The assessment of left ventricular mechanical dyssynchrony from gated 99mTc-tetrofosmin SPECT and gated 18F-FDG PET by QGS: a comparative study

Background Due to partly conflicting studies, further research is warranted with the QGS software package, with regard to the performance of gated FDG PET phase analysis as compared to gated MPS as well as the establishment of possible cut-off values for FDG PET to define dyssynchrony. Methods Gated MPS and gated FDG PET datasets of 93 patients were analyzed with the QGS software. BW, Phase SD, and Entropy were calculated and compared between the methods. The performance of gated PET to identify dyssynchrony was measured against SPECT as reference standard. ROC analysis was performed to identify the best discriminator of dyssynchrony and to define cut-off values. Results BW and Phase SD differed significantly between the SPECT and PET. There was no significant difference in Entropy with a high linear correlation between methods. There was only moderate agreement between SPECT and PET to identify dyssynchrony. Entropy was the best single PET parameter to predict dyssynchrony with a cut-off point at 62%. Conclusion Gated MPS and gated FDG PET can assess LVMD. The methods cannot be used interchangeably. Establishing reference ranges and cut-off values is difficult due to the lack of an external gold standard. Further prospective research is necessary.

The Effect of Clinical Characteristics and Stent Parameters on Left Ventricular Mechanical Dyssynchrony

Aim. To study short term effect of stent size and number on left ventricular mechanical dyssynchrony after elective percutaneous coronary intervention (PCI) to left anterior descending (LAD) artery.Materials and methods. the study included 150 adult patients with LAD lesion treated with PCI using drug-eluting stent. Patients were evaluated pre PCI then 1 month and 3 months post PCI for evaluation of mechanical dyssynchrony using tissue synchronization image (TSI).Results. Before revascularization mean left ventricular ejection fraction was 51.2±5.7 %, mean time to peak TSI was 213.6±10.9 ms; 1 month after PCI TSI improved significantly to 163.7±17.6 ms (p<0.001), 3 months after PCI showed more improvement to 120.7±26.9 ms (p<0.001). After 3m; 61 patients (40.7%) showed recovery to normal TSI value. The predictors of non-improvement of time to peak TSI after 3 months were diabetes mellitus (p=0.007), dyslipidemia (p=0.001) and stent length (p=0.001), number of stents (p=0.004). There were strong negative correlation between stent length and improvement of the time to peak TSI at 1 month (r=-0.352, p<0.001) and at 3 months (r=-0.509, p<0.001),and also with number of stent at 1 month (r= -0.173, p=0.034) and at 3 months (r=-0.499, p<0.001), but the correlation between stent diameter and improvement of the TSI wasn’t significant neither at 1 month nor at 3 months (r=0.055, p=0.504 and r= -0.018, p=0.827) respectively.Conclusion. Increased number and length of the implanted stents were predictors to non-improvement of mechanical dyssynchrony, while stent diameter didn’t affects the recovery.

The comparison of left ventricular mechanical dyssynchrony obtained by myocardial perfusion scintigraphy and gated blood pool SPECT to predict the result of the cardiac resynchronization therapy

Funding Acknowledgements Type of funding sources: None. Background/Introduction The assessment of left ventricular mechanical dyssynchrony (LV MD) is essential in identifying patients who may benefit from cardiac resynchronization therapy (CRT). Both gated myocardial perfusion scintigraphy (MPS) and gated blood pool SPECT (GBPS) are widely used to LV MD assessment [1,2]. Lack of data is available regarding the comparison of left ventricular MD parameters obtained by MPS and GBPS on cadmium-zinc-telluride (CZT) gamma-cameras and their prognostic value. Purpose to compare two scintigraphic methods – MPS and GBPS in LV MD assessment and to assess the capability of these methods to predict CRT response. Methods This study included 30 heart failure patients referred for CRT. Before CRT all patients underwent rest gated MPS and GBPS with LV MD evaluation on CZT cardiac gamma. Based on the phase analysis, the following indexes were estimated: phase standard deviation (SD) and phase histogram bandwidth (HBW). One year after CRT patients were divided to responders and non-responders. The response criteria were defined as LV end systolic volume decreased by ≥ 15% or LV ejection fraction increase by ≥ 5%, based on echocardiography. Results The correlation between gated MPI indexes and GBPS indexes was suboptimal: SD r = 0.39, p &lt; 0.05; HBW r = 0.48, p &lt; 0.05. Based on Mann-Whitney statistics significant differences between LV MD indexes, assessed by both MPS and GBPS were found: SD LV 56.1 (IQR 50.6 – 64) deg. vs 50.6 (37 - 61) deg., p &lt; 0.05 and HBW LV 188.64 (176 - 213) deg. vs 201.68 (180 - 240) deg., p = 0.03, respectively. The Bland-Altman analysis showed poor agreement between gated MPS and GBPS for SD assessment (p = 0.02) with mean difference value 7.02 (96% CI 1.11 to 12.9). However both MPS and GBPS were comparable in terms of HBW estimation (p = 0.18), with mean difference value of -12.5 (96% CI -31.5 to 6.3).MD indexes derived by MPS differed significantly between CRT responders and non-responders: SD 53.56 (47 – 63.4) deg. vs 62.4 (56-71) deg., p &lt; 0.05; HBW 182.1 (166 - 211) deg. vs 204.3 (179 - 225) deg., p &lt; 0.05. MD indexes obtained by GBPS did not show significant difference in CRT responders and non-responders: SD 51.2 (37 – 62) deg. vs 49.4 (40 – 58) deg., p = 0.92 and HBW 203.4 (186 - 237) deg. vs 198.5 (174 - 240) deg., p = 073. Univariate logistic regression analysis showed that SD and HBW assessed by gated MPS were independent predictors of CRT response: SD (OR = 0.91; 95% CI 0.85-0.97; p &lt; 0.05) and HBW (OR = 0.98; 95% CI 0.96-0.99; p =0.03). However MD indexes obtained by GBPS, did not show statistically significance in prediction of CRT response. Conclusion Gated MPS and GBPS are not interchangeable in terms of left ventricular MD assessment. Left ventricular SD and HBW obtained by gated MPI on CZT gamma-camera showed prognostic significance to predict CRT response.

Comparing Left Ventricular Mechanical Dyssynchrony between Diabetic and Non-Diabetic Patients with Normal Gated SPECT MPI

Introduction; the aim of this study was to employ phase analysis to diagnose left ventricular mechanical dyssynchrony (LVMD)in asymptomatic patients with diabetes mellitus type 2 and normal perfusion study to prevent diabetic cardiomyopathy.Methods & materials; Ninety-three consecutive patients with known type 2 diabetes and 81 age- and gender- matched patients without diabetes who were candidates for SPECT-MPI were considered as the control group. The presence of LVMD as an indicator of cardiomyopathy- was determined using phase analysis for each scan with quantitative gated SPECT (QGS) and corridor4DM (4DM) software. All outcomes such as phase bandwidth (PBW) and phase standard deviation (PSD) were compared between the two groups. Results; A total of 174 patients were included in the study. There were no statistically significant difference regarding demographic factors between the two groups (P>0.05). PBW showed statistically significant differences (increased in diabetics) between the control and diabetic patients (P < 0.05). Kruskal Wallis analysis revealed that as the duration of diabetes is prolonged, especially more than 15 years, the probability of LVMD is increased as well (p=0.021). Discussion; Fraction of asymptomatic diabetic patients with normal ejection fraction and gated SPECT MPI-especially those with prolonged diabetes- might have some degrees of LVMD. Phase analysis can detect this which in turn would prevent progress into heart failure.