Sirimarco et. al
. published an interesting paper recently looking at the overlap of associated conditions (A-atherothrombosis, S-small vessel disease, C-cardiac pathology, O-other uncommon causes) in a cohort series of 403 patients. They categorized how each of the these potential factors may have contribured to cause of stroke by 1-potential cause of stroke, 2-causality is uncertain, and 3-disease is present but unlikely to be a direct cause, 0-disease is not present, and 9-when workup is insufficient to determine relationship. They discovered (not surprisingly) that atherothrombosis was the most prevalent (90% having either A1-3 scores) and identified as the most frequent potentially causal underlying condition. Small vessel disease was also highly prevalent (66% S1-3) but the vast majority, it was of uncertain or not directly related to the stroke. Cardiac pathology sat somewhere in the middle. The overlap between atherothrombosis and cardiac pathology was the highest (25 patients had A1 and C1 scores). In long term follow up, those with cardiac pathology had the highest risk of any major vascular event (C1 having a hazard ratio of 5.3!)
While this is a novel categorization that helps identify the potential overlap of underlying premorbid conditions that may contribute to stroke mechanism, I am not certain how it would change our management. Certainly atherothrombosis, small vessel disease, and cardiac disease are all related to each other and have significant overlap in underlying vascular risk factors. Likewise, we would be treating patients with small vessel disease and atherothrombosis quite similarly. Cardiac pathology may alter our management, but previous guidelines and framework for evaluating patients would have addressed that already.
As the authors suggest, perhaps ASCOD grading would be more useful for studying genetics of stroke where overlap in contributing conditions maybe more important. Similarly, this classification scheme may be helpful in finding patients who may benefit from therapeutic trials who may otherwise be missed when using TOAST criteria.