Background: Quantifying the magnitude of benefit of mechanical thrombectomy (MT) add to IV tPA (IVT) versus IV tPA alone vs neither in patients with acute ischemic stroke due to large vessel occlusion (LVO-AIS) is crucial to optimal organization of regional systems of stroke care. But single RCT analysis cannot quantify these effect magnitudes as no IV tPA trial enrolled explicitly-identified LVO patients, and no thrombectomy trial enrolled early IV tPA responders.
Methods: We performed a matched patient network analysis of the two NINDS-tPA trials and the SWIFT PRIME trial. Using 1:1 optimal inverse variance matching, with NIHSS ± 1 and age ± 5, triplet matched were made between the NINDS placebo (neither MT or IVT), NINDS tPA (tPA only), and SWIFT PRIME (MT+IVT) treatment groups, ensuring comparable LVO-AIS patients, and 90 day mRS outcomes analyzed.
Results: Among 258 triplet matched patients (86 in each treatment arm), baseline characteristics were well balanced for age (MT+IVT 66.6, IVT only 66.5, neither 66.7, p=1.00) and presenting deficit severity (NIHSS 16.3 vs 16.4 vs 16.2, p=0.98). Dramatic early benefits of IVT, leading to foregoing of MT, occurred in 10.1% of patients. The Figure shows final 90 day mRS distributions for the 3 AIS-LVO treatment strategies. Freedom from disability (mRS 0-1) was higher with MT+IVT than IVT alone and neither (47.7% vs 31.4% vs 19.8%), as was functional independence (mRS 0-2, 64.2% vs 37.2% 30.2%), and severe disability/death (mRS 5-6) was lower (11.0% vs 29.1% vs 31.4%). Number needed to treat for 1 improved outcome over the entire mRS range (shift analysis) was 4.9 for IVT alone vs neither and 2.0 for both MT+IVT vs neither.
Conclusions: The strategy of IV thrombolysis plus direct mechanical thrombectomy unless immediate dramatic benefit occurs is highly power for LVO-AIS, improving outcomes in 1 of every 2 patients. IVT alone provides benefit in 1 in 5 patients.