We assessed coronary reserve, by measuring the increase in coronary sinus blood flow (CSBF) after intravenous administration of dipyridamole (0.14 mgl kg/minute for 4 minutes), in 7 patients with primary scleroderma myocardial disease (PSMD) and in 7 control subjects. Coronary reserve was greatly impaired in PSMD: before administration of dipyridamole, CSBF was similar in patients with PSMD (89 f 32 mllminutel 100 gnn, mean f SD) and in controls (100 f 15 mll minutel100 gm); after dipyridamole infusion, CSBF was significantly lower in patients with PSMD (191 k 45 mll minutdl00 gm) than in controls (399 f 58 mllminutel 100 gm) (P < 0.01). Six of the 7 patients with PSMD had angiographically normal epicardial coronary arteries and normal left ventricular function. Decreased coro--~~

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