CLEVELAND — In the operating room at the Cleveland Clinic, Dr. Brian Fitzsimons has long relied on a decades-old drug to prevent hemorrhages in patients undergoing open-heart surgery. The drug, aminocaproic acid, is widely used, cheap and safe. “It never hurt,†he said. “It only helps.†Then manufacturing issues caused a national shortage. “We essentially did military-style triage,†said Dr. Fitzsimons, an anesthesiologist, restricting the limited supply to patients at the highest risk of bleeding complications. Those who do not get the once-standard treatment at the clinic, the nation’s largest cardiac center, are not told. “The patient is asleep,†he...