Effects of time delays on the therapeutic outcomes of intravenous thrombolysis for acute ischemic stroke in the posterior circulation: An observational study

OBJECTIVES: We aim to demonstrate the effects of time delays on the therapeutic outcomes of intravenous thrombolysis (IVT) in acute posterior circulation stroke (PCS) patients. METHODS: Consecutive PCS cases treated with IVT alone were retrospectively examined. The primary end point was set to be a favorable outcome (modified Rankin Scale [mRS] ≤2) at 3 months, and angiographic recanalization was set to be the secondary outcome. RESULTS: A total of 95 PCS cases with IVT were recruited. The patients with favorable outcomes and those without favorable outcomes had similar baseline characteristics, except for significantly lower National Institute of Health Stroke Scale (NIHSS) scores (5 vs. 12, respectively; p < 0.001) and less hyperdense basilar artery signs in head CTs (26.5% vs. 70.4%, respectively; p < 0.001) for those with favorable outcomes. For patients with an onset‐to‐treatment time (OTT) of 0–90 min (n = 5), 91–180 min (n = 38), 181–270 min (n = 37), or ≧271 min (n = 15), the rate of favorable outcome was 100.0%, 71.1%, 67.6%, or 73.3%, respectively, and the Cochran–Armitage trend test showed no linear trend between the OTT and the clinical prognosis of IVT in PCS (p = 0.501) patients. In addition, the rates of recanalization were 100.0%, 68.4%, 64.9%, and 46.7%, and the Cochran–Armitage trend test suggested a linear trend between the OTT and recanalization (p = 0.046); that is, the proportion of PCS patients who underwent recanalization decreased with increasing OTTs. In the multivariate logistic regression analysis, after adjusting for confounding factors with p ≦ 0.20 in the univariate analysis, baseline NIHSS scores and hyperdense basilar artery signs were negatively associated with favorable outcomes, with odds ratios (OR) of 0.884 (95% confidence interval [CI], 0.804–0.971; p = 0.010) and 0.208 (95% CI, 0.062–0.693; p = 0.011), respectively. In addition, there was a negative association between recanalization, OTTs (OR, 0.993, 95% CI, 0.987–0.999; p = 0.029), and baseline NIHSS scores (OR, 0.881, 95% CI, 0.802–0.967; p = 0.008). CONCLUSION: Irrespective of stroke severity, the therapeutic effects of recanalization after IVT decreased significantly with longer time delays in PCS patients.