Rate of re-bleeding of arteriovenous malformations in the first year after rupture.

Prior rupture is an established risk factor for subsequent hemorrhage from arteriovenous malformations (AVM). Recent natural history studies have reinvigorated the important concept that the re-bleed rate is not constant; rather, it is particularly greater in the first year after hemorrhage. In this study, we reviewed our own cohort of 129 patients with AVMs. Eighty-one presented with hemorrhage (63%), and of these patients, 38 had at least one month of subsequent clinical follow-up and were included in our analysis. Over a total of 140 patient-years, the annual re-hemorrhage rate was 7.9%, though it was 15.8% in the first year. Two-thirds of those AVM that hemorrhaged in the first year were associated with aneurysms. The overall permanent morbidity of re-hemorrhage was 45%; the mortality rate was 9%. Although the re-hemorrhage rate in the first year varied from 6% to 15.8% across series in the literature, it was generally double the overall re-hemorrhage rate provided in each study. These results have significant therapeutic implications, favoring surgical treatment of ruptured AVM and/or their associated aneurysm when feasible to avoid the incumbent greater risk of early rehemorrhage.