Use of cyclic variation of integrated backscatter to assess contractile reserve and myocardial viability in chronic
Satoshi Yuda1, Jared Dart, Ofelia Najos
1University of Queensland, Department of Medicine, Brisbane, QLD, Australia.
Insights
Cyclic variation of integrated backscatter (CVIB) offers a non-subjective method for assessing myocardial viability. This resting echocardiography technique accurately detects contractile reserve and predicts heart muscle viability in patients with chronic left ventricular dysfunction.
Area of Science:
- Cardiology
- Echocardiography
- Myocardial Viability Assessment
Background:
- Stress echocardiography for myocardial viability is subjective and requires dobutamine.
- Accurate detection of viable myocardium is crucial for patient management.
- Chronic ischemic left ventricular dysfunction necessitates reliable viability assessment.
Purpose of the Study:
- To evaluate cyclic variation of integrated backscatter (CVIB) from apical views as a resting study for detecting contractile reserve (CR).
- To assess CVIB's accuracy in predicting myocardial viability in patients with chronic ischemic left ventricular dysfunction.
- To compare CVIB's performance against conventional dobutamine echocardiography (DbE).
Main Methods:
- Investigated 27 patients with chronic ischemic left ventricular dysfunction.
- Assessed resting and low-dose dobutamine CVIB in segments with resting asynergy.
- Correlated CVIB measurements with dobutamine-induced contractile reserve and follow-up revascularization outcomes.
Main Results:
- CVIB was measurable in 98% of segments at rest and 95% during low-dose dobutamine.
- Segments with contractile reserve showed significantly higher resting and low-dose dobutamine CVIB (P < 0.001).
- Resting CVIB achieved 85% accuracy in predicting myocardial viability, outperforming conventional DbE (62%, P < 0.01).
Conclusions:
- Assessment of CVIB from apical views is a feasible and accurate resting tool for detecting contractile reserve.
- CVIB accurately predicts myocardial viability in chronic left ventricular dysfunction.
- CVIB offers a non-invasive, objective alternative to subjective stress echocardiography methods.
Abstract:
The detection of viable myocardium has important implications for management, but use of stress echocardiography to detect this is subjective and requires exposure to dobutamine. We investigated whether cyclic variation (CV) of integrated backscatter (IB) from the apical views could provide a resting study for detection of contractile reserve (CR) and prediction of myocardial viability in 27 patients with chronic ischemic left ventricular (LV) dysfunction. Repeat echocardiography was performed after 6.7 +/- 3.8 months of follow-up; 14 patients underwent revascularization and 13 were treated medically. Using a standardized dobutamine echocardiography (DbE) protocol, images from three apical views were acquired at 80-120 frames/sec at rest and during stress. CR was identified if improvement of wall motion was observed at low dose (5 or 10 microg/kg/min) DbE. Myocardial viability was characterized by improvement at follow-up echocardiography in patients with revascularization. CVIB at rest and low dose dobutamine were assessed in 194 segments with resting asynergy (severe hypokinesis or akinesis), of which 88 (45%) were in patients who underwent revascularization. Of these, CVIB could be measured in 190 (98%) segments at rest and 185 (95%) at low dose dobutamine. Sixty-two (33%) segments had CR during low dose DbE and 50 (57%) segments showed wall-motion recovery (myocardial viability) at follow-up echocardiography. Segments with CR had significantly higher CVIB at rest (P < 0.001) and low dose dobutamine (P = 0.005) than segments without CR. Using optimal thresholds of CVIB (> 8.2 dB) at rest, the accuracy of CVIB for detecting CR was 70%. Compared with nonviable segments, viable segments had significantly higher CVIB at rest (P < 0.001) and low dose dobutamine (P < 0.001). Using optimal thresholds of CVIB (> 5.3 dB) at rest, the accuracy of CVIB for detecting myocardial viability was 85%, which was higher than that in conventional DbE (62%, P < 0.01). Thus, assessment of CVIB from the apical views is a feasible and accurate tool for detecting CR and predicting myocardial viability in chronic LV dysfunction.
