Einar Hopp | Theragnostic Imaging

Scar imaging in the dyssynchronous left ventricle: Accuracy of myocardial metabolism by positron emission tomography and function by echocardiographic strain

Wed, 01 Feb 2023 00:00:00 +0000

Response to cardiac resynchronization therapy (CRT) is reduced in patients with high left ventricular (LV) scar burden, in particular when scar is located in the LV lateral wall or septum. Late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) can identity scar, but is not feasible in all patients. This study investigates if myocardial metabolism by ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) and contractile function by echocardiographic strain are alternatives to LGE-CMR. In a prospective multicenter study, 132 CRT candidates (91% with left bundle branch block) were studied by speckle tracking strain echocardiography, and 53 of these by FDG-PET. Regional myocardial FDG metabolism and peak systolic strain were compared to LGE-CMR as reference method. Reduced FDG metabolism (<70% relative) precisely identified transmural scars (≥50% of myocardial volume) in the LV lateral wall, with area under the curve (AUC) 0.96 (95% confidence interval (CI) 0.90-1.00). Reduced contractile function by strain identified transmural scars in the LV lateral wall with only moderate accuracy (AUC = 0.77, CI 0.71-0.84). However, absolute peak systolic strain >10% could rule out transmural scar with high sensitivity (80%) and high negative predictive value (96%). Neither FDG-PET nor strain identified septal scars (for both, AUC < 0.80). In CRT candidates, FDG-PET is an excellent alternative to LGE-CMR to identify scar in the LV lateral wall. Furthermore, preserved strain in the LV lateral wall has good accuracy to rule out transmural scar. None of the modalities can identify septal scar. The present study is part of the clinical study "Contractile Reserve in Dyssynchrony: A Novel Principle to Identify Candidates for Cardiac Resynchronization Therapy (CRID-CRT)", which was registered at clinicaltrials.gov (identifier NCT02525185).

Left ventricular regional glucose metabolism in combination with septal scar extent identifies CRT responders

Thu, 01 Jul 2021 00:00:00 +0000

Cardiac resynchronization therapy (CRT) is effective in selective heart failure (HF) patients, but non-response rate remains high. Positron emission tomography (PET) may provide a better insight into the pathophysiology of left ventricular (LV) remodeling; however, its role for evaluating and selecting patients for CRT remains uncertain. We investigated if regional LV glucose metabolism in combination with myocardial scar could predict response to CRT. Consecutive CRT-eligible HF patients underwent echocardiography, cardiac magnetic resonance (CMR), and ¹⁸F-fluorodeoxyglucose (FDG) PET within 1 week before CRT implantation. Echocardiography was additionally performed 12 months after CRT and end-systolic volume reduction ≥ 15% was defined as CRT response. Septal-to-lateral wall (SLR) FDG uptake ratio was calculated from static FDG images. Late gadolinium enhancement (LGE) CMR was analyzed semi-quantitatively to define scar extent. We evaluated 88 patients (67 ± 10 years, 72% males). ¹⁸F-FDG SLR showed a linear correlation with volumetric reverse remodeling 12 months after CRT (r = 0.41, p = 0.0001). In non-ischemic HF patients, low FDG SLR alone predicted CRT response with sensitivity and specificity of more than 80%; however, in ischemic HF patients, specificity decreased to 46%, suggesting that in this cohort low SLR can also be caused by the presence of a septal scar. In the multivariate logistic regression model, including low FDG SLR, presence and extent of the scar in each myocardial wall, and current CRT guideline parameters, only low FDG SLR and septal scar remained associated with CRT response. Their combination could predict CRT response with sensitivity, specificity, negative, and positive predictive value of 80%, 83%, 70%, and 90%, respectively. FDG SLR can be used as a predictor of CRT response and combined with septal scar extent, CRT responders can be distinguished from non-responders with high diagnostic accuracy. Further studies are needed to verify whether this imaging approach can prospectively be used to optimize patient selection.

Regional myocardial work by cardiac magnetic resonance and non-invasive left ventricular pressure: a feasibility study in left bundle branch block

Sat, 01 Feb 2020 00:00:00 +0000

Regional myocardial work may be assessed by pressure-strain analysis using a non-invasive estimate of left ventricular pressure (LVP). Strain by speckle tracking echocardiography (STE) is not always accessible due to poor image quality. This study investigated the estimation of regional myocardial work from strain by feature tracking (FT) cardiac magnetic resonance (CMR) and non-invasive LVP. Thirty-seven heart failure patients with reduced ejection fraction, left bundle branch block (LBBB), and no myocardial scar were compared to nine controls without LBBB. Circumferential strain was measured by FT-CMR in a mid-ventricular short-axis cine view, and longitudinal strain by STE. Segmental work was calculated by pressure-strain analysis. Twenty-five patients underwent 18F-fluorodeoxyglucose (FDG) positron emission tomography. Segmental values were reported as percentages of the segment with maximum myocardial FDG uptake. In LBBB patients, net CMR-derived work was 51 ± 537 (mean ± standard deviation) in septum vs. 1978 ± 1084 mmHg·% in the left ventricular (LV) lateral wall (P < 0.001). In controls, however, there was homogeneous work distribution with similar values in septum and the LV lateral wall (non-significant). Reproducibility was good. Segmental CMR-derived work correlated with segmental STE-derived work and with segmental FDG uptake (average r = 0.71 and 0.80, respectively). FT-CMR in combination with non-invasive LVP demonstrated markedly reduced work in septum compared to the LV lateral wall in patients with LBBB. Work distribution correlated with STE-derived work and energy demand as reflected in FDG uptake. These results suggest that FT-CMR in combination with non-invasive LVP is a relevant clinical tool to measure regional myocardial work.