Quantification of left ventricular indices from SSFP cine imaging: impact of real-world variability in analysis methodology and utility of geometric modeling.

PURPOSE: To assess the impact of "real-world" practice variation in the process of quantifying left ventricular (LV) mass, volume indices, and ejection fraction (EF) from steady-state free precession cardiovascular magnetic resonance (CMR) images. The utility of LV geometric modeling techniques was also assessed. MATERIALS AND METHODS: The effect of short-axis- versus long-axis-derived LV base identification, simplified versus detailed endocardial contouring, and visual versus automated identification of end-systole were evaluated using CMR images from 50 consecutive, prospectively recruited patients. Additionally, the performance of six geometric models was assessed. Repeated measurements were performed on 25 scans (50%) in order to assess observer variability. RESULTS: Simplified endocardial contouring significantly overestimated volumes and underestimated EF (-6 ± 4%, P < 0.0005) compared to detailed contouring. A mean difference of -34g (P < 0.0005) was observed between mass measurements made using short-axis- versus long-axis-derived LV base positioning. A technique involving long-axis LV base identification, signal threshold-based detailed endocardial contouring, and automated identification of end-systole had significantly higher observer agreement. Geometric models showed poor agreement with conventional analysis and high variability. CONCLUSION: Real-world variability in CMR image analysis leads to significant differences in LV mass, volume and EF measurements, and observer variability. Appropriate reference ranges should be applied. Use of geometric models should be discouraged.

High-concentration versus titrated oxygen therapy in ST-elevation myocardial infarction: a pilot randomized controlled trial.

BACKGROUND: The optimal approach to oxygen therapy in ST-elevation myocardial infarction (STEMI) is uncertain. METHODS: A randomized controlled trial was undertaken in which 136 patients presenting with their first STEMI uncomplicated by cardiogenic shock or marked hypoxia were randomized to receive high-concentration (6 L/min via medium concentration mask) or titrated oxygen (to achieve oxygen saturation 93%-96%) for 6 hours after presentation. The main outcome variables were 30-day mortality and infarct size assessed by troponin T level at 72 hours. Secondary outcomes included a meta-analysis of mortality data from this study and previous randomized controlled trials, and infarct size was assessed by magnetic resonance imaging at 4 to 6 weeks. RESULTS: There were 1 of 68 and 2 of 68 deaths in the high-concentration and titrated oxygen groups, respectively; a meta-analysis including these data with those from the 2 previous studies showed an odds ratio for mortality of high-concentration oxygen compared with room air or titrated oxygen of 2.2 (95% CI 0.8-6.0). There was no significant difference between high-concentration versus titrated oxygen in troponin T (ratio of mean levels 0.74, 95% CI 0.50-1.1, P = .14), infarct mass (mean difference -0.8 g, 95% CI -7.6 to 6.1, P = .82), or percent infarct mass (mean difference -0.6%, 95% CI -5.6 to 4.5, P = .83). CONCLUSION: This study found no evidence of benefit or harm from high-concentration compared with titrated oxygen in initially uncomplicated STEMI. However, our estimates have wide CIs, and as a result, large randomized controlled trials are required to resolve the clinical uncertainty.

Left ventricular filling and diastolic myocardial deformation in chronic primary mitral regurgitation.

AIMS: Chronic primary mitral regurgitation (MR) results in enhanced filling of the left ventricle (LV) during early diastole. Filling is impaired with the onset of LV systolic dysfunction, due to increased myocardial stiffness and reduced restoring forces. We investigated echocardiographic parameters of early diastolic function in relation to LV systolic function. METHODS AND RESULTS: Early diastolic transmitral flow and tissue Doppler velocities, propagation velocity of early filling (V(p)), and early diastolic strain rates (SR-E) were measured in 30 patients with chronic degenerative MR and 30 age-matched controls. MR subjects were further subdivided into group 1 (14 subjects) if they had well compensated LV, and group 2 (16 subjects) if they had one or more of the following: functional limitation (> NYHA class I), LV end-systolic diameter >or=4.0 cm, and LV ejection fraction

Comparison of real-time three-dimensional echocardiography with cardiovascular magnetic resonance for left ventricular volumetric assessment in unselected patients.

AIMS: To compare left ventricular (LV) volume indices and the ejection fraction (EF) obtained using real-time three-dimensional echocardiography (RT3DE) and cardiovascular magnetic resonance (CMR) in unselected patients representative of 'real-world' clinical practice, and to determine the effect of RT3DE image quality on these parameters. METHODS AND RESULTS: Sixty consecutive patients undergoing CMR underwent same day RT3DE. LV volume and EF measurements were made using both modalities and compared. All scans were independently analysed by a second observer to assess inter-observer variability, and 40% were re-analysed to assess intra-observer variability. RT3DE image quality was graded as good, adequate, and non-analysable. Thirteen (22%) patients had good RT3DE image quality, 29 (48%) had adequate image quality, and 18 (30%) had image quality precluding analysis. Body mass index and arrhythmia frequency were higher in patients with suboptimal image quality. RT3DE significantly underestimated end-diastolic volume (EDV) (-45 ± 35 mL, P < 0.001), end-systolic volume (ESV) (-11 ± 24 mL, P = 0.004), and EF (-7 ± 9%, P < 0.001) compared with CMR although the degree of underestimation was substantially less when image quality was good. Eleven patients (18%) classified as having a normal EF by CMR had a reduced EF according to RT3DE, all but one of which had suboptimal image quality. Observer variability for RT3DE was higher than for CMR for all parameters, however, the difference was not significant when RT3DE image quality was good. CONCLUSIONS: In contrast to previously published data from highly selected patient groups, 'real-world' RT3DE substantially underestimates LV volumes and EF. The degree of underestimation is related to image quality.