Nifedipine-Induced Hypotension and Myocardial Ischemia in Refractory Angina Pectoris

To the Editor.— There are several scientific flaws in the recent article by Boden et al1discussing the proposed pathophysiologic mechanisms of paradoxical myocardial ischemia in the treatment of patients with refractory angina who are taking nifedipine coadministered with β-blockers or long-acting nitrates. The first problem is the basic study design. The authors studied a subset of patients who had experienced recurrent episodes of angina pectoris following nifedipine administration and, in an uncontrolled, nonrandomized, open fashion, evaluated each patient's response to study medications. Although the study attempted to investigate the pathophysiologic mechanisms of paradoxical angina, this uncontrolled design introduces both patient and investigator bias. Certainly, the patients' psychological and physiological response to a regimen that they expect will cause them pain must confound the validity of any results obtained from the trial. A second major problem is the apparent lack of nifedipine titration. Despite the fact that the patients