Association between Prior Cytomegalovirus Infection and the Risk of Restenosis after Coronary Atherectomy

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Abstract
The association between seropositivity for cytomegalovirus (CMV) and restenosis after coronary atherectomy reported by Zhou et al. (Aug. 29 issue)1 is intriguing, but their analysis leaves open several questions. The authors included four patients in the CMV-positive group who, though initially seropositive, were seronegative at the six-month follow-up visit. Three of these patients had initial CMV titers just above the cutoff for seropositivity, whereas one had a midrange titer; all the titers dropped to nearly zero on follow-up. This raises the question of whether these patients in fact had CMV infection.2 Since they all had restenosis, including them in the CMV-positive category has substantial bearing on the results. Had the infections been classified on the basis of the results of serologic testing at six months rather than before atherectomy, our calculations suggest that CMV would not have been identified as a risk factor for restenosis (odds ratio, 2.4; 95 percent confidence interval, 0.7 to 8.3). Given the uncertainty of these patients' CMV status, it would seem prudent at a minimum to omit them from the analysis.