Eighty-eight coronary patients were examined, 75.8% of them were exposed to multiple aortocoronary bypass surgery. Impaired left-ventricular myocardial contractile function was found in 91.6% of patients, in 60% of them reduced segmental activity was associated with compensatory hyperfunction of the intact segments. A sufficiently clear-cut correlation was revealed between reduction of left-ventricular segmental activity and involvement of the coronary bed and its reserve, as well as between ejection fraction and systolic output. Signs of latent cardiac insufficiency were detected in 42% of these patients. Compensatory hyperfunction of left-ventricular intact segments was as a rule combined with a positive assessment of patients' clinical status and intact coronary and myocardial reserve. Accurate analysis of left-ventricular segmental activity reduction including the mechanism of compensation for this reduction helps correctly select coronary patients for aortocoronary bypass surgery and adequately prepare them for this operation.