Electromechanical mapping versus positron emission tomography and single photon emission computed tomography for the detection of myocardial viability in patients with ischemic cardiomyopathy

OBJECTIVES: We compared catheter-based electromechanical mapping (NOGA system, Biosense-Webster, Haifa, Israel) with positron emission tomography (PET) and single photon emission computed tomography (SPECT) for prediction of reversibly dysfunctional myocardium (RDM) and irreversibly dysfunctional myocardium (IDM) in patients with severe left ventricular dysfunction. Furthermore, we established the optimal discriminatory value of NOGA measurements for distinction between RDM and IDM. BACKGROUND: The NOGA system can detect viable myocardium but has not been used for prediction of post-revascularization contractile function in patients with ischemic cardiomyopathy. METHODS: Twenty patients (19 males, age [mean ± SD] 60 ± 16 years, ejection fraction [EF] 29 ± 6%) underwent viability testing with NOGA and PET or SPECT before revascularization. Left ventricular function was studied at baseline and six months after revascularization. RESULTS: The EF increased to 34 ± 13% at six months (p < 0.05 vs. baseline). The 58 RDM and 57 IDM regions differed with regard to unipolar voltage amplitude (UVA) (9.2 ± 3.9 mV vs. 7.6 ± 4.0 mV, p < 0.05), normalized UVA (106 ± 54% vs. 75 ± 39%, p < 0.05), and tracer uptake (76 ± 17% vs. 60 ± 20%, p < 0.05). The NOGA local shortening did not distinguish between RDM and IDM (6.4 ± 5.8% vs. 5.4 ± 6.6%). By receiver operating characteristic curve analysis, myocardial tracer uptake had better diagnostic performance than UVA (area under curve [AUC] ± SE: 0.82 ± 0.04 vs, 0.63 ± 0.05, p < 0.05) and normalized UVA (AUC ± SE: 0.70 ± 0.05, p < 0.05). Optimal threshold was defined as the value yielding sensitivity = specificity for prediction of RDM. Sensitivity and specificity were 59% at a UVA of 8.4 mV, 65% at a normalized UVA of 83%, and 78% at a tracer uptake of 69%. CONCLUSIONS: The NOGA system may discriminate RDM from IDM with optimal discriminatory values for UVA and normalized UVA of 8.4 mV and 83%, respectively. However, the diagnostic performance does not reach the level obtained by PET and SPECT in patients with severe heart failure.