IMS III Substudy Identifies Reasons for Endovascular Treatment Delays in Acute Stroke Patients

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A subanalysis of the Interventional Management of Stroke (IMS) III trial found substantial delays prior to reperfusion in acute stroke patients. The study, published online May 9, 2014, ahead of print in Circulation, showed that delays decreased as the trial progressed and that patients who received computed tomographic angiography (CTA) and endovascular treatment in the same center had fewer delays.

The randomized IMS III trial was halted after an interim analysis found that endovascular treatment (catheter-delivered thrombolysis or a stent retrieval device) failed to improve outcomes for acute stroke patients when used as add-on therapy after IV infusion of tissue plasminogen activator (t-PA). The results were published in the March 7, 2013, issue of the New England Journal of Medicine.

For the substudy, researchers led by Mayank Goyal, MD, of the University of Calgary (Calgary, Canada), looked at the following time intervals in the endovascular arm:

• Stroke onset to ED arrival (n = 418)
• ED arrival to CT (n = 413)
• CT to IV t-PA start (n = 412)
• IV t-PA start to randomization (n = 417)
• Randomization to groin puncture (n = 407)
• Groin puncture to thrombus identification (n = 327)
• Thrombus identification to start of endovascular therapy (n = 310)
• Start of endovascular therapy to reperfusion (n = 312)

The largest delays were seen in the intervals from IV t-PA to groin puncture (median 85 minutes) and from start of endovascular therapy to reperfusion (median 85 minutes).

Transfer status increased the time from IV t-PA to groin puncture, largely driven by the time from randomization to puncture, compared with patients treated entirely at 1 facility (table 1). Additionally, the odds of a good clinical outcome (modified Rankin Scale score ≤ 2) were worse for transferred patients compared nontransferred patients (OR 0.56; 95% CI 0.31-0.99; P = .045). This association was not maintained after adjustment for baseline CTA, age, baseline NIHSS or ASPECTS scales, or reperfusion status.

Table 1. Time Intervals by Transfer Status

There was no difference in the time from IV to puncture in patients who were treated under the paradigm of transport before IV thrombolysis compared to those who were randomized and treated in the same facility.

While prerandomization CTA was not mandatory, its use (49.5%) shortened median CT to IV t-PA times by 8 minutes. Patients who underwent CTA or MRA had a slightly higher proportion of proximal occlusions compared with those who received CT alone (P < .05).

Median CT to groin puncture time was shorter during working hours (Monday-Friday 08:00-17:00) than afterward (119 vs 141 minutes; P < .0001). Additionally, those randomized during daylight hours (08:00-21:00) had shorter CT to groin puncture times than those treated at night (127 vs 142 minutes; P = .0012).

The times from ED arrival to reperfusion and groin puncture to reperfusion improved over the course of the trial (table 2).

Table 2. Time Intervals Throughout the Trial Period

 
Independent predictors of delay from ED arrival to reperfusion in 261 patients treated at a single center were:

• No CTA use (20 minutes; P = .008)
• Treatment outside of working hours (15 minutes; P = .03)
• First vs last quartile enrollment in the trial (46 minutes; P < .0001).

Age, sex, baseline NIHSS, and intubation status had no impact on delays.

Potential for Improvement

Dr. Goyal and colleagues explain that some of the endovascular procedure-related delays could be device related. “The current first choice endovascular devices, [stent retrievers], were used in only [a] few patients in the endovascular arm, which may have affected both the success and speed of reperfusion,” they write. “With the increasing use of [stent retrievers] and the progressively short puncture to reperfusion times reported, endovascular procedures are already shorter and yield higher rates of successful reperfusion.”

Additionally, the authors suggest a solution of cross-training X-ray and CT techs to assist in the angiography suite outside of normal working hours, a strategy that would still require “other members of the interventional team [to be] also readily available. This could be addressed by establishing a group alert paging system which links members of the stroke and interventional teams to provide enough time to travel to the hospital as IV t-PA is being administered.”

Ultimately, they conclude, “[t]hese data may help in designing, optimizing, and documenting workflow in current and future endovascular trials.”

 

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Source:
Goyal M, Almekhlafi MA, Fan L, et al. Evaluation of interval times from onset to reperfusion in patients undergoing endovascular therapy in the IMS III trial. Circulation. 2014;Epub ahead of print.

 

 

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