Haemorrhagic transformation of ischaemic stroke: risk factors and prognostic implication

Abstract

Background: Haemorrhagic transformation (HT) complicating ischaemic stroke is associated with significant morbidities and mortality. The clinical implications of HT have not been explored locally. This study aimed to determine the risk factors and clinical implications of HT complicating cerebral infarction in the Hong Kong Chinese population. Methods: This was a retrospective case-control study of consecutive patients admitted to Queen Mary Hospital with acute ischaemic stroke (IS) between 1 January 2007 and 31 December 2011. HT was diagnosed with examination of repeated brain neuroimaging (computed tomography or magnetic resonance imaging) performed within 2 weeks of IS onset. Patients with IS without repeated neuroimaging within 2 weeks, and patients with transient ischaemic attack or intracranial haemorrhage were excluded. HT was classified according to the European-Australasian Acute Stroke Study (ECASS) II criteria. Poor clinical outcome was defined as mortality within 90 days or modified Rankin scale score >2 at completion of rehabilitation or around 90 days. Results: Of 718 patients recruited, 66 (9.2%) received intravenous (IV) thrombolysis and 117 (16.3%) developed HT—HI1, 12 (1.7%); HI2, 3 (0.42%); PH1, 46 (6.4%); PH2, 54 (7.5%); PH at remote site, 2 (0.28%). HT was independently predicted by IV thrombolytic therapy (odds ratio [OR]=2.86; 95% confidence interval [CI], 1.58-5.18), cardioembolic stroke (3.65; 2.23-5.97) and prior warfarin use (2.85; 1.27-6.39). At 90 days, 138 (19.2%) patients died. At completion of rehabilitation or around 90 days, 462 (64.3%) had poor outcome. The 90-day and 5-year mortality rates were significantly increased in patients with PH2 (hazard ratio=1.86; 95% CI, 1.07-3.24 and 1.53, 1.01-2.30, respectively). Multivariate analysis showed PH2 to be an independent predictor of poor outcome (OR=2.14; 95% CI, 1.04-4.40). Conclusion: IV thrombolytic therapy, cardioembolic stroke, and prior warfarin use were independent predictors of HT. PH2 was associated with increased risk of poor outcome at approximately 90 days and mortality at 5 years.