All ACE Inhibitors Are Not Alike-Reply

In Reply.—  The comments by Cheng are quite valid and further emphasize the differences between various angiotensin-converting enzyme inhibitors. Although the presence of the sulfhydryl group in captopril has been shown to contribute to captopril's capacity to act as a free radical scavenger,¹² the clinical significance of this phenomenon is not established. In the study by McMurray et al,² the investigators evaluated 29 patients with chronic congestive heart failure by measurement of plasma malondialdehyde (an indirect indicator of free radical-mediated damage to lipids) and demonstrated that, compared with (Continued from p 1670.) healthy control subjects, the patients with congestive heart failure had higher plasma malondialdehyde and lower thiol concentrations (P<.05). Although it is true that increased free radical activity in patients with congestive heart failure may have important implications since free radicals cause impairment of myocyte metabolism and contraction,³ there is as yet little available information