Letters to the Editor
PPVs of 320-slice CTA for each artery were investigated (Fig.1A). PPVs varied from 0.53 to 0.95 in all coronary arteries. However, they were much higher in the main branches of coronary artery (0.87–0.95 for LAD1–3, 0.85–0.91 for RCA1–3 and 0.83–0.90 for LCX1–3) than the other small branches (0.53 for PDA, 0.57–0.65 for D1 ~2 and 0.60–0.71 for OM1 ~2). The outcomes of 320-slice coronary CTA with respective to multiple confounders were summarized in Table 1 and Fig. 1B. When compared to the cases with good-to-moderate image quality, wall calcification and atrial fibrillation, higher AUCs and kappa indexes (κ ≥ 0.8, indicating excellent agreement between CTA and ICA) were observed in cases with excellent image quality, non-calcification and normal sinus rhythm. Meanwhile, Pearson Chi-square test showed that more true cases and less false cases were observed in segments with excellent image quality, non-calcification and normal sinus rhythm, than those with excellent (p b 0.001) to good (p = 0.029) image quality, mild-moderate (p b 0.001) to heavy (p b 0.001) calcification, and atrial fibrillation (p = 0.036), respectively. With respect to different pretest likelihoods and diagnostic radiologists, similar AUCs and kappa indexes were observed in all groups, and no significant differences of the true-case frequency and false-case frequency were observed among all groups. As showed at Fig. 1B, PPVs decreased in the order of excellent–good– moderate image quality. Higher PPVs could be obtained in cases with non-calcification, mild-moderate calcification and normal sinus rhythm, when compared to those with heavy calcification and atrial fibrillation.
219
Similar PPVs were observed in cases with different pretest likelihoods and diagnostic radiologists. The present retrospective study was a large sample study indicating that PPVs of CTA varied a lot with respect to multiple confounders in clinical routine. Among all potential confounders, large vessel diameter, excellent image quality, non-heavy calcified plaques and normal sinus rhythm might contribute to get a higher PPV. References [1] Dewey M. Coronary CT, versus MR angiography: pro CT—the role of CT angiography. Radiology 2011;258:329–39. [2] Li S, Liu J, Luo Y, et al. Diagnostic accuracy of noninvasive coronary angiography with 320slice computed tomography in the clinical routine: Results from four-year clinical registry at a single center. Int J Cardiol 2013;168:5035–6. [3] de Graaf FR, Schuijf JD, van Velzen JE, et al. Diagnostic accuracy of 320-row multidetector computed tomography coronary angiography in the non-invasive evaluation of significant coronary artery disease. Eur Heart J 2010;31:1908–15. [4] Li S, Ni Q, Wu H, et al. Diagnostic accuracy of 320-slice computed tomography angiography for detection of coronary artery stenosis: Meta-analysis. Int J Cardiol 2013;168:2699–705. [5] Austen WG, Edwards JE, Frye RL, et al. A reporting system on patients evaluated for coronary artery disease. Report of the Ad Hoc Committee for Grading of Coronary Artery Disease, Council on Cardiovascular Surgery, American Heart Association. Circulation 1975;51:5–40. [6] Matt D, Scheffel H, Leschka S, et al. Dual-source CT coronary angiography: image quality, mean heart rate and heart rate variability. AJR 2007;189:567–73. [7] Achenbach S, Ropers D, Hoffmann U, et al. Assessment of coronary remodeling in stenotic and nonstenotic coronary atherosclerotic lesions by multidetector spiral computed tomography. J Am Coll Cardiol 2004;43:842–7.
http://dx.doi.org/10.1016/j.ijcard.2014.03.193 0167-5273/© 2014 Elsevier Ireland Ltd. All rights reserved.
Left atrial regional phasic strain, strain rate and velocity by speckle-tracking echocardiography: normal values and effects of aging in a large group of normal subjects — Our reply Roxana Cristina Rimbaş a,⁎, Dragoş Vinereanu a,b a b
University and Emergency Hospital, Bucharest, Romania University of Medicine and Pharmacy Carol Davila, Bucharest, Romania
a r t i c l e
i n f o
Article history: Received 10 March 2014 Accepted 1 April 2014 Available online 12 April 2014 Keywords: Left atrial function Speckle tracking echocardiography Phasic function
We have read with interest the paper by Sun et al. [1] recently published in International Journal of Cardiology, regarding the evaluation of left atrial (LA) phasic functions, by speckle-tracking echocardiography (STE), in a large group of normal subjects. This study reported the normal values of LA phasic functions, assessed by 2D STE, in the largest sample size. Global longitudinal LA strain (S) and strain rate (SR) parameters determined by STE were demonstrated to be feasible and reproducible indices for the evaluation of LA functions [2–4].
⁎ Corresponding author. Tel./fax: + 40 213180576. E-mail address: [email protected] (R.C. Rimbaş).
Sun et al. [1] described all components of LA function: the contractile, reservoir, and conduit phases during the cardiac cycle. However, the LA STE curves were obtained using R-wave from the electrocardiogram as a reference point, which enabled in their opinion the generation of first positive peak, second positive peak, corresponding to LA reservoir, contractile, and conduit function as a difference between the first and the second peak, respectively. The LA S/SR curves are opposite to LV strain. The atria and ventricles move in opposite directions during the cardiac cycle, so the atrial myocardium lengthens during ventricular systole (positive strain), while the ventricular myocardium shortens during ventricular systole (negative strain). The strain curve must closely follow LA physiology. During the phase of LA reservoir (corresponding to the LV isovolumic contraction, ejection, and isovolumic relaxation), LA strain increases, achieving the highest peak just before mitral valve opening. During the conduit phase LA strain decreases, and achieves a negative peak at the end of LA contraction. Subsequently, during the diastasis both the S/SR profiles are flat, demonstrating that no LA wall deformation occurs in the late phase of the conduit period [2,3,5,6]. In this way we believe that LA contraction, reservoir, and also conduit functions are not as Sun et al. noted in Fig. 1 of their manuscript. In agreement with other authors [2,4] we believe that the contraction is represented in the LA strain curves as a negative peak (GSA−), the
220
Letters to the Editor
Fig. 1. Comparison between R-wave and P-wave methods, for generation of atrial strain curves.Panel A. The reference point was placed at the P-wave, allowing measurement of the negative global strain at maximal atrial contraction (GSA−) (pump function), first positive global strain at aortic valve closure (GSA+) (conduit function), and also sum of GSA− and GSA + (SUMGSA) (reservoir function);Panel B. The reference point was placed at the R-wave, allowing measurement of the first positive global strain at aortic valve closure (GSA+), and late positive global strain (GSAL). There was no negative pump function with this method.
Letters to the Editor
221
Fig. 2. Comparison between R-wave and P-wave methods, for generation of atrial strain rate curves.Four-chamber view depicting the region of interest (left) created by the speckletracking software and the corresponding average left atrial longitudinal strain rate along the cardiac cycle (right). The reference point was placed at the onset of the P-wave (panel A) and at the R-wave (panel B), which allowed the measurement of GSRE, early negative diastolic global strain rate; GSRL, late diastolic strain rate; GSR +, positive global strain rate at the beginning of LV systole, in the similar way. There were no differences between methods regarding SR parameters.
222
Letters to the Editor
conduit function as second positive peak (GSA+), and the reservoir phase as the sum between the absolute values of the first and the second peak (SUMGSA) (Fig. 1). In contrast to the assessment of LV strain, in which the R-wave from the ECG is used as a reference point, we considered that the use of the Pwave as the reference point enables the peak negative global LA strain, which corresponds to LA contractile function. We suggest that using Pwave as a reference point for generation of the strain curves might estimate correctly all LA functions. Currently, different studies use different methodologies, based on different reference points from the ECG (R-wave or P-wave), which might generate different normal values [5–8]. Saraiva et al. [2], in a similar population, used the P-wave for the generation of the strain curves and found that peak positive strain (GSA+) was 21.4 ± 6.7%, total LA strain (SUMGSA) was 35.6 ± 7.9%, and peak negative strain (GSA−) was 14.2 ± 3.3%. Sun et al. [1], using the R-wave as a reference point, found completely different value for peak positive strain 46.8 ± 7.7. However, due to an upward translation of the strain curve, they found a positive strain in end diastole of 19.6 ± 4.2%, interpreted as atrial contraction, when LA theoretically has no deformation at all. Our opinion is that, because after LA contraction the length of the LA is smaller than before contraction, LA contraction strain has to have a negative value. The same principle must be applied in diastasis, in which we must find a LA deformation of zero/around zero. Taking into account atrial physiology, we can easily understand that, by using R-wave as a reference point, the authors practically ignore the active pump (negative peak), and create a higher strain in diastasis, inconsistent with real physiological LA changes. None of the SR parameters changed with the variation of the reference point (Fig. 2). This could be of a particular clinical interest, because SR parameters can be used alone to estimate all LA functions. Our experience showed that the R-wave method, by comparison with the P-wave method, significantly underestimates active LA function, http://dx.doi.org/10.1016/j.ijcard.2014.04.008 0167-5273/© 2014 Elsevier Ireland Ltd. All rights reserved.
whereas passive and reservoir functions were significantly overestimated [9]. We strongly believe that for a correct definition of all LA functions, the principles of strain have to be respected, in order to avoid confusions and inaccuracies. In conclusion, we believe that methodological standardization is essential to define normal LA deformation, and also introduce LA deformation analysis in the clinical investigational setting.
References [1] Sun JP, Yang Y, Guo R, et al. Left atrial regional phasic strain, strain rate and velocity by speckle-tracking echocardiography: normal values and effects of aging in a large group of normal subjects. Int J Cardiol 2013;168:3473–9. [2] Saraiva RM, Demirkol S, Buakhamsri A, et al. Left atrial strain measured by twodimensional speckle tracking represents a new tool to evaluate left atrial function. J Am Soc Echocardiogr 2010;23:172–80. [3] Vianna-Pinton R, Moreno CA, Baxter CM, Lee KS, Tsang TS, Appleton CP. Two-dimensional speckle-tracking echocardiography of the left atrium: feasibility and regional contraction and relaxation differences in normal subjects. J Am Soc Echocardiogr 2009;22:299–305. [4] Sirbu C, Herbots L, D’hooge J, et al. Feasibility of strain and strain rate imaging for the assessment of regional left atrial deformation: a study in normal subjects. Eur J Echocardiogr 2006;7:199–208. [5] Cameli M, Lisi M, Mondillo S, et al. Left atrial longitudinal strain by speckle tracking echocardiography correlates well with left ventricular filling pressures in patients with heart failure. Cardiovasc Ultrasound 2010;8:1–14. [6] Kim DG, Lee KJ, Lee S, et al. Feasibility of two-dimensional global longitudinal strain and strain rate imaging for the assessment of left atrial function: a study in subjects with a low probability of cardiovascular disease and normal exercise capacity. Echocardiography 2009;26:1179–87. [7] Cameli M, Caputo M, Mondillo S, et al. Feasibility and reference values of left atrial longitudinal strain imaging by two dimensional speckle tracking. Cardiovasc Ultrasound 2009;7:1–6. [8] Cameli M, Lisi M, Giacomin E, et al. Chronic mitral regurgitation: left atrial deformation analysis by two-dimensional speckle tracking echocardiography. Echocardiography 2011;28:327–34. [9] Rimbas RC, Mihaila S, Dulgheru RE, Vinereanu D. How to assess the best left atrial function by speckle tracking: recommendations for a standard method. Circulation 2012;124(21(S)):A17532.
PPVs of 320-slice CTA for each artery were investigated (Fig.1A). PPVs varied from 0.53 to 0.95 in all coronary arteries. However, they were much higher in the main branches of coronary artery (0.87–0.95 for LAD1–3, 0.85–0.91 for RCA1–3 and 0.83–0.90 for LCX1–3) than the other small branches (0.53 for PDA, 0.57–0.65 for D1 ~2 and 0.60–0.71 for OM1 ~2). The outcomes of 320-slice coronary CTA with respective to multiple confounders were summarized in Table 1 and Fig. 1B. When compared to the cases with good-to-moderate image quality, wall calcification and atrial fibrillation, higher AUCs and kappa indexes (κ ≥ 0.8, indicating excellent agreement between CTA and ICA) were observed in cases with excellent image quality, non-calcification and normal sinus rhythm. Meanwhile, Pearson Chi-square test showed that more true cases and less false cases were observed in segments with excellent image quality, non-calcification and normal sinus rhythm, than those with excellent (p b 0.001) to good (p = 0.029) image quality, mild-moderate (p b 0.001) to heavy (p b 0.001) calcification, and atrial fibrillation (p = 0.036), respectively. With respect to different pretest likelihoods and diagnostic radiologists, similar AUCs and kappa indexes were observed in all groups, and no significant differences of the true-case frequency and false-case frequency were observed among all groups. As showed at Fig. 1B, PPVs decreased in the order of excellent–good– moderate image quality. Higher PPVs could be obtained in cases with non-calcification, mild-moderate calcification and normal sinus rhythm, when compared to those with heavy calcification and atrial fibrillation.
219
Similar PPVs were observed in cases with different pretest likelihoods and diagnostic radiologists. The present retrospective study was a large sample study indicating that PPVs of CTA varied a lot with respect to multiple confounders in clinical routine. Among all potential confounders, large vessel diameter, excellent image quality, non-heavy calcified plaques and normal sinus rhythm might contribute to get a higher PPV. References [1] Dewey M. Coronary CT, versus MR angiography: pro CT—the role of CT angiography. Radiology 2011;258:329–39. [2] Li S, Liu J, Luo Y, et al. Diagnostic accuracy of noninvasive coronary angiography with 320slice computed tomography in the clinical routine: Results from four-year clinical registry at a single center. Int J Cardiol 2013;168:5035–6. [3] de Graaf FR, Schuijf JD, van Velzen JE, et al. Diagnostic accuracy of 320-row multidetector computed tomography coronary angiography in the non-invasive evaluation of significant coronary artery disease. Eur Heart J 2010;31:1908–15. [4] Li S, Ni Q, Wu H, et al. Diagnostic accuracy of 320-slice computed tomography angiography for detection of coronary artery stenosis: Meta-analysis. Int J Cardiol 2013;168:2699–705. [5] Austen WG, Edwards JE, Frye RL, et al. A reporting system on patients evaluated for coronary artery disease. Report of the Ad Hoc Committee for Grading of Coronary Artery Disease, Council on Cardiovascular Surgery, American Heart Association. Circulation 1975;51:5–40. [6] Matt D, Scheffel H, Leschka S, et al. Dual-source CT coronary angiography: image quality, mean heart rate and heart rate variability. AJR 2007;189:567–73. [7] Achenbach S, Ropers D, Hoffmann U, et al. Assessment of coronary remodeling in stenotic and nonstenotic coronary atherosclerotic lesions by multidetector spiral computed tomography. J Am Coll Cardiol 2004;43:842–7.
http://dx.doi.org/10.1016/j.ijcard.2014.03.193 0167-5273/© 2014 Elsevier Ireland Ltd. All rights reserved.
Left atrial regional phasic strain, strain rate and velocity by speckle-tracking echocardiography: normal values and effects of aging in a large group of normal subjects — Our reply Roxana Cristina Rimbaş a,⁎, Dragoş Vinereanu a,b a b
University and Emergency Hospital, Bucharest, Romania University of Medicine and Pharmacy Carol Davila, Bucharest, Romania
a r t i c l e
i n f o
Article history: Received 10 March 2014 Accepted 1 April 2014 Available online 12 April 2014 Keywords: Left atrial function Speckle tracking echocardiography Phasic function
We have read with interest the paper by Sun et al. [1] recently published in International Journal of Cardiology, regarding the evaluation of left atrial (LA) phasic functions, by speckle-tracking echocardiography (STE), in a large group of normal subjects. This study reported the normal values of LA phasic functions, assessed by 2D STE, in the largest sample size. Global longitudinal LA strain (S) and strain rate (SR) parameters determined by STE were demonstrated to be feasible and reproducible indices for the evaluation of LA functions [2–4].
⁎ Corresponding author. Tel./fax: + 40 213180576. E-mail address: [email protected] (R.C. Rimbaş).
Sun et al. [1] described all components of LA function: the contractile, reservoir, and conduit phases during the cardiac cycle. However, the LA STE curves were obtained using R-wave from the electrocardiogram as a reference point, which enabled in their opinion the generation of first positive peak, second positive peak, corresponding to LA reservoir, contractile, and conduit function as a difference between the first and the second peak, respectively. The LA S/SR curves are opposite to LV strain. The atria and ventricles move in opposite directions during the cardiac cycle, so the atrial myocardium lengthens during ventricular systole (positive strain), while the ventricular myocardium shortens during ventricular systole (negative strain). The strain curve must closely follow LA physiology. During the phase of LA reservoir (corresponding to the LV isovolumic contraction, ejection, and isovolumic relaxation), LA strain increases, achieving the highest peak just before mitral valve opening. During the conduit phase LA strain decreases, and achieves a negative peak at the end of LA contraction. Subsequently, during the diastasis both the S/SR profiles are flat, demonstrating that no LA wall deformation occurs in the late phase of the conduit period [2,3,5,6]. In this way we believe that LA contraction, reservoir, and also conduit functions are not as Sun et al. noted in Fig. 1 of their manuscript. In agreement with other authors [2,4] we believe that the contraction is represented in the LA strain curves as a negative peak (GSA−), the
220
Letters to the Editor
Fig. 1. Comparison between R-wave and P-wave methods, for generation of atrial strain curves.Panel A. The reference point was placed at the P-wave, allowing measurement of the negative global strain at maximal atrial contraction (GSA−) (pump function), first positive global strain at aortic valve closure (GSA+) (conduit function), and also sum of GSA− and GSA + (SUMGSA) (reservoir function);Panel B. The reference point was placed at the R-wave, allowing measurement of the first positive global strain at aortic valve closure (GSA+), and late positive global strain (GSAL). There was no negative pump function with this method.
Letters to the Editor
221
Fig. 2. Comparison between R-wave and P-wave methods, for generation of atrial strain rate curves.Four-chamber view depicting the region of interest (left) created by the speckletracking software and the corresponding average left atrial longitudinal strain rate along the cardiac cycle (right). The reference point was placed at the onset of the P-wave (panel A) and at the R-wave (panel B), which allowed the measurement of GSRE, early negative diastolic global strain rate; GSRL, late diastolic strain rate; GSR +, positive global strain rate at the beginning of LV systole, in the similar way. There were no differences between methods regarding SR parameters.
222
Letters to the Editor
conduit function as second positive peak (GSA+), and the reservoir phase as the sum between the absolute values of the first and the second peak (SUMGSA) (Fig. 1). In contrast to the assessment of LV strain, in which the R-wave from the ECG is used as a reference point, we considered that the use of the Pwave as the reference point enables the peak negative global LA strain, which corresponds to LA contractile function. We suggest that using Pwave as a reference point for generation of the strain curves might estimate correctly all LA functions. Currently, different studies use different methodologies, based on different reference points from the ECG (R-wave or P-wave), which might generate different normal values [5–8]. Saraiva et al. [2], in a similar population, used the P-wave for the generation of the strain curves and found that peak positive strain (GSA+) was 21.4 ± 6.7%, total LA strain (SUMGSA) was 35.6 ± 7.9%, and peak negative strain (GSA−) was 14.2 ± 3.3%. Sun et al. [1], using the R-wave as a reference point, found completely different value for peak positive strain 46.8 ± 7.7. However, due to an upward translation of the strain curve, they found a positive strain in end diastole of 19.6 ± 4.2%, interpreted as atrial contraction, when LA theoretically has no deformation at all. Our opinion is that, because after LA contraction the length of the LA is smaller than before contraction, LA contraction strain has to have a negative value. The same principle must be applied in diastasis, in which we must find a LA deformation of zero/around zero. Taking into account atrial physiology, we can easily understand that, by using R-wave as a reference point, the authors practically ignore the active pump (negative peak), and create a higher strain in diastasis, inconsistent with real physiological LA changes. None of the SR parameters changed with the variation of the reference point (Fig. 2). This could be of a particular clinical interest, because SR parameters can be used alone to estimate all LA functions. Our experience showed that the R-wave method, by comparison with the P-wave method, significantly underestimates active LA function, http://dx.doi.org/10.1016/j.ijcard.2014.04.008 0167-5273/© 2014 Elsevier Ireland Ltd. All rights reserved.
whereas passive and reservoir functions were significantly overestimated [9]. We strongly believe that for a correct definition of all LA functions, the principles of strain have to be respected, in order to avoid confusions and inaccuracies. In conclusion, we believe that methodological standardization is essential to define normal LA deformation, and also introduce LA deformation analysis in the clinical investigational setting.
References [1] Sun JP, Yang Y, Guo R, et al. Left atrial regional phasic strain, strain rate and velocity by speckle-tracking echocardiography: normal values and effects of aging in a large group of normal subjects. Int J Cardiol 2013;168:3473–9. [2] Saraiva RM, Demirkol S, Buakhamsri A, et al. Left atrial strain measured by twodimensional speckle tracking represents a new tool to evaluate left atrial function. J Am Soc Echocardiogr 2010;23:172–80. [3] Vianna-Pinton R, Moreno CA, Baxter CM, Lee KS, Tsang TS, Appleton CP. Two-dimensional speckle-tracking echocardiography of the left atrium: feasibility and regional contraction and relaxation differences in normal subjects. J Am Soc Echocardiogr 2009;22:299–305. [4] Sirbu C, Herbots L, D’hooge J, et al. Feasibility of strain and strain rate imaging for the assessment of regional left atrial deformation: a study in normal subjects. Eur J Echocardiogr 2006;7:199–208. [5] Cameli M, Lisi M, Mondillo S, et al. Left atrial longitudinal strain by speckle tracking echocardiography correlates well with left ventricular filling pressures in patients with heart failure. Cardiovasc Ultrasound 2010;8:1–14. [6] Kim DG, Lee KJ, Lee S, et al. Feasibility of two-dimensional global longitudinal strain and strain rate imaging for the assessment of left atrial function: a study in subjects with a low probability of cardiovascular disease and normal exercise capacity. Echocardiography 2009;26:1179–87. [7] Cameli M, Caputo M, Mondillo S, et al. Feasibility and reference values of left atrial longitudinal strain imaging by two dimensional speckle tracking. Cardiovasc Ultrasound 2009;7:1–6. [8] Cameli M, Lisi M, Giacomin E, et al. Chronic mitral regurgitation: left atrial deformation analysis by two-dimensional speckle tracking echocardiography. Echocardiography 2011;28:327–34. [9] Rimbas RC, Mihaila S, Dulgheru RE, Vinereanu D. How to assess the best left atrial function by speckle tracking: recommendations for a standard method. Circulation 2012;124(21(S)):A17532.
