Normal values of cardiac mechanical synchrony parameters using gated myocardial perfusion single-photon emission computed tomography: Impact of population and study protocol

Purpose of the Study: Normal values of cardiac mechanical synchrony parameters in gated myocardial perfusion single-photon emission computed tomography (GMPS) are well established in literature from the Western population. The aim of the study is to establish normal values of mechanical synchrony with GMPS in Indian population and to find out whether it differs significantly from established values. Procedure: We retrospectively analyzed 1 day low-dose stress/high-dose rest GMPS studies of 120 patients (sixty males, 52 +/- 11.7 years) with low pretest likelihood of coronary artery disease and having normal GMPS study. In GMPS, first-harmonic fast Fourier transform was used to extract a phase array using commercially available software. Phase standard deviation (PSD) and phase histogram bandwidth (PHB) were used to quantify cardiac mechanical dyssynchrony. Results: The values obtained were as follows, PSD: In men, 14.3 +/- 4.7 (stress) and 8.9 +/- 2.9 (rest), in women 11 +/- 4 (stress) and 7.7 +/- 2.7 (rest), and PHB: In men, 40.1 +/- 11.9 (stress) and 30.6 +/- 7.6 (rest), in women, 34.7 +/- 12.6 (stress) and 25.3 +/- 8.6 (rest). The value of PSD and PHB was significantly less in Indian population as compared with established values in literature. We also observed that synchrony indices derived from the low-dose stress studies are higher than high-dose rest studies. Conclusions: The value of synchrony parameters differs significantly according to population and methodology suggesting that specific population and methodology-based normal database for assessment of cardiac mechanical dyssynchrony should be established.