[Progression of coronary stenosis following aorto-coronary bypass surgery]

In a prospective study (238 men, mean age 53 years) the changes in native vessels were studied 3 months after aorto-coronary bypass operation and 5 months after preoperative angiography. Progression was defined as increase in stenoses of at least 20% or new total occlusion. Progression was significantly more frequent in vessels with bypass than without; it was located proximally to the anastomoses in most cases, less frequently at the anastomoses and very rarely distally to the anastomoses. Proximal progression was significantly more frequent with open bypasses than with occluded ones. Stenoses at the anastomoses were significantly more frequent with occluded bypasses than with open ones. More severe stenoses had a stronger tendency to progression than less severe stenoses. Regression was rare and nearly always caused by surgery.