Quantification of aortic valve calcification in contrast enhanced computer tomography

Introduction

Aortic valve calcification (AVC) is linked to higher gradients and worse prognosis in aortic valve stenosis. Current guidelines recommend calcium scoring of the aortic valve as additional factor for decision making in low-flow, low-gradient aortic stenosis. Calcium Scoring is performed by native computed tomography (CT). For planning of interventional valve replacement (TAVR) a second scan with contrast agent (CECT) is needed at the cost of additional radiation exposure and work up time. The aim of this study is to assess and validate an estimate conversion factor of aortic valve quantification by using CECT without native imaging.

Methods

The Agatston score was measured on native CT in 45 patients and used as a reference. In contrast enhanced CT, mean aortic attenuation values in Hounsfield units (HU) were determined by placement of a region of interest in the ascending aorta with a standard deviation of 4xHU for calcification threshold. AVC was segmented semi-automatically. A conversion formula was created by plotting of native Agatston score versus aortic valve calcification segmented on contrast enhanced CT and linear regression. Validation of calculated conversion formula was established by Intra-class coefficient (ICC) and Bland Altman analysis.

Results

The linear regression model yielded an Agatston score conversion formula of 691 + 1.83 × AVCCECT. Validation of the formula in a validation cohort (n=20) showed high agreement (r2=0.802, ICC 0.915 (CI 95%: 0.786–0.966) p<0.001, p=0.055).

Conclusion

Approximation by our calculated conversion factor from contrast enhanced CT has shown excellent reliability to determine aortic valve calcification. Further studies are needed to extend this finding to larger cohorts and diverse clinical environments.

Funding Acknowledgement

Type of funding sources: None.

Invasive exercise hemodynamics predict survival in patients with clinical heart failure irrespective of left ventricular systolic function

Funding Acknowledgements

Type of funding sources: None.

Introduction

When aiming to stratify heart failure patients for mortality risk, exercise stress testing has proven to be relevant in specific populations of heart failure patients, but is not universally applied. Analysis of left ventricular systolic function (LVEF) remains the cornerstone for stratifying heart failure patients for prognosis and clinical treatment. The aim of the present study is to investigate the prognostic capabilities of invasive exercise testing in a real-world cohort of suspected heart failure patients in whom non-cardiac causes of dyspnea were excluded.

Methods

We retrospectively analyzed survival of patients who underwent right heart catheterization at rest and during exercise between 2007 to 2017 for dyspnea and expected heart failure. Pulmonary capillary wedge pressure (PCWP) at rest and the PCWP response to exercise, expressed as the ratio of PCWP at peak exercise to workload normalized to body weight [PCWL (mmHg/W/kg)], were determined. Mortality data was deducted from the official German death registry.

Results

A total of 682 patients [aged 64.1 ± 12 years, 269 (39.2%) women] were included. Based on LVEF, 515 patients (76.4%) had sustained LVEF ≥50%, 71 patients (10.5%) had heart failure with mildly-impaired LVEF (40-49%) and 88 patients (13.1%) had heart failure with reduced LVEF (≤40%). Absolute LVEF was not associated with all-cause mortality (HR 0.995; 95% CI 0.99-1.00; p=0.231). While increases in PCWP at rest an PCWL during exercise were both associated with death, the discriminative properties of pressure measurements derived during exercise were superior in ROC-analysis (AUC 0.637 for PCWP and AUC 0.728 for PCWL, p<0.001) Exercise hemodynamics and systolic function were next used to re-classify patients in four groups based on normal vs. impaired LVEF (≥/< 50%) and response to exercise (PCWL≥/<25.5 mmHg/W/kg for normal LVEF and PCWL≥/<34.7 mmHg/W/kg for impaired LVEF). In multivariate models adjusted for pertinent baseline parameters, patients with pathological response to exercise carried a 2.0-fold (with sustained LVEF, 95% CI 1.17-3.52, p=0.011) to 3.2-fold (with impaired LVEF, 95% CI 1.83-5.91, p<0.001) increased risk for death. Patients with impaired LVEF but featuring a normal response to exercise did not carry an increased risk for death (HR 1.117, 95% CI 0.453-2.757, p=0.810).

Discussion: In patients with clinical heart failure, invasive exercise testing improves the prediction of mortality. Subjects with a normal response to exercise have a relatively low mortality irrespective of systolic function.

Flow rate and stroke volume index as predictors of mortality in patients undergoing transcatheter aortic valve implantation

Background

Reduced flow rate and stroke volume are a common finding in patients with severe aortic stenosis. The aim of this study was to assess their impact on mortality in patients undergoing transcatheter aortic valve implantation (TAVI).

Methods

A total of 1080 patients with severe aortic stenosis who underwent TAVI between 2007 and 2017 were followed for a mean of 2.4±1.6 years. Patients were allocated into two groups according to flow rate (cut-off 200mL/s), 805 patients had a normal flow rate and 275 patients had reduced flow rate. Long-term survival was summarized using Kaplan-Meier curves and Cox-regression models.

Results

Patients with reduced flow rate were older (83.8±5.5 years; P<0.01) with more diabetics (36.7% P=0.02). Kaplan-Meier survival curves demonstrated inferior survival for patients with reduced flow rate (global log rank, P<0.01), Multivariable Cox-regression analysis (adjusted for age, creatinine, diabetes, hemoglobin and presence of atrial fibrillation) confirmed flow rate as an independent risk factor of all-cause mortality (HR: 0.998; 95%-CI: 0.997–0.999; P<0.01). Similar results were obtained for stroke volume index (SVI).

Conclusion

Patients with a reduced flow rate exhibit an increased mortality even after TAVI (similar to patients with reduced SVI) and should therefore be carefully evaluated in the heart-team.

PostTAVI survival according to flow rate

Funding Acknowledgement

Type of funding source: None

Invasive exercise hemodynamics in patients with severe primary mitral regurgitation and preserved ejection fraction predicts future valve surgery

Background

The role of invasive exercise hemodynamics in the management of asymptomatic patients with severe primary mitral regurgitation (MR) is unclear.

Methods and results

We compared the predictive power of parameters of invasive exercise testing for future valve surgery to guideline-defined non-invasive criteria. Maximal pulmonary capillary wedge pressure (PCWP), PCWP normalized to workload and weight (PCWL), and invasive maximal systolic pulmonary artery pressure (SPAP) were assessed in 113 asymptomatic patients with severe primary MR between 1996 and 2012. Mean age was 52±11 years, 16% were female, ejection fraction was ≥55% in all patients. During a median follow up of 4.5 years (IQR2.0; 8.3) 54 patients (48%) underwent valve surgery. In univariate analysis PCWP (P<0.001), PCWL (P<0.001), and maximal SPAP (P=0.009) were significantly associated with future mitral valve surgery. In multivariate analysis maximum PCWP and PCWL predicted future mitral valve surgery (HR 2.1 (1.44–3.10), P=0.005 and HR 1.31 (1.14–1.52), P<0.001, respectively) whereas SPAP did not. Adding maximum PCWP >25mmHg to a Cox regression model based on non-invasive guideline criteria resulted in a significant increase in the area under the curve (0.61 to 0.68, P=0.02).

Conclusion

In asymptomatic patients with severe primary mitral regurgitation and preserved left ventricular function invasive exercise hemodynamics improves information derived from current non-invasive guideline criteria.

Figure 1

Funding Acknowledgement

Type of funding source: None

Accuracy of biplane analysis of left ventricular ejection fraction based on two consecutive single plane studies

BACKGROUND AND PURPOSE

Mainly due to the high costs of biplane equipment many cardiac laboratories run single plane angiographic equipment only. Consequently, a biplane ventriculogram may only be done with two consecutive single plane studies. The aim of this investigation was to assess the accuracy of a biplane analysis of two consecutive single plane studies.

METHODS

A total of 42 patients (62 +/- 10 years, 76% males), able to tolerate two consecutive ventriculograms without arrhythmia during the first study underwent two consecutive biplane studies (LAO 60, RA0 30), using 40 ml of contrast each. After the first injection, the x-ray tube was moved in a neutral position, and then was replaced in the 30 RAO/60 LAO position. Digital data was analyzed by two separate investigators using commercially available software.

RESULTS

Intra-observer variability of left ventricular ejection fraction (LVEF) showed a high degree of agreement (single plane 1 vs. 2: r = 0.98; standard error of regression (Sy.x.): 2.8); the variability was slightly higher with two investigators (single plane: r = 0.92, Sy.x: 5.5 ) and with biplane analysis (biplane 1 vs. 2: r = 0.90, Sy. x: 5.7). End-diastolic volume index (EDVI) increased significantly from the first to the second study (84 +/- 28 ml/m2 vs 87 +/- 30 ml/m2; p = 0.017): Still LVEF of the two consecutive biplane studies showed very good agreement (biplane 1 vs. 2: mean difference (MD), -1.0; standard deviation of the difference (SDD), 5.2%). This agreement was almost as good as the one of LVEF values calculated from two consecutive single plane, but biplane analyzed studies compared to simultaneous biplane studies (MD, -0.5; SDD, 4.3%).

CONCLUSION

Despite the significant increase in EDVI after contrast injection, LVEF values determined from two consecutive studies remained virtually unchanged. Biplane analysis of LVEF values based on consecutive single plane studies resulted in similar and reliable values as determined by two consecutive biplane studies.

Regional wall motion assessment in stress echocardiography by tissue Doppler bull's-eyes

Quantification of regional myocardial wall velocities is needed in stress echocardiography for transition from subjective to quantitative assessment. Tissue Doppler allows quantitation of wall velocities, but interpretation is difficult and angle-dependent. Calculating the ratios of velocities with similar angles to the beam may overcome angle dependency. We measured left ventricular wall velocities during stress echocardiography with tissue Doppler. Regional peak systolic and early (E) and late (A) diastolic velocities were constructed in a "bull's-eye" format. Regional stress/rest and E/A ratios were calculated. Bull's-eye map construction demanded only minimal manual interaction, and the maps showed the left ventricular velocity distribution, simplifying wall motion reading markedly. Still, apical velocities appeared lower as a result of Doppler angle-dependency. With velocity ratios, angle-dependency was no longer noted. In stress echocardiography, wall motion abnormalities at rest and contractility changes with dobutamine became readily apparent. Bull's-eye display of quantitative tissue Doppler velocity allows rapid assessment of regional wall motion. Calculating the ratio of regional velocities circumvents the angle-dependency of Doppler. This novel technique has the potential for simplified and automated quantitative analysis in stress echocardiography.

Toxic-therapeutic ratio of sodium cyanate

Six patients with sickle cell anemia were treated with sodium cyanate (30 mg/kg/day). In four, treatment was stopped because of definite or suspected toxicity, and no improvement was seen in the other two. Most alarming was the sudden development of peripheral motor neuropathy in a patient whose red blood cells contained less than 0.6 mols NCO-/mol of hemoglobin: six months after treatment was stopped, function had not completely returned in this patient. Safe oral dosage regimens may not be effective, but extra-corporeal treatment of sickle cells with cyanate, or other compounds, might circumvent that problem.