Predictive Values of Gated Myocardial SPECT for Wall Motion Improvement After Bypass Surgery

게이트 심근 SPECT의 관동맥우회로술후 심근 벽운동 호전 예측능

We studied to investigate the predictive values of gated SPECT for the improvement of wall motion after bypass surgery. As we compared postoperative SPECT with preoperative ones, we defined viability as wall motion improvement. We peformed rest T1-201/s1ress Tc-99m-MIBI gated SPECT in 25 patients before and 3 months after bypass surgery. Myocardial wall motion was graded as normal, hypokinesia, akinesia, and dyskinesia by pair-wise visual analysis of gated pre and postoperative SPECT's on the same monitor screen. Myocardial wall thickening was determined good or poor Among 92 segments with wall motion abnormalities before operation, 69 (75%) improved and 23 did not. Before operation, we could find segments with good systolic thickening in 64 segments among total 92. Thickening of the remaining 28 was poor. Wall motion improved postoperatively in 45 segments (70%) among 64 with good thickening. Twenty four(86%) among 28 segments with poor thickening had also improved. We grouped segments into mild(hypokinetic) and severe(akinetic/dyskinetic) ones. Among 33 segments with severe motion abnormalities, 14 had good thickening and 19 did not. Nine(60%) improved out of 14 segments having severe abnormality with good thickening However, 16(84%) segments out of 19 haying severe abnormality with poor thickening also improved. Neither degree of perfusion decrease nor severity of wall motion abnormalities could explain the high rate of false negatives. In conclusion, as we defined viability as wall motion improvement by comparing pre and postoperative SPECT, systolic thickening observed by gated Tc-99m-MIBI SPECT in myocardial segments with wall motion abnormalities predicted wall motion improvement after bypass surgery. However, poor thickening could not be referred as evidence of nonviable myocardium both in mild and severe contractile dysfunction, so that we might need stimulation study such as dobutamine echocardiography or dobutamine gated SPECT.

이 연구에서 우리는 관동맥우회로술을 시행한 환자에서 수술 전에 게이트 심근 SPECT에서 심근벽의 수축기 두꺼워짐을 보아 수술 후 심근벽 운동이상의 호전을 예측할 수 있는지 조사하였다. 연구 결과 심근벽의 수축기 두꺼워짐이 좋은 분절은 생존심근이라 할 수 있었으나 심근벽의 수축기 두꺼워짐이 좋지 못하여도 생존심근이 아니라고 단정할 수 없었다. 심근벽 두꺼워짐 여부의 예측능은 심근 관류 감소의 중증도, 심근벽 운동 장애의 정도와 관련이 없었다. 게이트 심근 SPECT로 심근벽 두꺼워짐을 자극할 방법을 도입하고 자극 후 변화를 보는 방법으로 게이트 심근 SPECT를 시행하여 생존심근을 찾는 예민도와 음성예측율을 높일 필요가 있다.