Beyond helping to guide therapy, MCI flow also was tightly linked to collateral flow.
Microcatheter contrast injection (MCI) is safe when used during mechanical thrombectomy and does not appear to increase the risk of intracranial hemorrhage, according to a new subanalysis of the SWIFT PRIME data. In addition to helping guide therapy, MCI flow correlated strongly with collateral flow.
During the era of intra-arterial thrombolysis, MCI was linked to an uptick in hemorrhage risk and contrast extravasation, Italo Linfante, MD (Herbert Wertheim College of Medicine and Baptist Hospital, Miami, FL), told Neurovascular Exchange. “Because the world has changed since the time we were using intra-arterial thrombolysis, the investigators wanted to see if it is safe to do MCI in the current mechanical thrombectomy era,” explained Linfante, who was not involved in the study.
For their subanalysis published online November 16, 2017, ahead of print in the Journal of NeuroInterventional Surgery, Radoslav Raychev, MD (University of California, Los Angeles), and colleagues used data from the SWIFT PRIME trial to correlate preintervention MCI flow with collateral flow. Next, they evaluated its impact on intracranial hemorrhage and outcome after thrombectomy using the Solitaire device (Medtronic).
Overall, 51 of 98 patients (52%) in the stent-retriever thrombectomy arm of the trial received MCI. In 71% of these patients, the microcatheter was positioned in the M2. There was a strong inverse correlation between the presence of partial collaterals and good MCI flow (OR 8.25; P = 0.004).
There was no relationship between MCI variables (presence, number, or grade) and intracranial hemorrhage or clinical outcome. The most significant predictors of nondisabled outcome were higher ASPECTS (OR 1.61, P = 0.0361) and younger age (OR 0.922, P = 0.0109). Higher ASPECTS also strongly predicted lower risk of intracranial hemorrhage (OR 0.501, P = 0.0078).
‘Safe and Useful’
According to these findings, “MCI is safe and useful. Practitioners should not hesitate to perform it,” Raychev told NVX in an email. “The study rebuts the previous notion that MCI promotes hemorrhage. Also, we found that distal emboli may be present even prior to thrombectomy, which has not been reported.”
MCI, in the context of thrombectomy, can help operators “to avoid inappropriate deployment and to optimize the efficacy of the procedure,” he concluded. “Our findings also provide platform for safe delivery of neuroprotective medications via MCI during thrombectomy.”
Linfante agrees that MCI can be a useful tool. “For example, if we are planning to do mechanical thrombectomy in a small vessel or on a tight bifurcation of two vessels,” he explained, “you want to know where you are going to land with your thrombectomy device. Also, it can give you an idea of how big the clot burden is.” It is particularly helpful for more distal occlusions, he added.
To NVX, Raychev acknowledged that the subanalysis is limited by its small sample size and by the fact that different operators often use different techniques.
“Of course, the more data we have, the better it is,” said Linfante. But he added that he agrees with the authors’ conclusion that MCI certainly appears to be safer today, in the era of mechanical thrombectomy, than it was in the era of intra-arterial thrombolysis.
Also interesting is that MCI flow correlated with collateral flow, Linfante noted, though he specified that this finding needs to be further validated. “Collateral flow is the Holy Grail of acute stroke treatment,” he said. So, reliable data on collateral flow can provide important information that can help determine prognosis and guide clinical care. He referred to the DAWN trial, which recently demonstrated that patients with good collateral flow can be treated up to 24 hours after symptom onset.
The findings are reassuring, said Linfante emphasized that MCI should still always be undertaken with extreme caution. “This has to be done very carefully. It cannot be done with a pressurized injection. You have to be very gentle, but compared to the past this shows that in the era of mechanical thrombectomy, we can [safely] do MCI, and it can give us a better road map for landing the thrombectomy device.”
Source:
Raychev R, Jahan R, Saver JL et al. Microcatheter contrast injection in stent retriever neurothrombectomy is safe and useful: insights from SWIFT PRIME. J NeuroInterv Surg. 2017;Epub ahead of print.
Disclosures:
- Raychev reports no relevant conflicts of interest.
- Linfante reports being an investigator in the SWIFT PRIME study.
