Measuring left ventricular mechanical dyssynchrony from ECG-gated SPECT myocardial perfusion imaging
J Chen1, E V Garcia, M M Henneman
1Department of Radiology, Emory University, Atlanta, GA 30322, USA. jchen22@emory.edu
Insights
Phase analysis of GSPECT MPI accurately measures left ventricular dyssynchrony, improving patient selection for cardiac resynchronization therapy (CRT) beyond traditional methods. This automated technique offers a repeatable and reproducible alternative to echocardiography for predicting CRT response.
Area of Science:
- Cardiology
- Medical Imaging
- Biomedical Engineering
Background:
- Cardiac resynchronization therapy (CRT) benefits severe heart failure patients.
- Traditional CRT selection criteria (NYHA class, LVEF, QRS duration) yield non-responders in over 30% of cases.
- Echocardiography-based LV dyssynchrony assessment has shown promise but faces limitations in real-world clinical practice.
Purpose of the Study:
- To introduce and review phase analysis, a novel technique for quantifying left ventricular (LV) dyssynchrony using ECG-gated SPECT MPI.
- To summarize the clinical validation and advantages of phase analysis compared to echocardiographic methods for assessing LV dyssynchrony.
Main Methods:
- Phase analysis utilizes Fourier harmonic functions on GSPECT MPI data to approximate regional wall thickening.
- It calculates regional onset of mechanical contraction (OMC) phases three-dimensionally to quantitatively assess LV dyssynchrony.
- The technique is automated, highly repeatable, and reproducible, requiring no additional procedures beyond standard GSPECT MPI.
Main Results:
- Phase analysis has demonstrated promising results in clinical validations when compared to tissue Doppler imaging (TDI).
- Its automated nature and high repeatability/reproducibility offer significant advantages over current echocardiographic techniques.
- The method can be integrated into existing GSPECT MPI workflows without extra patient procedures.
Conclusions:
- Phase analysis is a viable and advantageous tool for assessing LV dyssynchrony from GSPECT MPI.
- This technique has the potential to improve patient selection for CRT, thereby enhancing treatment efficacy.
- Further clinical adoption of phase analysis could optimize CRT outcomes in heart failure management.
Abstract:
Cardiac resynchronization therapy (CRT) has shown benefits in patients with severe heart failure. The traditional criteria to select patients for CRT (New York Heart Association [NYHA] class III or IV, depressed left ventricular [LV] ejection fraction, and prolonged QRS duration) result in at least 30% of the selected patients with no response to CRT. Recent studies with echocardiography have shown that the presence of LV dyssynchrony is an important predictor for response to CRT. However, the recent report from the predictors of response to cardiac resynchronization therapy (PROSPECT) trial suggested that under ''real-world'' conditions the current available echocardiographic techniques including tissue Doppler imaging (TDI) and myocardial strain-rate imaging are not ready for routine clinical practice to assess LV dyssynchrony. Phase analysis is a recently developed technique that allows measuring LV dyssynchrony from electrocardiogram (ECG)-gated single photon emission computed tomography (GSPECT) myocardial perfusion imaging (MPI). This technique uses Fourier harmonic functions to approximate regional wall thickening over the cardiac cycle and to calculate regional onset of mechanical contraction (OMC) phases. These OMC phases are obtained three-dimensionally over the entire left ventricle to quantitatively assess the degree of LV dyssynchrony. This technique has been compared to TDI and shown promising results in clinical validations. The advantages of this technique over echocardiography in measuring LV dyssynchrony are its automation, its high repeatability and reproducibility. It can be applied to any conventional GSPECT MPI study with no additional procedure. In this review the phase analysis methodology is described and its up-to-date clinical validations are summarized.
