Coexisting Dual Mechanisms of Ischaemic Stroke: Frequency and outcomes in a university hospital-based stroke registry.

Objectives: Ischaemic stroke (IS) is a heterogeneous condition with varied mechanisms. Some patients have more than 1 stroke mechanism coexisting, irrespective of the mechanism of the incident stroke.~This study aimed to examine the association of coexisting dual stroke mechanisms among IS patients with risk factors and clinical outcomes.

Methods: This retrospective study included adult patients with IS diagnosed using the TOAST criteria in Sultan Qaboos University Hospital's stroke registry who were admitted and treated from January 2011 to December 2020. The records were reviewed for the presence of dual IS mechanisms (combinations involving small vessel disease [SVD], cardioembolism [CE] or large artery atherosclerosis [LA]). Outcomes were classified as modified Rankin score (mRS) = 0-3 (favourable) or mRS = 4-6 (poor). Univariate and multivariate methods of analysis were used.

Results: Among 1,220 patients with IS (age = 64 ± 13 years; male:female = 63:37), 177 (14.5%) had an additional mechanism of stroke. The most common second mechanism was SVD (53.1%), while CE stroke (23.7%) and LA stroke (23.2%) were similar in frequency. Patients with dual stroke mechanisms were significantly older (P <0.001), had a higher frequency of conventional risk factors (P <0.007), abnormal brain magnetic resonance imaging (P = 0.004) and worse outcomes (P = 0.058). 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 1 in 7 patients with IS may have an additional mechanism of stroke. Such patients are likely older, with poorly controlled risk factors, worse sensorium and possibly worse outcomes. SVD is the most common additional stroke mechanism. Studies to explore the influence of dual stroke mechanisms on outcomes, as well as strategies for secondary prevention, are indicated.