Accuracy of three-dimensional versus two-dimensional echocardiography for quantification of aortic regurgitation and validation by three-dimensional three-directional velocity-encoded magnetic resonance imaging.

Quantitative assessment of aortic regurgitation (AR) remains challenging. The present study evaluated the accuracy of 2-dimensional (2D) and 3-dimensional (3D) transthoracic echocardiography (TTE) for AR quantification, using 3D 3-directional velocity-encoded magnetic resonance imaging (VE-MRI) as the reference method. Thirty-two AR patients were included. With color Doppler TTE, 2D effective regurgitant orifice area (EROA) was calculated using the proximal isovelocity surface area method. From the 3D TTE multiplanar reformation data, 3D-EROA was calculated by planimetry of the vena contracta. Regurgitant volumes (RVol) were obtained by multiplying the 2D-EROA and 3D-EROA by the velocity-time integral of AR jet and compared with that obtained using VE-MRI. For the entire population, 3D TTE RVol demonstrated a strong correlation and good agreement with VE-MRI RVol (r = 0.94 and -13.6 to 15.6 ml/beat, respectively), whereas 2D TTE RVol showed a modest correlation and large limits of agreement with VE-MRI (r = 0.70 and -22.2 to 32.8 ml/beat, respectively). Eccentric jets were noted in 16 patients (50%). In these patients, 3D TTE demonstrated an excellent correlation (r = 0.95) with VE-MRI, a small bias (0.1 ml/beat) and narrow limits of agreement (-18.7 to 18.8 ml/beat). Finally, the kappa agreement between 3D TTE and VE-MRI for grading of AR severity was good (k = 0.96), whereas the kappa agreement between 2D TTE and VE-MRI was suboptimal (k = 0.53). In conclusion, AR RVol quantification using 3D TTE is accurate, and its advantage over 2D TTE is particularly evident in patients with eccentric jets.

Non-invasive computed tomography coronary angiography as a gatekeeper for invasive coronary angiography.

To determine the rate of subsequent invasive coronary angiography (ICA) and revascularization in relation to computed tomography coronary angiography (CTA) results. In addition, independent determinants of subsequent ICA and revascularization were evaluated. CTA studies were performed using a 64-row (n = 413) or 320-row (n = 224) multidetector scanner. The presence and severity of CAD were determined on CTA. Following CTA, patients were followed up for 1 year for the occurrence of ICA and revascularization. A total of 637 patients (296 male, 56 ± 12 years) were enrolled and 578 CTA investigations were available for analysis. In patients with significant CAD on CTA, subsequent ICA rate was 76%. Among patients with non-significant CAD on CTA, subsequent ICA rate was 20% and among patients with normal CTA results, subsequent ICA rate was 5.7% (p < 0.001). Of patients with significant CAD on CTA, revascularization rate was 47%, as compared to a revascularization rate of 0.6% in patients with non-significant CAD on CTA and no revascularizations in patients with a normal CTA results (p < 0.001). Significant CAD on CTA and significant three-vessel or left main disease on CTA were identified as the strongest independent predictors of ICA and revascularization. CTA results are strong and independent determinants of subsequent ICA and revascularization. Consequently, CTA has the potential to serve as a gatekeeper for ICA to identify patients who are most likely to benefit from revascularization and exclude patients who can safely avoid ICA.

Quantitative assessment of mitral regurgitation: comparison between three-dimensional transesophageal echocardiography and magnetic resonance imaging.

BACKGROUND: quantification of mitral regurgitation severity with 2-dimensional (2D) imaging techniques remains challenging. The present study compared the accuracy of 2D transesophageal echocardiography (TEE) and 3-dimensional (3D) TEE for quantification of mitral regurgitation, using MRI as the reference method. METHODS AND RESULTS: two-dimensional and 3D TEE and cardiac MRI were performed in 30 patients with mitral regurgitation. Mitral effective regurgitant orifice area (EROA) and regurgitant volume (Rvol) were estimated with 2D and 3D TEE. With 3D TEE, EROA was calculated using planimetry of the color Doppler flow from en face views and Rvol was derived by multiplying the EROA by the velocity time integral of the regurgitant jet. Finally, using MRI, mitral Rvol was quantified by subtracting the aortic flow volume from left ventricular stroke volume. Compared with 3D TEE, 2D TEE underestimated the EROA by a mean of 0.13 cm(2). In addition, 2D TEE underestimated the Rvol by 21.6% when compared with 3D TEE and by 21.3% when compared with MRI. In contrast, 3D TEE underestimated the Rvol by only 1.2% when compared with MRI. Finally, one third of the patients in grade 1 and ≥50% of the patients in grade 2 and 3, as assessed with 2D TEE, would have been upgraded to a more severe grade, based on the 3D TEE and MRI measurements. CONCLUSIONS: quantification of mitral EROA and Rvol with 3D TEE is feasible and accurate as compared with MRI and results in less underestimation of the Rvol as compared with 2D TEE.

Diagnostic accuracy of 320-row multidetector computed tomography coronary angiography to noninvasively assess in-stent restenosis.

OBJECTIVES: Percutaneous coronary intervention with stent implantation is routinely performed to treat patients with obstructive coronary artery disease. However, thus far, noninvasive assessment of in-stent restenosis has been challenging. Recently, 320-row multidetector computed tomography coronary angiography (CTA) was introduced, allowing volumetric image acquisition of the heart in a single heart beat or gantry rotation. The aim of this study was to evaluate the diagnostic performance of 320-row CTA in the evaluation of significant in-stent restenosis. Invasive coronary angiography (ICA) served as the standard of reference, using a quantitative approach. MATERIALS AND METHODS: The population consisted of patients with previous coronary stent implantation who were clinically referred for cardiac evaluation because of recurrent chest pain and who underwent both CTA and ICA. CTA studies were performed using a 320-row CTA scanner with 320 detector-rows, each 0.5 mm wide, and a gantry rotation time of 350 milliseconds. Tube voltage and current were adapted to body mass index and thoracic anatomy. The entire heart was imaged in a single heart beat, with a maximum of 16-cm craniocaudal coverage. During the scan, the ECG was registered simultaneously for prospective triggering of the data. First, CTA stent image quality was assessed using a 3-point grading scale: (1) good image quality, (2) moderate image quality, and (3) poor image quality. Subsequently, the presence of in-stent restenosis was determined on a stent and patient basis by a blinded observer. Significant in-stent restenosis was defined as >or=50% luminal narrowing in the stent lumen or the presence of significant stent edge stenosis. Overlapping stents were considered to represent a single stent. Results were compared with ICA using quantitative coronary angiography. In addition, CTA stent image quality and diagnostic accuracy were related to stent characteristics and heart rate during CTA image acquisition. RESULTS: The population consisted of 53 patients (37 men, mean age: 65 +/- 13 years) with a total of 89 stents available for evaluation. ICA identified 12 stents (13%) with significant in-stent restenosis. A total of 7 stents (8%) were of nondiagnostic CTA stent image quality, and were considered positive. Sensitivity, specificity, positive, and negative predictive values were 92%, 83%, 46%, and 98%, respectively on a stent basis. Five CTA studies (9%) were of nondiagnostic quality for the evaluation of in-stent restenosis and were considered positive. Sensitivity, specificity, positive, and negative predictive values were 100%, 81%, 58%, and 100%, respectively on a patient level. Stent diameter <3 mm as well as stent strut thickness >or=140 mum were associated with decreased CTA stent image quality and diagnostic accuracy. Heart rate during CTA acquisition and stent overlap were not associated with image degradation. CONCLUSIONS: The present results show that 320-row CTA allows accurate noninvasive assessment of significant in-stent restenosis. However, stents with a large diameter and thin struts allowed better in-stent visualization than stents with a small diameter or thick struts. Consequently, noninvasive assessment of in-stent restenosis using CTA may be an attractive and feasible alternative particularly in carefully selected patients.

Evaluation of contraindications and efficacy of oral Beta blockade before computed tomographic coronary angiography.

Multidetector computed tomographic coronary angiography (CTA) image quality is inversely related to the heart rate (HR). As a result beta-blocking medication is routinely administered before investigation. In the present study, the use, contraindications, and efficacy of prescan beta blockade with regard to HR reduction and CTA image quality were assessed. In 537 patients referred for CTA, the baseline HR and blood pressure were measured on arrival, and contraindications for beta blockade were noted. Unless contraindicated, a single dose of metoprolol was administered orally 1 hour before data acquisition in patients with a HR of > or =65 beats/min according to a predefined medication protocol. After 1 hour, the HR was remeasured. A total of 283 patients (53%) had a HR of > or =65 beats/min. In this group, beta blockade was contraindicated in 46 patients (16%). Metoprolol was administered to the remaining 237 patients. However, 26 patients (11%) received suboptimal (lower dose than prescribed by protocol) beta blockade because of contraindications. Of the 211 patients receiving optimal beta blockade, 57 (27%) did not achieve the target HR. Of the patients with contraindications to beta blockade, 43 (60%) did not achieve the target HR. Compared to patients with optimal HR control, those receiving no or suboptimal beta blockade because of contraindications had significantly fewer examinations of good image quality (40% vs 74%, p <0.001), and significantly more examinations of poor image quality (20% vs 6%, p <0.001). In conclusion, most patients require HR reduction before CTA. Contraindications to beta blockade are present in a substantial proportion of patients. This results in suboptimal HR control and image quality, indicating the need for alternative approaches for HR reduction.

Myocardial contractile reserve predicts improvement in left ventricular function after cardiac resynchronization therapy.

BACKGROUND: Myocardial contractile reserve has been shown to provide important prognostic information in patients with heart failure. We hypothesized that myocardial contractile reserve would predict left ventricular (LV) reverse remodeling after cardiac resynchronization therapy (CRT). METHODS: Thirty-one consecutive patients with heart failure (LV ejection fraction [LVEF] 26% +/- 7%, 35% nonischemic cardiomyopathy) underwent echocardiography during low-dose dobutamine infusion before CRT implantation to assess global contractile reserve (improvement in LVEF) and local contractile reserve in the region of the LV pacing lead (assessed by radial strain using speckle tracking analysis). Responders were defined by a decrease in LV end-systolic volume > or = 15% after 6 months of CRT. RESULTS: During low-dose dobutamine infusion, responders showed a greater increase in LVEF compared with nonresponders (delta 13% +/- 8% vs 3% +/- 4%, P < .001). Furthermore, contractile reserve was directly related to improvement in LVEF after 6 months of CRT (r = 0.80, P < .001). Moreover, a cutoff value of > 7.5% increase in dobutamine-induced LVEF exhibited a sensitivity of 76% and a specificity of 86% to predict response after 6 months of CRT (area under the curve 0.87). Lastly, contractile reserve in the region in the LV pacing lead was present only in responders (delta strain during low-dose dobutamine 6% +/- 5% in responders vs -1% +/- 4% in nonresponders, P = .002). CONCLUSIONS: The current study demonstrates that myocardial contractile reserve (> 7.5% increase in LVEF during low-dose dobutamine infusion) predicts LV reverse remodeling after CRT.