Prognostic value of left ventricular ventricular dyssynchrony in left bundle branch block patients

Funding Acknowledgements

Type of funding sources: None.

Background

Patients with left bundle branch block (LBBB) patterns on the electrocardiogram include a heterogeneous group of patients with different prognosis and some of them with or without left ventricular mechanical dyssynchrony (LVMD). LVMD obtained by gated technetium 99m single photon emission computed tomography (SPECT) imaging could be an early tool to detect myocardial damage, identifying a high risk group.

Purpose

The aim of this study was to assess the prognostic value of LVMD in LBBB patients.

Methods

Five hundred and eighty consecutive patients with LBBB were referred for gated SPECT from August 2011 to June 2019. Phase analysis parameters Standard deviation (SD) and histogram bandwidth (HB) were obtained in rest gated SPECT imaging. LVMD was defined as the upper limit of the highest normal for phase analysis results in our control patients mean values plus two standard deviations (SD ≥ 21° or HB ≥ 67°). Follow up was performed by telephone contact or medical history review. Hard endpoint was all-cause death. Event-free survival curves were obtained. Univariate and multivariate regression analysis were performed.

Results

LVMD was observed in 254 (44%) patients. Compared to non LVMD patients had: similar age (67.68 ± 11.01 vs. 67.2 ± 10.3 y; p NS), more male (75.2% vs 39.6%), more hypertension (75.2% vs. 66.8%), more diabetes (22.8% vs. 13%) and more smoking history (31.9% vs. 23.7%) all p <0.05. A total of 495 patients completed the follow up (mean 29.8 ± 25.8 months). Fourteen patients died (2.8%), 12 had LVMD. Fig 1 shows Kaplan-Meier curve of event-free survival in relation to LVMD. Variables associated with all-cause death in the univariate analysis were: Score Rest Summed ≥ 4 (p 0.02), LV ejection fraction ≤ 35% (p < 0.01), diabetes (p 0.03) and LVMD (p <0.01). The absence of LVMD was a predictor of the lower risk of all-cause death in the multivariate analysis (adjusted hazard ratio: 0.13, 95% confidence interval: 0.03- 0.56; p < 0.01).

Conclusion

In our population of patients with LBBB, the absence of LVMD assessed by gated SPECT imaging identifies patients with lower risk of hard adverse events.

Impact of early post-stress LV Dis-sinchrony assessed by TC99m GSPECT myocardial perfusion: ischemic patients vs. normal subjects

Purpose

We aimed to determine the value of early post-stress Tc99msestamibi gated SPECT imaging for detecting changes in the two phase analysis synchrony parameters: Histogram bandwidth (HB) and Standard deviation (SD) in ischemic patients compared to normal subjects.

Methods

We prospectively included normal subjects and consecutive patients who had a positive stress test (angina or ST deviation during stress test). Both groups followed the same GSPECT protocol: an early stress image (acquired at maximum 10 minutes after the tracer injection), a delayed stress image (after 45 min of tracer injection) and the rest image. Phase analysis indices HB and SD were compared from early stress/ rest images and delayed stress/rest images in both groups. We compared the change of SD and HB indices (stress minus rest) for early and delayed images. The ischemic group was divided into mild ischemia (SDS≤3), moderate ischemia (SDS>3 and<8), and severe ischemia (SDS≥8)

Results

Twenty nine normal subjects and 57 ischemic patients were included. Thirty per cent of the ischemic group had mild ischemia, 32% moderate ischemia and 37% severe ischemia. SD and HB values decreased in early and delayed-stress images compared to those of rest images in normal subjects (all p<0,05). In the ischemic group early-stress SD increased compared to rest SD (p<0,05) while delayed- stress SD did not change. Early-stress HB did not change in comparison to rest HB while delayed-stress HB decrease compared to rest HB.The figure shows the comparison of SD and HB between early-stress, delayed-stress and rest images in normal subjects and ischemic patients. The Table shows the comparison of the change of SD and HB indices (stress minus rest) for early and delay images.

Conclusion

LVMS indices obtained by phase analysis of Tc99sestamibi GSPECT imaging, HB and SD decrease significantly when derived from early and delayed stress images compared to rest images in normal subjects. A progressive significant increase in SD and HB values in delayed and early stress images was observed in this population what could be an expression of post-ischemic LV dis-synchrony. Larger amounts of ischemia are related to progressive higher changes in SD and HB from early and delayed stress images versus rest images.

Funding Acknowledgement

Type of funding source: None