Dual Mechanisms of Ischemic Stroke: Frequency & Outcome in a University Hospital based Stroke Registry

Abstract Background: Ischemic stroke (IS) is a heterogeneous condition with varied mechanisms. Some patients have more than one stroke mechanism underlying the incident stroke. This study aimed to examine the association of dual stroke mechanisms among ischemic stroke patients with risk factors and clinical outcomes. Methods: Case records of adult patients with IS diagnosed using TOAST criteria in a University Stroke-Registry were reviewed for presence of dual IS mechanisms- viz. combinations involving small vessel disease(SVD), cardio-embolism(CE), or large artery atherosclerosis(LA). Outcomes were classified as good (modified Rankin Score=0-3) or poor (4-6). Univariate and multivariate methods of analysis were used. Results: Among 1220 patients with IS (age: 64+13 years; M:F::63%:37%), 177(14.5%) had an additional mechanism of stroke. SVD(51%) was the most common second mechanism, while CE(23%) and LA stroke(25%) were similar in frequency. On univariate analysis, patients with dual stroke mechanisms were significantly older(p<0.001), had higher frequency of conventional risk factors (p<0.007), abnormal brain MRI(p=0.004) and worse outcomes(p=0.058). On logistic regression analysis, poor outcomes at hospital discharge or 12 month follow-up were independently associated with: older age(p=0.007); female gender(p=0.017); poor sensorium(p<0.001); and type of primary stroke(p<0.001). Conclusions: Up to one in seven patients with ischemic stroke may have an additional mechanism of stroke. Such patients are likely older, with poorly controlled risk factors, worse sensorium and possible worse outcomes. Small vessel disease is the most common additional stroke mechanism. Studies to explore the influence of dual stroke mechanisms on outcomes as well strategies for secondary prevention are indicated.