- History (within last 6 months) of significant cardiovascular disease unless the disease is well-controlled. Significant cardiac disease includes second/third degree heart block; clinically significant ischemic heart disease; superior vena cava (SVC) syndrome; poorly controlled hypertension; congestive heart failure of New York Heart Association (NYHA) Class II or worse (slight limitation of physical activity; comfortable at rest, but ordinary physical activity results in fatigue, palpitation, or dyspnea)