Medtronic, and Stryker; and serving as an unpaid consultant to Codman Johnson and Johnson. Dr Davalos reports receiving payments for serving on a multicenter study steering committee and grant funding from Medtronic. Dr Roos reports grant funding from Medtronic. Dr Hill reports unrestricted grant funding for the ESCAPE trial to University of Calgary from Covidien/Medtronic, and active/in-kind support consortium of public/charitable sources (Heart and Stroke Foundation, Alberta Innovates Health Solutions, Alberta Health Services) and the University of Calgary (Hotchkiss Brain Institute, Departments of Clinical Neurosciences and Radiology, and Calgary Stroke Program); personal fees from Merck, nonfinancial support from Hoffmann-La Roche Canada. In addition, Dr Hill has a submitted patent for triaging systems in ischemic stroke, and owns stock in Calgary Scientific, a company that focuses on medical imaging software. No other disclosures were reported.
Funding/Support: The HERMES pooled analysis project is supported by a grant from Medtronic to the University of Calgary.

But Where is the Antidote to the Poison @NEJM?

Andexanet alfa is the long-awaited antidote for the Factor Xa inhibitors – rivaroxaban, apixaban, edoxaban, and their ilk. This publication, featured at the European Stroke Congress and in the New England Journal of Medicine, is Portola’s latest update regarding its utility. Is it better than their previous update – their failure to receive initial FDA approval – or just another “incomplete” like their publication last fall?

This is ANNEXA-4, an open-label, single-group study purporting to evaluate the efficacy and safety of andexanet for clinical hemostasis in actively bleeding patients with concomitant use of Factor Xa inhibitors. Or, more specifically, these are interim results – the first 67 of 250 planned for enrollment. The clinical efficacy endpoint is a complex series of adjudicated judgements regarding the cessation of bleeding, hematoma expansion, or change in hematocrit, depending on the type of bleeding enrolled. The primary safety endpoint is death or thrombotic event within 30 days – stroke, myocardial infarction, venous thromboembolism, etc.

There is virtually nothing positive to relate here. The authors, of course, relate that somewhere around 80% of the 47 patients included in their efficacy analysis obtained “good” or “excellent” hemostasis with 12 hours following their andexanet infusion. But, these essentially arbitrary labels at a potentially clinically unimportant timepoint tells us virtually nothing regarding its value versus observation, or an alternative treatment such as prothrombin concentrate complexes.

On the negative side, the list is endless. There is the baffling offensiveness of publishing what amounts to a quarter of a trial in the New England Journal of Medicine.  The mean time to andexanet bolus was nearly 5 hours, raising concern regarding the acuity and severity of bleeding in enrolled patients.  The vague, patient-oriented endpoints are meaningless – with or without a comparator – and thus, this boils down to basically a pharmacokinetic observational study. Even then, the pharmacokinetics don’t appear terribly favorable – andexanet dramatically reduces Factor Xa activity during infusion, but pops back to therapeutic anticoagulation following cessation. A concerning 18% had thrombotic events within 30 days – but, again, without any control group, little can be concluded regarding safety.

Finally, clearly, the NEJM has given up publishing the conflicts-of-interest for the authors because it would sum up to half the journal – this article directs the reader to the disclosure forms on the web. For the eagle-eyed reader, however, they can pick out this text as part of the author affiliations: “Portola Pharmaceuticals, San Francisco (J.T.C., A.G., M.D.B., G.L., P.B.C., S.G., J.L., B.L.W.)”. Yes, eight of the authors are employees of Portola Therapeutics, the manufacturer. Better even, are their ICJME form disclosures. John Curnutte, the Head of Research and Development, has checked the box stating he has no relevant conflicts of interest with the work under consideration for publication – but, you know, outside the submitted work he happens to be an employee for Portola. In fact, from what I can tell, every employee authoring this article declared they have no COI with the work under consideration for publication.

Inconceivable!

Andexanet Alfa for Acute Major Bleeding Associated with Factor Xa Inhibitors
http://www.nejm.org/doi/full/10.1056/NEJMoa1607887

Shaking Out Stroke Mimics

In a world of continued aggressive guideline- and pharmaceutical-sponsored expansion of stroke treatment with thrombolytics, this article fills and important need – better codifying the predictors of stroke mimics. While other editorials espouse the need to be fast without being sure, this is frankly irresponsible medicine – and, in resource-constrained environments, unsustainable.

These authors at two academic centers performed a retrospective clinical and imaging review of 784 patients evaluated for potential acute cerebral ischemia. Patients were excluded if they had signs of acute stroke on initial non-contrast imaging, and if they did not subsequently undergo MRI. Based on review of the totality of clinical information for each patient, 41% of this cohort were deemed stroke mimics. The authors scoring system, then derived 6 variables – and 3 or more were present, the chance of stroke mimic being cause of the current presentation was 87.2%. Their criteria:

  • Absence of facial droop
  • Age <50 y/o
  • Absence of atrial fibrillation
  • SBP <150 mm Hg
  • Presence of isolated sensory deficit
  • History of seizure disorder

When the rate of tPA administration to stroke mimics is ~15%, and 30-40% of patients evaluated for stroke are stroke mimics – there is a lot of waste and potential harm occurring here. These authors suggest the use of this score could potentially halve these errant administrations for 94% sensitivity, or cut errant administrations down to 2% with 90% sensitivity. Considering the patients for which stroke/stroke mimic is an ambiguous diagnosis, it is reasonably likely the symptoms are of lesser severity – and in the range for which tPA is of most tenuously “proven” value. While their rule has not been prospectively validated, some of these elements certainly have face validity, and can be incorporated into current practice at least as a reminder.

“FABS: An Intuitive Tool for Screening of Stroke Mimics in the Emergency Department”

http://stroke.ahajournals.org/content/early/2016/08/04/STROKEAHA.116.013842.abstract

Don’t Stop at the Headline

The verdict is in: “Aspiration Thrombectomy No Help for Large-Clot Strokes”, reports MedPage Today.

Except, they’re not precisely correct – in a way, you could even say they’re wrong.

This is THERAPY, an endovascular trial in acute stroke featuring the Penumbra aspiration device.  This is somewhat unique, as the technology differs from the otherwise popularized Solitaire retrieval system. This trial is also different from the most contemporary comparators, as its imaging criteria did not rely on perfusion imaging, but, rather, simply large-vessel occlusion with a clot length of 8mm or greater.

The results of the trial, as you might have picked up from the lay press headline, were negative – that is to say, they did not reach statistical significance. Their primary endpoint for modified Rankin Scale of 0-2 was achieved in 38% receiving endovascular treatment and 30% receiving intravenous thrombolysis alone, and this 8% absolute difference produced a p-value of only 0.52. However, the trial was initially scheduled to enroll 692 patients to be powered to detect a 10.6% difference, but stopped enrollment after 108 based on the publication of other positive endovascular trials.

So, simply put, this trial tells us hardly anything. Is the Penumbra system just as good as Solitare? Probably, but perhaps we’ll never know for certain. Does the 8% difference seen in this trial reflect the lower magnitude of effect of treatment relating to lack of perfusion imaging? Probably, as well, based on the the larger evidentiary context.

But, at the minimum, the medical reporting has simply gone off course with their headline.

“Aspiration Thrombectomy After Intravenous Alteplase Versus Intravenous Alteplase Alone”
http://www.ncbi.nlm.nih.gov/pubmed/27486173