Measurement of myocardial blood flow with positron emission tomography before and after transmyocardial laser revascularization

Background - Transmyocardial laser revascularization (TMLR) has been proposed for treatment of refractory angina. It has been hypothesized that transmural left ventricular channels created by laser improve myocardial blood flow (MBF) in the treated zones. We aimed to assess the effect of TMLR on MBF and coronary vasodilator reserve (CVR). Methods and Results - We measured MBF by means of PET with ¹⁵O-labeled water in 7 patients with refractory angina, Canadian Cardiovascular Society (CCS) class 3.6±0.5, on 3 occasions: before and at 7.5±2.8 weeks (FU-1) and 34.6±4.7 weeks (FU-2) after TMLR performed with a synchronized, high-powered CO₂ laser. In each study, MBF was measured at rest and during maximal intravenous dobutamine. CVR was computed as dobutamine divided by resting MBF. After TMLR, CCS class was 2.2±1.7 at FU-1 and 2.4± 1 at FU-2 (P=0.04 versus pre-TMLR). Resting MBF in both lasered and nonlasered regions was unchanged after TMLR. Dobutamine MBF at baseline was 1.45±0.52 and 1.55±0.52 mL · min^-1 · g^{- 1} in lasered and nonlasered regions, respectively (P=NS). At FU-1, dobutamine MBF in nonlasered regions had increased significantly to 1.89±0.82 mL · min^-1 · g^-1 (P-1, g^-1; P-1 · g^-1; P-1 · g^-1; P