Session P72.1

Analysis of High-Frequency QRS Components Improves the Detection of Ischemic Heart Disease Compared to Conventional ST Analysis

E Toledo, J Lipton, SG Warren, S Abboud*,
M Broce, DR Lilly, GS Wagner

Tel Aviv University
Tel Aviv, Israel

Exercise ECG is considered the initial diagnostic evaluation of choice of ischemic heart disease (IHD). However, it was shown in numerous studies that the diagnostic performance of exercise ECG in detecting IHD is limited. In this study we analyzed the depolarization-related, high-frequency components of the QRS complex to examine the diagnostic performance of this technique in detecting stress-induced ischemia. Our aims were to validate (i) this technique in patients undergoing exercise myocardial perfusion imaging (MPI) using SPECT and (ii) compare its performance with conventional ECG.
Methods: Exercise MPI was performed in 133 consecutive pts (63±12 yo, 100 men) and used as the gold standard for ischemia. Pts with BBB (n=20), inconclusive MPI (n=4) or with technical problems in ECG recordings (n=8) were excluded. Conventional ECG was combined with high resolution ECG acquisition that was digitized and analyzed using the HyperQ™ System (BSP, Tel Aviv, Israel). The relative HFQRS intensity change during exercise was used as an index of ischemia.
Results: Of the 101 patients that were included in the analysis, 19 exhibited MPI ischemia. The HFQRS index of ischemia was found more sensitive (79% vs 41%, p<0.05) and more specific (71% vs 57%, p<0.05) than conventional ST analysis. In women, HFQRS analysis resulted in markedly enhanced specificity relative to conventional ECG (70% vs 33%, p<0.05). In patients with prior MI, HFQRS analysis was more sensitive than ST analysis (80% vs. 36%, p<0.05). The specificity of HFQRS analysis in this group was similar to that of the entire group (69%). In patients with inconclusive ST changes, HFQRS analysis correctly identified 17/21 pts.
Conclusions: HFQRS analysis was more accurate in detecting stress-induced ischemia and exhibited improved diagnostic performance in women as well as other subgroups.

(Abstract Control Number: 32)