Cluster analysis of arterial involvement in Takayasu arteritis reveals symmetric extension of the lesions in paired arterial beds.

OBJECTIVE: The determinants of vessel targeting are largely unknown in vasculitides. This study was undertaken to identify patterns of vascular involvement in Takayasu arteritis (TA), using objective classification of vascular beds. We postulated that cluster analysis could unveil preferential associations between vascular beds commonly affected by TA.
METHODS: Peripheral vascular Doppler, computed tomography angiography, and angio-magnetic resonance imaging data from 82 patients with TA (according to the American College of Rheumatology criteria) were studied between January 1995 and May 2006. Cross-relationships of involvement between 24 main arteries were assessed using the phi correlation coefficient. Identification of patterns of vascular involvement was performed using agglomerative hierarchical cluster analysis.
RESULTS: Data were obtained from 82 patients (68 women [82.9%] and 14 men [17.1%]). The median duration of followup was 5.1 years (range 1 month to 30 years). For 16 (80%) of 20 paired arteries, the highest correlation of involvement was observed with the contralateral artery. Conversely, disease extension was contiguous in the aorta. Cluster analysis further confirmed that all paired arterial beds, except for the internal and external carotid arteries, clustered with their contralateral counterpart and that the aortic arch, the descending thoracic aorta, and the abdominal aorta clustered together.
CONCLUSION: Our findings reveal that TA lesions mostly develop in a symmetric manner in paired vascular territories and that disease extension is contiguous in the aorta. This may prove useful for improving the radiologic followup of patients with TA and for providing a pattern for further investigations focusing on the mechanisms of vessel specificity in vasculitides.