Cerebral microbleeds development after stroke thrombolysis: A secondary analysis of the THAWS randomized clinical trial

Kaori Miwa, Masatoshi Koga, Manabu Inoue, Sohei Yoshimura, Makoto Sasaki, Yusuke Yakushiji, Mayumi Fukuda-Doi, Yasushi Okada, Taizen Nakase, Masafumi Ihara, Yoshinari Nagakane, Shunya Takizawa, Koko Asakura, Junya Aoki, Kazumi Kimura, Haruko Yamamoto, Kazunori Toyoda

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3 Citations (Scopus)


Background and aim: We determined to investigate the incidence and clinical impact of new cerebral microbleeds after intravenous thrombolysis in patients with acute stroke. Methods: The THAWS was a multicenter, randomized trial to study the efficacy and safety of intravenous thrombolysis with alteplase in patients with wake-up stroke or unknown onset stroke. Prescheduled T2*-weighted imaging assessed cerebral microbleeds at three time points: baseline, 22–36 h, and 7–14 days. Outcomes included new cerebral microbleeds development, modified Rankin Scale (mRS) ≥3 at 90 days, and change in the National Institutes of Health Stroke Scale (NIHSS) score from 24 h to 7 days. Results: Of all 131 patients randomized in the THAWS trial, 113 patients (mean 74.3 ± 12.6 years, 50 female, 62 allocated to intravenous thrombolysis) were available for analysis. Overall, 46 (41%) had baseline cerebral microbleeds (15 strictly lobar cerebral microbleeds, 14 mixed cerebral microbleeds, and 17 deep cerebral microbleeds). New cerebral microbleeds only emerged in the intravenous thrombolysis group (seven patients, 11%) within a median of 28.3 h, and did not additionally increase within a median of 7.35 days. In adjusted models, number of cerebral microbleeds (relative risk (RR) 1.30, 95% confidence interval (CI): 1.17–1.44), mixed distribution (RR 19.2, 95% CI: 3.94–93.7), and cerebral microbleeds burden ≥5 (RR 44.9, 95% CI: 5.78–349.8) were associated with new cerebral microbleeds. New cerebral microbleeds were associated with an increase in NIHSS score (p = 0.023). Treatment with alteplase in patients with baseline ≥5 cerebral microbleeds resulted in a numerical shift toward worse outcomes on ordinal mRS (median [IQR]; 4 [3–4] vs. 0 [0–3]), compared with those with <5 cerebral microbleeds (common odds ratio 17.1, 95% CI: 0.76–382.8). The association of baseline ≥5 cerebral microbleeds with ordinal mRS score differed according to the treatment group (p interaction = 0.042). Conclusion: New cerebral microbleeds developed within 36 h in 11% of the patients after intravenous thrombolysis, and they were significantly associated with mixed-distribution and ≥5 cerebral microbleeds. New cerebral microbleeds development might impede neurological improvement. Furthermore, cerebral microbleeds burden might affect the effect of alteplase.

Original languageEnglish
Pages (from-to)628-636
Number of pages9
JournalInternational Journal of Stroke
Issue number6
Publication statusPublished - 2022 Jul
Externally publishedYes


  • Ischemic stroke
  • cerebral microbleeds
  • cerebral small vessel disease
  • thrombolysis

ASJC Scopus subject areas

  • Neurology


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