الفهرس 
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Abstract
Cardiac resynchronization therapy (CRT) has emerged as an exciting treatment option for the subset of heart failure (HF) patients who remain symptomatic despite optimal medical management. However, using these conventional criteria for selection of patients for CRT, it was noted that 20–45% of patients did not respond to CRT. Echocardiographic techniques such as tissue Doppler imaging (TDI) and strain rate imaging have been used to identify mechanical dyssynchrony, but these methods lack reproducibility and have not consistently been able to discriminate between responders and non-responders to CRT.
Among myocardial imaging techniques, nuclear imaging has the unique advantages that it can assess myocardial perfusion, viability, and mechanical dyssynchrony and LV global function in a single scan.
The aim of the work was to explore the clinical value of quantitative gated SPECT in predicting response to cardiac resynchronization therapy (CRT).
This is a cross sectional prospective study that was carried out in the nuclear cardiology lab of Ain shams university hospital in the period from January 2016 to June 2018. It included 30 patients with advanced congestive heart failure eligible for CRT implantation. All patients were subjected to history taking and clinical examination, 12 lead rest-ECG, transthoracic echocardiography. All patients had resting gated SPECT MPI with phase analysis pre & post CRT implantation. The CRT was inserted blindly to the MPI results. Data were collected, verified, revised and edited, then statistically analyzed.
Patients were classified into two groups based on the EF improvement & NYHA class improvement after CRT implantation as follow:
- Responders group: (60% of total cohort) that showed improvement in EF ≥ 5% as well as an improvement one or more classes in the NYHA classification.
- Non-responders group: (40% of total cohort) that showed no improvement or an improvement < 5% in EF as well as no change in class in NYHA classification.
Patients with higher PSD & PHB, smaller EDV & ESV had significantly higher chance of becoming responders than patients with lower PSD & PHB & bigger EDV & ESV.
Patients with LV lead positioned at the latest activation segment & away from scared area had a significantly higher chance of becoming responders than patients with lead positioned away from the latest activation segment & in scared area.
Patients with smaller TPD had a significantly higher chance of becoming responders than patients with larger TPD.
Females, NICM, patients with LBBB & NYHA class III had significantly higher chance of becoming responders than male, ICM, patients with non-LBBB & NYHA class IV.
We found a PSD Cut-off value of 33º was associated with a sensitivity of 86.6% and a specificity 90% and a PHB cut-off value of 153º to have a sensitivity of 100% and a specificity 80% to be CRT responders.
This study concluded that the presence of a beneficial role for gated SPECT prior to CRT implantation for better patient selection using PSD & PHB cut-off points. Also it showed that placing the LV lead adjacent to the gated SPECT-derived latest activation segment and away from the scared area showed better CRT response.
As a result, we recommend that nuclear cardiology should have an auxiliary role, as a part of multi-modality imaging, in refining patient selection for CRT implantation and optimizing LV lead positioning. Also, large scale prospective multicenter studies to define the predictors of CRT responders using nuclear cardiology should be carried out.