RESUMO
AIM: It has been shown that exercise may lead to the myocardial stunning with reduction of LVEF, persisting for some time despite recovery of perfusion. The aim of this study was to check whether the post-stress decrease of LVEF lasts as long as 3 h after exercise. PATIENTS, METHODS: The study was performed in 46 patients with CAD and in 10 normals (NMS). All patients underwent myocardial gSPECT after (99m)Tc-tetrofosmin injection at rest and during stress with 2-day protocol. SPECT was started 1h after tracer injection at rest (R) and twice: 1h (S1) and 3hs (S3) after injection at stress. LVEF was calculated by the method of Germano et al. RESULTS: All LVEF values were significantly lower in CAD patients than in the control group. In NMS mean LVEF was at rest similar to those obtained 1 h and 3 h after stress injection (59.0 +/- 4.1, 60.0 +/- 5.9, 58.0 +/- 4.6, respectively; p >0.05). A post-exercise decrease of LVEF was observed in 2 normal patients both at S1 and at S3. In CAD group LVEF values were lower at S1 than at R (50.8 +/- 13.6 versus 49.3 +/- 12.8; p <0.05) and at S3 were lower than at S1 (49.3 +/- 12.8 versus 46.0 +/- 12.2;p <0.001). A significant decrease of LVEF was found in 18/46 patients 1 h post stress and in 36/46 3 h post stress. In patients with reversible perfusion decrease, a significant correlation was found between post-exercise deterioration of perfusion and post-exercise LVEF reduction both at S1 (r = 0.744; p <0.02) and at S3 (r = 0.734; p <0.02). Stress induced decrease in LVEF correlated also with severity of perfusion abnormalities. CONCLUSIONS: In the majority of patients with CAD physical stress applied for diagnostic purposes results in an impairment of the LV function. A decrease of the LVEF is observed 1 h after exercise, but it increases in frequency and grows stronger during the next 2 h. The post-stress LVEF reduction is related to the severity of perfusion abnormalities. Patients with CAD who underwent diagnostic stress test should remain under observation during several hours after termination of exercise.
