Meta-analysis backs thrombectomy over standard stroke care

By Eleanor McDermid, Senior medwireNews Reporter

A meta-analysis published in JAMA confirms that stroke patients can achieve better functional outcomes after mechanical thrombectomy than after intravenous (iv) tissue plasminogen activator (tPA) alone.

They do not, however, have a reduced risk of mortality or symptomatic intracranial haemorrhage, the findings indicate.

The meta-analysis, conducted by Saleh Almenawer (McMaster University, Hamilton, Ontario, Canada) and team, included eight randomised controlled trials involving 2423 patients. Three of the included trials had a neutral result (SYNTHESIS, IMS III, MR RESCUE), while the others were positive in favour of thrombectomy (MR CLEAN, ESCAPE, EXTEND-IA, SWIFT-PRIME, REVASCAT).

In an editorial accompanying the study, Joanna Wardlaw and Martin Dennis, both from the University of Edinburgh in the UK, caution that five of the eight trials were halted early, noting that such trials often produce larger treatment effects than those that accrue their planned sample size.

In the meta-analysis, 44.6% of patients who underwent thrombectomy (mostly preceded by iv tPA) achieved functional independence, defined as a 90-day modified Rankin Scale (mRS) score of 0–2, compared with 31.8% of those given standard care with tPA.

The distribution of scores across the whole mRS indicated that patients had a significant 1.56-fold improved chance of achieving a better score with thrombectomy than with tPA alone. Patients given thrombectomy also achieved higher rates of recanalisation at 24 hours than those treated with tPA, at 75.8% versus 34.1%.

However, Wardlaw and Dennis say that only about 7% of all ischaemic stroke patients, and 6% of all stroke patients admitted to hospital, are likely to be eligible for thrombectomy – in other words, those with no contraindications and a confirmed thrombus. They also note that thrombectomy is currently considered a highly specialist technique, rarely performed even in dedicated stroke centres, further limiting the number of patients who can currently benefit.

About 5% of patients in the meta-analysis had symptomatic intracranial haemorrhage, regardless of whether they received thrombectomy or tPA alone, and a respective 16.9% and 18.4% of patients in the treatment groups died.

The editorialists highlight several unanswered questions, including the influence of advanced age and comorbidities, and the time window in which thrombolysis can be undertaken; those in the studies ranged from 6 to 12 hours after symptom onset.

They add: “Studies also are needed to determine how to implement thrombectomy in routine practice, including testing the thorny question of who should perform the procedure, and whether the balance of benefit, cost, and service efficiency favor treating just those patients who individually will gain most or treating all patients with a reasonable chance of some worthwhile benefit.”

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