To the Editor.
—A recent article in the Archives recommending bypass surgery for Prinzmetal angina deserves some comment (Bentiviglio et al, 136:313-316, 1974). Though localized stenosis of the coronary arteries1 is frequently demonstrated in variant as well as in classic angina, the additional occurrence of coronary artery spasm has been sometimes documented in variant angina pectoris.2-4 Likewise, coronary artery spasm has been documented in patients with variant angina and angiographically normal coronary arteries.5 The hemodynamic changes occurring with variant angina appear to differ from those occurring with classic angina. Patients with classic angina commonly exhibit an increase in the pressure-time index prior to spontaneous or induced angina. In contrast, patients with variant angina frequently do not exhibit an increase in the pressure-time index; in fact, it often falls during pain. These findings suggest that, at least in some cases of variant angina, the pain may be