Transmyocardial laser revascularization(TMR) has been used in treating patients with coronary artery disease either as sole treatment or in combination with coronary artery bypass surgery(CABG). Myocardial perfusion imaging(MPI) with thallium-201 has been used for assessment of perfusion post TMR, however Technetium-99m(Tc99m)is currently the standard. No studies have evaluated the use of Tc99m in patients who have received TMR with CABG. We evaluated the utility of Tc99m MPI summed stress scores (SSS) and correlation of clinical symptoms in TMR patients.
97 patients had TMR with CABG from 1998 to 2002. 12 were selected for review based on the availability of post-operative MPI. Studies were reviewed by a nuclear cardiologist and given a SSS based on the standard 17-segment scoring system. Canadian Cardiovascular Society(CCS) angina scores were obtained in all patients pre- and post-operatively, and end points were assessed including myocardial infarction(MI), need for post operative revascularization procedures, and death. These findings were correlated with the Tc99m MPI SSS.
Patients received MPI on average of 12 months postoperatively. Average age was 59 and an average CCS of 3.6. 64% had hypertension, 36% diabetes, 82% dyslipidemia, 36% had prior MI and 54% tobacco use. Postoperatively, 50% required diagnostic cardiac catheterization, of those only 2 patients required further revascularization. Postoperatively, all patients reported an improvement and 67% had complete resolution of symptoms; an average CCS of 2.6. The overall SSS was 14 and the TMR segments had higher average SSS per segment 3.2 versus the grafted areas with SSS 1.8. No new MIs or deaths occurred.
Tc99m MPI is a useful tool in predicting long term clinical outcomes in CAD patients. However, even with the increased sensitivity of Tc99m, which may identify more subtle abnormalities over previous isotopes, no improvement was found in the TMR segments. Discordance between SSS in the TMR segments and symptom improvement are consistent with prior studies utilizing thallium-201.
Symptom improvement may occur with TMR, but Tc99m MPI does not reveal improvement of ischemia.
V.K. Verma, None.