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Time to peak velocity of aortic flow is useful in predicting severe aortic stenosis
International Journal of Cardiology 172 (2014) e443–e446
Contents lists available at ScienceDirect
International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard
Letter to the Editor
Time to peak velocity of aortic flow is useful in predicting severe aortic stenosis Sung Hea Kim a, Je Sang Kim b, Bum Sung Kim c, Jinoh Choi c, Sang-Chol Lee c, Jae K. Oh c, Seung Woo Park c,⁎ a b c
Department of Internal Medicine, Konkuk University School of Medicine, Seoul, South Korea Department of Cardiothoracic Surgery, Sejong General Hospital, Sejong Heart Institute, Bucheon, South Korea Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
a r t i c l e
i n f o
Article history: Received 18 December 2013 Accepted 31 December 2013 Available online 22 January 2014 Keywords: Aortic stenosis Doppler ultrasound Echocardiography
Echocardiography has been the gold standard method to evaluate the severity of aortic valvular stenosis (AS) in clinical practice. The calculation of aortic valve area (AVA) by continuity equation is reliable and has been extensively studied in past publications [1–4]. To get the correct AVA by continuity equation, the following parameters must be reliably measured: 1) left ventricular (LV) outflow tract (LVOT) diameter (LVOTd); 2) pulsed wave Doppler signal of the blood flow in the LVOT; and 3) continuous wave Doppler signal of the blood flow at the stenotic aortic valve [5]. However, these measurements could not always be satisfactory. It is well known that moderate AS has fast up-stroke and slow down-stroke but severe AS has more slow up stroke [6,7] (Fig. 1). Therefore, the aim of this study was to determine whether simple time intervals such as time to peak velocity of the blood flow at aortic valve (Tvmax) and left ventricular ejection time (ET), Tvmax/ET, were related to the severity of AS in patients with preserved LV ejection fraction. We prospectively examined the echocardiograms of 87 AS patients between June 2010 and June 2011. The mean age was 74 years and 49 (56.3%) subjects were men. The patients who had a thickened aortic valve with AVA less than 2.0 cm 2 by continuity equation and with normal sinus rhythm were included. Exclusion
⁎ Corresponding author at: Cardiac & Vascular Center, Samsung Medical Center, Department of Medicine, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Kangnam-ku, Seoul, 135-710, South Korea. Tel.: +82 2 3410 3419; fax: +82 2 3410 3849. E-mail address: [email protected] (S.W. Park). 0167-5273/$ – see front matter © 2014 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijcard.2013.12.318
criteria were more than moderate amount of aortic regurgitation, more than moderate degree of mitral valve disease, serious ECG abnormalities such as atrial fibrillation, LBBB, paced rhythm, and left ventricular ejection fraction b50%. This study protocol was reviewed and approved by IRB. Peak and mean pressure gradients at aortic valve were measured, and aortic valvular area (AVA) was calculated by the continuity equation. We defined severe AS as AVA less than 1.0 cm2 and mild AS as more than 1.5 cm2 by continuity equation. In addition, Tvmax, which was defined as the time interval between the onset and the peak velocity of the aortic flow, and left ventricular ejection time (ET) with continuous Doppler technique (Fig. 1) were measured repeatedly with two weak interval by two independent observers without any information of AS severity. Data were expressed by mean value ± SD. One way ANOVA and post hoc analysis was performed to compare the parameters among groups. In correlating measured time variables and the AVA, mean pressure gradient (PG) was assessed with Pearson correlation. Linear correlation was used to examine inter-observer and intra-observer agreements. Receiver operating characteristic (ROC) curves were constructed to select the most advantageous cutoff points. Characteristics of each group are shown in Table 1. In One way ANOVA analysis, various parameters including mean PG, Tvmax, ET, LV wall thickness, ratio of early diastolic mitral inflow velocity (E) to early diastolic septal annular velocity (e′), i.e. E/e′, left atrial volume index (LAVI) and Tvmax/LVET show significant difference among groups. But after post hoc tests, only mean PG, Vmax, Tvmax and Tvmax/ET show significant difference among them (Fig. 2). Tvmax and Tvmax/ET became longer with the progression of AS. Tvmax correlated positively with mean PG (r = 0.685; p b 0.001), and negatively with AVA (r = − 0.679; p b 0.001). But LVET correlated very weakly with AVA and mean PG (r = − 0.130, 0.249 respectively). Other than the parameters Tvmax/ET, Tvmax divided by the cardiac cycle length for the correction of the cardiac cycle length variation (Tvmax/RR) also showed significant correlation with AVA or mean PG. But none of those parameters showed better correlation than Tvmax itself (Table 2, Fig. 3). In predicting severe AS, ROC curves were constructed for each of those variable (Fig. 4), where Tvmax (area under ROC curve; 0.928) is comparable to mean PG or Vmax (AUC; 0.957, 0.946 respectively) to predict severe AS. Tvmax was also a good predictor for 1.5 cm2 (AUC; 0.857). From ROC curves, the most optimal cutoff values of Tvmax were determined. A Tvmax of ≥ 106 ms was 76.9% sensitive and 90% specific for AVA b 1.0 cm2 (Table 3). Intra-observer
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S.H. Kim et al. / International Journal of Cardiology 172 (2014) e443–e446
Ejection Time
Ejection Time
Tvmax
Tvmax
Severe
Moderate
Fig. 1. Comparison of Doppler shapes between moderate and severe AS. Tvmax is longer in severe AS.
and inter-observer correlations (R2) for measuring Tvmax were 0.781 and 0.799 respectively. In the current study, time interval variables of the aortic valve were evaluated in pure AS patients with normal LVEF and sinus rhythm. Time related variables such as Tvmax and Tvmax/ET showed a good correlation with either AVA or mean PG. Moreover Tvmax had relatively good sensitivity and specificity in predicting severe AS in patients with normal LV systolic function. Therefore, it suggests that a simple time related parameter on echocardiographic study could accurately identify the patients with severe AS.
It is not a surprise that Tvmax was effective in predicting severe AS, because concepts of time intervals for AS severity were introduced before the emergence of the two dimensional echocardiography or Doppler technique. In the absence of echocardiography, ejection time index, time of the peak of systolic murmur, and time to one-half carotid upstroke were measured by physical examination, carotid pulse recording or phonocardiography [8–10]. It was known that prolonged time intervals might be related to the severity of AS. Javier et al. suggested that the waveform shape may provide an alternative guide to the grade of stenosis. They showed that slow late systolic opening of the stenotic aortic valve was associated with worse
Table 1 Characteristics of study subjects.
Tvmax (ms) ET (ms) Vmax (m/s) Mean PG (mm Hg) AVA (cm2) LVEDD (mm) LVESD (mm) IVS (mm) LVPW (mm) EF (%) Heart rate (beats/min) E wave (m/s) A wave (m/s) E/A ratio e′ (cm/s) E/e′ DT (ms) LAVI (cm3/m2) Tvmax/ET Age (yr) BSA (m2)
Mild (N = 31)
Moderate (N = 26)
Severe (N = 30)
Total (N = 87)
83.7 ± 17.4 296 ± 31.9 2.52 ± 0.33 13.6 ± 2.96 1.57 ± 0.19 50.6 ± 4.97 28.5 ± 4.03 9.91 ± 1.73 9.83 ± 1.56 72.0 ± 8.19 67.3 ± 9.66 0.69 ± 0.233 0.943 ± 0.234 0.760 ± 0.197 0.0617 ± 0.0169 11.8 ± 4.94 252 ± 69.2 30.1 ± 9.88 0.284 ± 0.057 74.8 ± 9.54 1.69 ± 0.186
100 ± 13.8 289 ± 61.5 3.71 ± 0.63 32.3 ± 11.2 1.13 ± .0.21 50.8 ± 4.66 29.6 ± 3.84 10.8 ± 2.01 10.6 ± 1.76 72.0 ± 7.48 63.9 ± 9.21 0.701 ± 0.190 0.902 ± 0.176 0.822 ± 0.409 0.0559 ± .0206 13.9 ± 5.29 258 ± 89.5 33.0 ± 13.3 0.338 ± 0.044 72.8 ± 11.4 1.64 ± 0.198
118.2 ± 17.5 318 ± 32.7 4.79 ± 0.56 54.1 ± 12.3 1.76 ± 0.0.18 53.5 ± 5.63 32.2 ± 4.58 12.3 ± 1.84 12.2 ± 1.48 68.6 ± 9.24 65.9 ± 13.1 0.798 ± 0.313 0.862 ± 0.229 0.985 ± 0.562 0.0504 ± .0165 16.2 ± 6.25 271 ± 71.3 38.9 ± 14.1 0.376 ± 0.039 74.2 ± 9.58 1.70 ± 0.247
99.8 ± 21.7 302 ± 44.2 3.66 ± 1.09 32.9 ± 19.6 1.16 ± 0.39 51.0 ± 5.13 29.5 ± 4.33 10.7 ± 2.04 10.5 ± 1.84 70.9 ± 8.46 66.2 ± 10.0 0.714 ± 0.244 0.917 ± 0.221 0.820 ± 0.359 0.0580 ± 0.0182 13.2 ± 5.53 257 ± 74.7 32.7 ± 12.2 0.334 ± 0.060 74.0 ± 10.3 1.68 ± 0.202
Tvmax; time to peak velocity, ET; left ventricular ejection time, Vmax; maximal velocity of aortic flow, PG; pressure gradient, AVA; aortic valve area, LVEDD; LV end diastolic dimension, LVESD; LV end systolic dimension, IVS: interventricular septum, LVPW; LV posterior wall, EF; ejection fraction, E wave and A wave; peak velocity of early filing and during atrial contraction respectively, e′; peak velocity of mitral annulus during early filling, DT; deceleration time, LAVI; left atrial volume index, BSA; body surface area.
S.H. Kim et al. / International Journal of Cardiology 172 (2014) e443–e446
Mild
Mild
Moderate
Severe
Moderate
Mild
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Moderate
Severe
Severe
Fig. 2. Distribution of time interval variables according to the severity of AS. Tvmax and Tvmax/ET show significant increase with the increase of AS severity but ejection time shows weak difference among groups.
Table 2 Correlations between variable parameters with AVA.
AVA Mean PG
Mean PG
ET
Vmax
Tvmax
EF
Tvmax/RR
ET/RR
Tvmax/ET
−0.868⁎ 1.00⁎
−0.130 0.249⁎
−0.887⁎ 0.968⁎
−0.679⁎ 0.685⁎
0.267⁎ −0.246
−0.632⁎ 0.577⁎
−0.244 0.166
−0.242⁎ 0.135
PG; pressure gradient, ET; left ventricular ejection time, Vmax; maximal velocity of aortic flow, Tvmax; time to peak velocity, EF; ejection fraction, RR; AVA; aortic valve area, RR: cardiac cycle length. ⁎ p value b 0.05.
long term outcome than rapid early systolic opening. It means that the time to peak velocity increased with AS severity [6]. It supports the findings that the time to peak velocity or corrected time to peak velocity could predict severe AS in the current study. The most important point of time interval parameters at aortic valve in terms of clinical practice is their simplicity and angle independent property. They might be measured easily and reliably where other
parameters such as Vmax, mean PG, or VTI could not be measured correctly due to the directional difference between blood flow and Doppler beam. Therefore, time interval parameters may give complementary information to the diagnosis of AS, especially Tvmax in the detection of severe AS although they could not replace the standard two dimensional or Doppler echocardiographic methods.
r=- 0.130 Mild
r=- 0.679
p=0.246
Moderate Severe
Ejection Time
Tvmax(msec)
p<0.001
AVA (cm2)
AVA (cm2)
Fig. 3. Correlation of AVA with time interval variables. Tvmax is correlated negatively with AVA but ET shows weak correlation with AVA.
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AVA ≤ 1.5 cm2
Sensitivity
Sensitivity
AVA ≤ 1.0 cm2
1-Specificity
1-Specificity
AUC(Area Under the Curve) AVA ≤ 1.0 cm2
AVA ≤ 1.5 cm2
0.957
0.937
Vmax
0.946
0.951
Tvmax
0.928
0.857
ET
0.733
0.631
Mean PG
Fig. 4. ROC curve of each parameter for predicting moderate or severe AS.
Table 3 Sensitivity and specificity of variable parameters for predicting severe AS. Sensitivity
Specificity
AVA ≤1.0 cm2 Tvmax ≥99.5 ms Tvmax ≥104.5 ms Tvmax ≥106.0 ms
92.3% 80.8% 76.9%
78.0% 82.0% 90.0%
AVA ≤1.5 cm2 Tvmax ≥86.0 ms Tvmax ≥89.5 ms Tvmax ≥91.5 ms
83.9% 78.6% 78.6%
70.0% 80.0% 85.0%
PG; pressure gradient, Tvmax; time to peak velocity, EF; ejection fraction, ET; left ventricular ejection time, AVA; aortic valve area.
References [1] Richards KL, Cannon SR, Miller JF, Crawford MH. Calculation of aortic valve area by Doppler echocardiography: a direct application of the continuity equation. Circulation 1986;73:964–9.
[2] Oh JK, Taliercio CP, Holmes Jr DR, et al. Prediction of the severity of aortic stenosis by Doppler aortic valve area determination: prospective Doppler-catheterization correlation in 100 patients. J Am Coll Cardiol 1988;11:1227–34. [3] Otto CM, Nishimura RA, Davis KB, Kisslo KB, Bashore TM. Doppler echocardiographic findings in adults with severe symptomatic valvular aortic stenosis. Am J Cardiol 1991;68:1477–84. [4] Taylor R. Evolution of the continuity equation in the Doppler echocardiographic assessment of the severity of valvular aortic stenosis. J Am Soc Echocardiogr 1990;3:326–30. [5] Dumont Y, Arsenault M. An alternative to standard continuity equation for the calculation of aortic valve area by echocardiography. J Am Soc Echocardiogr 2003;16:1309–15. [6] Bermejo J, Antoranz JC, Garcia-Fernandez MA, Moreno MM, Delcan JL. Flow dynamics of stenotic aortic valves assessed by signal processing of Doppler spectrograms. Am J Cardiol 2000;85:611–7. [7] Chambers J, Rajani R, Hankins M, Cook R. The peak to mean pressure decrease ratio: a new method of assessing aortic stenosis. J Am Soc Echocardiogr 2005;18:674–8. [8] Come PC, Riley MF, Ferguson JF, Morgan JP, McKay RG. Prediction of severity of aortic stenosis: accuracy of multiple noninvasive parameters. Am J Med 1988;85:29–37. [9] Munt B, Legget ME, Kraft CD, Miyake-Hull CY, Fujioka M, Otto CM. Physical examination in valvular aortic stenosis: correlation with stenosis severity and prediction of clinical outcome. Am Heart J 1999;137:298–306. [10] Voelkel AG, Kendrick M, Pietro DA, et al. Noninvasive tests to evaluate the severity of aortic stenosis. Limitations and reliability. Chest 1980;77:155–60.
Contents lists available at ScienceDirect
International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard
Letter to the Editor
Time to peak velocity of aortic flow is useful in predicting severe aortic stenosis Sung Hea Kim a, Je Sang Kim b, Bum Sung Kim c, Jinoh Choi c, Sang-Chol Lee c, Jae K. Oh c, Seung Woo Park c,⁎ a b c
Department of Internal Medicine, Konkuk University School of Medicine, Seoul, South Korea Department of Cardiothoracic Surgery, Sejong General Hospital, Sejong Heart Institute, Bucheon, South Korea Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
a r t i c l e
i n f o
Article history: Received 18 December 2013 Accepted 31 December 2013 Available online 22 January 2014 Keywords: Aortic stenosis Doppler ultrasound Echocardiography
Echocardiography has been the gold standard method to evaluate the severity of aortic valvular stenosis (AS) in clinical practice. The calculation of aortic valve area (AVA) by continuity equation is reliable and has been extensively studied in past publications [1–4]. To get the correct AVA by continuity equation, the following parameters must be reliably measured: 1) left ventricular (LV) outflow tract (LVOT) diameter (LVOTd); 2) pulsed wave Doppler signal of the blood flow in the LVOT; and 3) continuous wave Doppler signal of the blood flow at the stenotic aortic valve [5]. However, these measurements could not always be satisfactory. It is well known that moderate AS has fast up-stroke and slow down-stroke but severe AS has more slow up stroke [6,7] (Fig. 1). Therefore, the aim of this study was to determine whether simple time intervals such as time to peak velocity of the blood flow at aortic valve (Tvmax) and left ventricular ejection time (ET), Tvmax/ET, were related to the severity of AS in patients with preserved LV ejection fraction. We prospectively examined the echocardiograms of 87 AS patients between June 2010 and June 2011. The mean age was 74 years and 49 (56.3%) subjects were men. The patients who had a thickened aortic valve with AVA less than 2.0 cm 2 by continuity equation and with normal sinus rhythm were included. Exclusion
⁎ Corresponding author at: Cardiac & Vascular Center, Samsung Medical Center, Department of Medicine, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Kangnam-ku, Seoul, 135-710, South Korea. Tel.: +82 2 3410 3419; fax: +82 2 3410 3849. E-mail address: [email protected] (S.W. Park). 0167-5273/$ – see front matter © 2014 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijcard.2013.12.318
criteria were more than moderate amount of aortic regurgitation, more than moderate degree of mitral valve disease, serious ECG abnormalities such as atrial fibrillation, LBBB, paced rhythm, and left ventricular ejection fraction b50%. This study protocol was reviewed and approved by IRB. Peak and mean pressure gradients at aortic valve were measured, and aortic valvular area (AVA) was calculated by the continuity equation. We defined severe AS as AVA less than 1.0 cm2 and mild AS as more than 1.5 cm2 by continuity equation. In addition, Tvmax, which was defined as the time interval between the onset and the peak velocity of the aortic flow, and left ventricular ejection time (ET) with continuous Doppler technique (Fig. 1) were measured repeatedly with two weak interval by two independent observers without any information of AS severity. Data were expressed by mean value ± SD. One way ANOVA and post hoc analysis was performed to compare the parameters among groups. In correlating measured time variables and the AVA, mean pressure gradient (PG) was assessed with Pearson correlation. Linear correlation was used to examine inter-observer and intra-observer agreements. Receiver operating characteristic (ROC) curves were constructed to select the most advantageous cutoff points. Characteristics of each group are shown in Table 1. In One way ANOVA analysis, various parameters including mean PG, Tvmax, ET, LV wall thickness, ratio of early diastolic mitral inflow velocity (E) to early diastolic septal annular velocity (e′), i.e. E/e′, left atrial volume index (LAVI) and Tvmax/LVET show significant difference among groups. But after post hoc tests, only mean PG, Vmax, Tvmax and Tvmax/ET show significant difference among them (Fig. 2). Tvmax and Tvmax/ET became longer with the progression of AS. Tvmax correlated positively with mean PG (r = 0.685; p b 0.001), and negatively with AVA (r = − 0.679; p b 0.001). But LVET correlated very weakly with AVA and mean PG (r = − 0.130, 0.249 respectively). Other than the parameters Tvmax/ET, Tvmax divided by the cardiac cycle length for the correction of the cardiac cycle length variation (Tvmax/RR) also showed significant correlation with AVA or mean PG. But none of those parameters showed better correlation than Tvmax itself (Table 2, Fig. 3). In predicting severe AS, ROC curves were constructed for each of those variable (Fig. 4), where Tvmax (area under ROC curve; 0.928) is comparable to mean PG or Vmax (AUC; 0.957, 0.946 respectively) to predict severe AS. Tvmax was also a good predictor for 1.5 cm2 (AUC; 0.857). From ROC curves, the most optimal cutoff values of Tvmax were determined. A Tvmax of ≥ 106 ms was 76.9% sensitive and 90% specific for AVA b 1.0 cm2 (Table 3). Intra-observer
e444
S.H. Kim et al. / International Journal of Cardiology 172 (2014) e443–e446
Ejection Time
Ejection Time
Tvmax
Tvmax
Severe
Moderate
Fig. 1. Comparison of Doppler shapes between moderate and severe AS. Tvmax is longer in severe AS.
and inter-observer correlations (R2) for measuring Tvmax were 0.781 and 0.799 respectively. In the current study, time interval variables of the aortic valve were evaluated in pure AS patients with normal LVEF and sinus rhythm. Time related variables such as Tvmax and Tvmax/ET showed a good correlation with either AVA or mean PG. Moreover Tvmax had relatively good sensitivity and specificity in predicting severe AS in patients with normal LV systolic function. Therefore, it suggests that a simple time related parameter on echocardiographic study could accurately identify the patients with severe AS.
It is not a surprise that Tvmax was effective in predicting severe AS, because concepts of time intervals for AS severity were introduced before the emergence of the two dimensional echocardiography or Doppler technique. In the absence of echocardiography, ejection time index, time of the peak of systolic murmur, and time to one-half carotid upstroke were measured by physical examination, carotid pulse recording or phonocardiography [8–10]. It was known that prolonged time intervals might be related to the severity of AS. Javier et al. suggested that the waveform shape may provide an alternative guide to the grade of stenosis. They showed that slow late systolic opening of the stenotic aortic valve was associated with worse
Table 1 Characteristics of study subjects.
Tvmax (ms) ET (ms) Vmax (m/s) Mean PG (mm Hg) AVA (cm2) LVEDD (mm) LVESD (mm) IVS (mm) LVPW (mm) EF (%) Heart rate (beats/min) E wave (m/s) A wave (m/s) E/A ratio e′ (cm/s) E/e′ DT (ms) LAVI (cm3/m2) Tvmax/ET Age (yr) BSA (m2)
Mild (N = 31)
Moderate (N = 26)
Severe (N = 30)
Total (N = 87)
83.7 ± 17.4 296 ± 31.9 2.52 ± 0.33 13.6 ± 2.96 1.57 ± 0.19 50.6 ± 4.97 28.5 ± 4.03 9.91 ± 1.73 9.83 ± 1.56 72.0 ± 8.19 67.3 ± 9.66 0.69 ± 0.233 0.943 ± 0.234 0.760 ± 0.197 0.0617 ± 0.0169 11.8 ± 4.94 252 ± 69.2 30.1 ± 9.88 0.284 ± 0.057 74.8 ± 9.54 1.69 ± 0.186
100 ± 13.8 289 ± 61.5 3.71 ± 0.63 32.3 ± 11.2 1.13 ± .0.21 50.8 ± 4.66 29.6 ± 3.84 10.8 ± 2.01 10.6 ± 1.76 72.0 ± 7.48 63.9 ± 9.21 0.701 ± 0.190 0.902 ± 0.176 0.822 ± 0.409 0.0559 ± .0206 13.9 ± 5.29 258 ± 89.5 33.0 ± 13.3 0.338 ± 0.044 72.8 ± 11.4 1.64 ± 0.198
118.2 ± 17.5 318 ± 32.7 4.79 ± 0.56 54.1 ± 12.3 1.76 ± 0.0.18 53.5 ± 5.63 32.2 ± 4.58 12.3 ± 1.84 12.2 ± 1.48 68.6 ± 9.24 65.9 ± 13.1 0.798 ± 0.313 0.862 ± 0.229 0.985 ± 0.562 0.0504 ± .0165 16.2 ± 6.25 271 ± 71.3 38.9 ± 14.1 0.376 ± 0.039 74.2 ± 9.58 1.70 ± 0.247
99.8 ± 21.7 302 ± 44.2 3.66 ± 1.09 32.9 ± 19.6 1.16 ± 0.39 51.0 ± 5.13 29.5 ± 4.33 10.7 ± 2.04 10.5 ± 1.84 70.9 ± 8.46 66.2 ± 10.0 0.714 ± 0.244 0.917 ± 0.221 0.820 ± 0.359 0.0580 ± 0.0182 13.2 ± 5.53 257 ± 74.7 32.7 ± 12.2 0.334 ± 0.060 74.0 ± 10.3 1.68 ± 0.202
Tvmax; time to peak velocity, ET; left ventricular ejection time, Vmax; maximal velocity of aortic flow, PG; pressure gradient, AVA; aortic valve area, LVEDD; LV end diastolic dimension, LVESD; LV end systolic dimension, IVS: interventricular septum, LVPW; LV posterior wall, EF; ejection fraction, E wave and A wave; peak velocity of early filing and during atrial contraction respectively, e′; peak velocity of mitral annulus during early filling, DT; deceleration time, LAVI; left atrial volume index, BSA; body surface area.
S.H. Kim et al. / International Journal of Cardiology 172 (2014) e443–e446
Mild
Mild
Moderate
Severe
Moderate
Mild
e445
Moderate
Severe
Severe
Fig. 2. Distribution of time interval variables according to the severity of AS. Tvmax and Tvmax/ET show significant increase with the increase of AS severity but ejection time shows weak difference among groups.
Table 2 Correlations between variable parameters with AVA.
AVA Mean PG
Mean PG
ET
Vmax
Tvmax
EF
Tvmax/RR
ET/RR
Tvmax/ET
−0.868⁎ 1.00⁎
−0.130 0.249⁎
−0.887⁎ 0.968⁎
−0.679⁎ 0.685⁎
0.267⁎ −0.246
−0.632⁎ 0.577⁎
−0.244 0.166
−0.242⁎ 0.135
PG; pressure gradient, ET; left ventricular ejection time, Vmax; maximal velocity of aortic flow, Tvmax; time to peak velocity, EF; ejection fraction, RR; AVA; aortic valve area, RR: cardiac cycle length. ⁎ p value b 0.05.
long term outcome than rapid early systolic opening. It means that the time to peak velocity increased with AS severity [6]. It supports the findings that the time to peak velocity or corrected time to peak velocity could predict severe AS in the current study. The most important point of time interval parameters at aortic valve in terms of clinical practice is their simplicity and angle independent property. They might be measured easily and reliably where other
parameters such as Vmax, mean PG, or VTI could not be measured correctly due to the directional difference between blood flow and Doppler beam. Therefore, time interval parameters may give complementary information to the diagnosis of AS, especially Tvmax in the detection of severe AS although they could not replace the standard two dimensional or Doppler echocardiographic methods.
r=- 0.130 Mild
r=- 0.679
p=0.246
Moderate Severe
Ejection Time
Tvmax(msec)
p<0.001
AVA (cm2)
AVA (cm2)
Fig. 3. Correlation of AVA with time interval variables. Tvmax is correlated negatively with AVA but ET shows weak correlation with AVA.
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AVA ≤ 1.5 cm2
Sensitivity
Sensitivity
AVA ≤ 1.0 cm2
1-Specificity
1-Specificity
AUC(Area Under the Curve) AVA ≤ 1.0 cm2
AVA ≤ 1.5 cm2
0.957
0.937
Vmax
0.946
0.951
Tvmax
0.928
0.857
ET
0.733
0.631
Mean PG
Fig. 4. ROC curve of each parameter for predicting moderate or severe AS.
Table 3 Sensitivity and specificity of variable parameters for predicting severe AS. Sensitivity
Specificity
AVA ≤1.0 cm2 Tvmax ≥99.5 ms Tvmax ≥104.5 ms Tvmax ≥106.0 ms
92.3% 80.8% 76.9%
78.0% 82.0% 90.0%
AVA ≤1.5 cm2 Tvmax ≥86.0 ms Tvmax ≥89.5 ms Tvmax ≥91.5 ms
83.9% 78.6% 78.6%
70.0% 80.0% 85.0%
PG; pressure gradient, Tvmax; time to peak velocity, EF; ejection fraction, ET; left ventricular ejection time, AVA; aortic valve area.
References [1] Richards KL, Cannon SR, Miller JF, Crawford MH. Calculation of aortic valve area by Doppler echocardiography: a direct application of the continuity equation. Circulation 1986;73:964–9.
[2] Oh JK, Taliercio CP, Holmes Jr DR, et al. Prediction of the severity of aortic stenosis by Doppler aortic valve area determination: prospective Doppler-catheterization correlation in 100 patients. J Am Coll Cardiol 1988;11:1227–34. [3] Otto CM, Nishimura RA, Davis KB, Kisslo KB, Bashore TM. Doppler echocardiographic findings in adults with severe symptomatic valvular aortic stenosis. Am J Cardiol 1991;68:1477–84. [4] Taylor R. Evolution of the continuity equation in the Doppler echocardiographic assessment of the severity of valvular aortic stenosis. J Am Soc Echocardiogr 1990;3:326–30. [5] Dumont Y, Arsenault M. An alternative to standard continuity equation for the calculation of aortic valve area by echocardiography. J Am Soc Echocardiogr 2003;16:1309–15. [6] Bermejo J, Antoranz JC, Garcia-Fernandez MA, Moreno MM, Delcan JL. Flow dynamics of stenotic aortic valves assessed by signal processing of Doppler spectrograms. Am J Cardiol 2000;85:611–7. [7] Chambers J, Rajani R, Hankins M, Cook R. The peak to mean pressure decrease ratio: a new method of assessing aortic stenosis. J Am Soc Echocardiogr 2005;18:674–8. [8] Come PC, Riley MF, Ferguson JF, Morgan JP, McKay RG. Prediction of severity of aortic stenosis: accuracy of multiple noninvasive parameters. Am J Med 1988;85:29–37. [9] Munt B, Legget ME, Kraft CD, Miyake-Hull CY, Fujioka M, Otto CM. Physical examination in valvular aortic stenosis: correlation with stenosis severity and prediction of clinical outcome. Am Heart J 1999;137:298–306. [10] Voelkel AG, Kendrick M, Pietro DA, et al. Noninvasive tests to evaluate the severity of aortic stenosis. Limitations and reliability. Chest 1980;77:155–60.