Reactive Hyperemia Revisited
We thank Calderaro et al for their interest in our work. They provide interesting data from their unpublished study that examined the relation between measures of vascular function and adverse events in a cohort of 96 patients undergoing vascular surgery. Similar to our findings, they report that reactive hyperemia is lower in patients with postoperative events compared to patients without an event. In contrast to our study, however, they observed no significant difference in brachial artery flow-mediated dilation between groups. This apparently discrepant result could result from a variety of factors, including differences in the patient population and the methodology used to assess vascular function. In addition, we respectfully point out that our sample size (267 patients) and number of events (50) was substantially larger, and we therefore had more statistical power to detect a difference in flow-mediated dilation between groups. We strongly concur with the authors that reactive hyperemia is an important and previously under-recognized aspect of vascular function that may be relevant to the pathogenesis of cardiovascular events. Measures of reactive hyperemia may have potential as method to assess cardiovascular risk.