Cardiac workup of ischemic stroke: can we improve our diagnostic yield?

The Causative Classification of Stroke system: an international reliability and optimization study

BACKGROUND

Valid and reliable ischemic stroke subtype determination is crucial for well-powered multicenter studies. The Causative Classification of Stroke System (CCS, available at http://ccs.mgh.harvard.edu) is a computerized, evidence-based algorithm that provides both causative and phenotypic stroke subtypes in a rule-based manner. We determined whether CCS demonstrates high interrater reliability in order to be useful for international multicenter studies.

METHODS

Twenty members of the International Stroke Genetics Consortium from 13 centers in 8 countries, who were not involved in the design and development of the CCS, independently assessed the same 50 consecutive patients with acute ischemic stroke through reviews of abstracted case summaries. Agreement among ratings was measured by kappa statistic.

RESULTS

The κ value for causative classification was 0.80 (95% confidence interval [CI] 0.78-0.81) for the 5-subtype, 0.79 (95% CI 0.77-0.80) for the 8-subtype, and 0.70 (95% CI 0.69-0.71) for the 16-subtype CCS. Correction of a software-related factor that generated ambiguity improved agreement: κ = 0.81 (95% CI 0.79-0.82) for the 5-subtype, 0.79 (95% CI 0.77-0.80) for the 8-subtype, and 0.79 (95% CI 0.78-0.80) for the 16-subtype CCS. The κ value for phenotypic classification was 0.79 (95% CI 0.77-0.82) for supra-aortic large artery atherosclerosis, 0.95 (95% CI 0.93-0.98) for cardioembolism, 0.88 (95% CI 0.85-0.91) for small artery occlusion, and 0.79 (0.76-0.82) for other uncommon causes.

CONCLUSIONS

CCS allows classification of stroke subtypes by multiple investigators with high reliability, supporting its potential for improving stroke classification in multicenter studies and ensuring accurate means of communication among different researchers, institutions, and eras.

Stroke in younger patients: the heart of the matter

Stroke in young adults is not a rare entity, and often provides difficult management decisions for neurologists. The knowledge gained from stroke in older adults does not transfer easily to this younger group given the different causes of stroke observed. Cardiac causes of stroke are common in this group, but often consist of low risk cardiac lesions such as a patent foramen ovale. Appropriate investigation should follow a stepwise approach to initially exclude higher risk pathology for recurrent stroke such as arterial dissection. Similarly, stepwise application of cardiac investigations will allow early identification of significant pathology, with investigation for abnormalities of the inter-atrial septum reserved for those with no other identified cause of stroke. Bubble contrast echo is now widely available, and with improved image quality may be performed with either transthoracic or transoesophageal echo, as well as with transcranial Doppler. Following this approach, patients can be best categorised by the expected rate of recurrent stroke, as informed by observational studies. Appropriate secondary prevention can then be tailored to the recurrence rate, with anticoagulation and possibly device closure reserved for those at highest risk of recurrence.