Imaging and prognosis in mitral and pulmonary valve disease 857

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tients with Mitral Valve Prolapse (MVP). The aim of our study was to investi- gate the prevalence, echocardiographic and biochemical predictors, and possible.
International Journal of Cardiology 168 (2013) e151–e153

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International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard

Letter to the Editor

Effects of left atrial strain on functional capacity in chronic severe mitral regurgitation☆ Li-Tan Yang a, Jhih-Yuan Shih b, Yen-Wen Liu c, Yi-Heng Li c, Liang-Miin Tsai c, Chwan-Yau Luo d, Wei-Chuan Tsai c,⁎ a

Department of Internal Medicine, National Cheng Kung University Hospital Dou-Liou Branch, Yunlin, Taiwan Department of Internal Medicine, Chi-Mei Hospital, Tainan, Taiwan Department of Internal Medicine, National Cheng Kung University Hospital, Tainan, Taiwan d Department of Surgery, National Cheng Kung University Hospital, Tainan, Taiwan b c

a r t i c l e

i n f o

Article history: Received 31 July 2013 Accepted 19 August 2013 Available online 26 August 2013 Keywords: Mitral regurgitation Left atrium Strain Speckle tracking echocardiography

Mitral regurgitation (MR) is the most frequent valve disease in western countries and chronic severe primary MR is the leading cause for surgery [1]. The symptom of heart failure is not only a major surgical indication but also determines prognosis and surgical risk [2]. Chronic MR initiates cardiac remodeling in both the left atrium (LA) and left ventricle (LV). LV enlargement and dysfunction are well known poor prognostic factors. On the contrary, the role of LA remodeling, reflecting a direct target organ damage, has been little studied in chronic primary MR [3]. The function of LA includes the reservoir, conduit, and active contractile phases, which can be analyzed with a novel tool, the 2-dimensional speckle tracking echocardiography (STE) [4]. LA dysfunction represented by impaired LA deformation has been observed to be in association with severe MR [3]. We hypothesized that these changes play a role in the occurrence of heart failure symptoms in these patients. Totally, 136 consecutive patients with chronic severe primary MR due to intrinsic valvular disease and a preserved LV ejection fraction (LVEF) (≥55%) were screened. Severe MR was diagnosed according to the American Society of Echocardiography (ASE) criteria [5]. The exclusion criteria were [1] MR secondary to a dilated LV and LV dysfunction

☆ This study was supported by grant NSC 101-2314-B-006-074 from the National Science Council, Executive Yuan, Taipei, Taiwan. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose. ⁎ Corresponding author at: Department of Internal Medicine, National Cheng Kung University Hospital, 138 Sheng-Li Road Tainan 704, Taiwan. Tel.: +886 6 2353535 2388; fax: +886 6 2753834. E-mail address: [email protected] (W.-C. Tsai). 0167-5273/$ – see front matter © 2013 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijcard.2013.08.070

(functional MR) [2], ischemic MR [3], concomitant significant mitral stenosis, aortic regurgitation or stenosis [4], congenital heart disease [5], previous history of cardiac surgery for mitral valve, and [6] inadequate or incomplete echocardiography images. The remaining 110 patients (mean age 57 ± 16 years, 55% men) formed our study group. The New York Heart Association (NYHA) functional classification at the start of enrollment and the past histories were recorded via the medical records. Standard echocardiography was performed (Vivid 7, GE-Vingmed, Horten, Norway) with a 3.5-MHz multiphase array probe. Measurements and quantification, such as LA volume index (LAVi) and LA total emptying fraction (LATEF), were obtained based on ASE recommendations and previous studies [4,6]. The images were analyzed offline by computer software (EchoPAC PC 09, GE-Vingmed, Horten, Norway). The method for STE measurement of LV global longitudinal strain (GLS) as well as the LA deformation analysis, including peak positive LA strain (LASp), peak negative strain (LASn), peak positive filling strain rate (LASRf), peak negative conduit strain rate (LASRc), and peak negative atrial strain rate (LASRa), was well described in our previous studies [4,7]. Comparison between the three different NYHA functional classes was performed using Chi-square (χ2) test for categorical variables and one-way ANOVA test for continuous variables. Multiple logistic regression analysis was used to identify factors highly associated with severe heart failure symptoms and their possible mechanisms. There were 35 (32%) patients in NYHA I, 62 (56%) in NYHA II, and 13 (12%) in NYHA III. LASp (29.9 ± 8.9, 25.2 ± 10.1, 18.8 ± 6.4%; p = 0.002), LASRr (2.5 ± 0.5, 2.3 ± 0.7, 2.0 ± 0.8 s−1; p = 0.055), and LASRc (−2.4 ± 0.7, −2.1 ± 0.8, −1.7 ± 0.5 s−1, p = 0.015) as well as age, presence of atrial fibrillation (AF), LV mass index, and estimated pulmonary artery systolic pressure were relevant to stepwise decline in NYHA functional class (I to III) (Tables 1, 2). After multivariate logistic regression analysis controlling for age and status of AF, only a low LASp (OR 0.891, 95% CI 0.796–0.997, p = 0.044) independently related with the occurrence of more severe heart failure symptoms (NYHA III) (Table 2 and Fig. 1). Age (OR 1.081, 95% CI 1.033–1.132, p = 0.001) and diabetes mellitus (OR 10.379, 95% CI 1.008–106.83, p = 0.049) significantly correlated with a decreased LASp (lower than the medium level at 23.9%). Our current study demonstrated that among patients with chronic severe primary MR, LASp is distinctively related with a worse functional capacity (NYHA III). Being the direct target organ affected by MR, LA remodeling occurs early; nevertheless it receives little attention on the

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Table 1 Clinical characteristics of the study population.

Age (years) Male HR (beats/min) Hypertension Diabetes mellitus Atrial fibrillation Prevalent CAD Current smoker Hyperlipidemia

Total N = 110

NYHA I N = 35

NYHA II N = 62

NYHA III N = 13

p-Value

57.3 ± 16.5 60 (54.5%) 76.0 ± 17.3 73 (66) 12 (11) 12 (11) 7 (6) 12 (11) 43 (39)

50.2 ± 13.4 24 (68.6%) 72.1 ± 14.6 17 (49) 1(3) 0 (0) 1 (3) 4 (11) 12 (34)

59.7 ± 17.0 29 (46.8%) 74.5 ± 12.6 45 (73) 10(16) 8(13) 5 (8) 5 (8) 24 (39)

64.8 ± 6.1 7 (53.8%) 93.2 ± 30.4 11 (85) 1 (8) 4 (31) 1 (8) 3 (23) 7 (54)

0.004 0.117 0.347 0.019 0.122 0.007 0.442 0.298 0.341

HR = heart rate; NYHA = New York Heart Association functional classification; CAD = coronary artery disease. Data are expressed as mean ± SD or number (%).

contrary to the focus on LV remodeling. In our population, increased LAVi and decreased LATEF reflect the impact of MR; however the functional status was not affected by an enlarged LA. Decreased LA strain in chronic MR has been noted in previous studies with potential explanations [3]. LA becomes stiffer and less compliant after serial changes propelled by chronic MR, including structural remodeling, chronic inflammation, LA myocyte hypertrophy, interstitial fibrosis and decreased matrix metalloproteinase expression [8], which may affect LA energy storage during ventricular systole (the reservoir phase of LA) and result in impaired LV filling after the opening of the mitral valve [9]. Mechanisms for the decreased reservoir function of LA are currently unknown. We speculate that severe MR disturbs LA energy balance during LV systole, which possibly leads to impaired reservoir function (represented by a decreased LASp) and impaired LV filling. This consequence may contribute to the severity of heart failure symptoms in our population. Our study is the first to demonstrate the link between LASp and a stepwise decline in NYHA functional class. The prognostic impact of LA enlargement has been well addressed in many studies regarding symptom prediction, AF development, cardiac mortality, and post-operative mortality [8]. Our study shows a similar degree of LA enlargement in different functional classes. Hence, among chronic severe

Fig. 1. The correlation of LASp in the stepwise decline of NYHA functional class. The peak positive strain of the left atrium (LASp) decreased with respect to the severity of New York Heart Association (NYHA) functional classification (odds ratio for severe symptom 0.891, 95% confidence interval, 0.796–0.997, p = .044).

MR patients who already have an enlarged LA, LA deformation adds value in the reflection of clinical heart failure symptoms. The LV GLS and other parameters for LV remodeling (LVEF and size of LV) showed no relevance among functional classes, indicating that LASp can be used early before subtle LV dysfunction for heart failure symptom correlation. Another noteworthy finding is the link between impaired LASp with advanced age and diabetes mellitus, which carries 10 times the risk for a declined LASp. Plausible explanation is the acceleration of LA remodeling in diabetic patients, which leads to myocellular hypertrophy, fibrosis and a stiff and less compliant LA, reflected by impaired reservoir function [10]. Hence, the co-existence of severe primary MR and diabetes mellitus may further activate LA remodeling, leading to impaired LA deformation.

Table 2 Echocardiographic parameters of the study population and relevant factors for severe heart failure symptoms (NYHA III). Total N = 110 LVMi (gm/m2) LVEDVi (ml/m2) LVESVi (ml/m2) LVEF (%) LV GLS (%) E (cm/s) A (cm/s) LAVi (ml/m2) LATEF (%) LASp (%) LASn (%) LASRf (1/s) LASRc (1/s) LASRa (1/s) PASP (mm Hg) EROA (cm2) Regurgitant fraction (%) RVol (ml per beat)

106.9 53.5 14.7 72.6 −20.5 119.4 76.5 42.1 45.3 25.86 −14.70 2.32 −2.12 −2.56 37.3 0.79 54.6 105.2

± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±

NYHA I N = 35 30.2 17.0 6.5 7.3 4.0 0.3 24.4 26.6 14.8 9.89 4.38 0.68 0.75 0.73 20.0 0.6 17.5 66.0

100.0 56.2 15.6 73.3 −21.2 112.0 68.2 36.0 46.8 29.89 −15.61 2.49 −2.38 −2.61 30.8 0.96 54.5 119.7

NYHA II N = 62 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±

28.3 19.6 8.2 7.4 4.4 26.9 18.6 15.7 12.0 8.93 4.45 0.54 0.70 0.71 15.5 0.7 16.3 79.2

106.2 ± 52.4 ± 14.1 ± 72.5 ± −20.3 ± 120.6 ± 79.6 ± 42.5 ± 45.9 ± 25.18 ± −14.36 ± 2.29 ± −2.07 ± −2.56 ± 38.1 ± 0.64 ± 53.8 ± 92.7 ±

NYHA III N = 13 29.1 15.8 5.6 7.6 3.9 33.0 26.2 29.2 16.0 10.09 4.12 0.70 0.78 0.79 18.0 0.5 17.5 60.7

127.7 ± 51.8 ± 15.0 ± 71.3 ± −19.6 ± 135.3 ± 89.8 ± 55.6 ± 37.2 ± 18.82 ± −13.53 ± 1.97 ± −1.70 ± −2.43 ± 50.1 ± 0.89 ± 58.9 ± 112.4 ±

p-Value

33.0 15.0 5.8 6.1 3.1 39.8 24.7 32.6 15.0 6.39 5.47 0.82 0.49 0.44 30.2 0.3 20.5 66.0

0.017 0.547 0.592 0.703 0.417 0.089 0.022 0.074 0.259 0.002 0.308 0.055 0.015 0.795 0.011 0.154 0.634 0.333

Multivariate logistic regression analysisa Odds ratio

95% confidence interval

p-Value

1.020

0.999–1.041

0.059

0.891

0.796–0.997

0.044

0.591 3.178

0.210–1.660 0.878–11.495

0.318 0.078

1.020

0.991–1.050

0.183

NYHA = New York Heart Association functional classification; LVMi = left ventricular mass index; LVEDVi = left ventricular end-diastolic volume index; LVESVi = left ventricular endsystolic volume index; LVEF = left ventricular ejection fraction; LV GLS = global left ventricular peak systolic longitudinal strain; E = transmitral early diastolic velocity; A = transmitral late diastolic velocity; LAVi = left atrial volume index; LATEF = left atrial total emptying fraction; LASp = peak positive strain of left atrium; LASn = peak negative strain of left atrium; LASRf = strain rate in left atrial filling phase; LASRc = strain rate in left atrial conduit phase; LASRa = strain rate in left atrial contraction phase; PASP = pulmonary arterial systolic pressure; EROA = effective regurgitant orifice area; RVol = regurgitant volume. Data are expressed as mean ± SD or number (%). a Adjusted for age and status of atrial fibrillation.

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In conclusion, our study demonstrated that LA strain was independently associated with heart failure symptoms. Age and diabetes mellitus linked to a decreased LA strain in these patients. These findings suggest that assessment of LA deformation is valuable in chronic severe primary MR. References [1] Sarano AE, Akins CW, Vahanian A. Mitral regurgitation. Lancet 2009;373:1382–94. [2] Vahanian A, Alfieri O, Andreotti F, et al. Guidelines on the management of valvular heart disease (version 2012): the Joint Task Force on the Management of Valvular Heart Disease of the European Society of Cardiology (ESC) and the European Association for Cardio-Thoracic Surgery (EACTS). Eur Heart J 2012;33:2451–96. [3] Moustafa SE, Alharthi M, Kansal M, Deng Y, Chandrasekaran K, Mookadam F. Global left atrial dysfunction and regional heterogeneity in primary chronic mitral insufficiency. Eur J Echocardiogr 2011;12:384–93. [4] Shih JY, Tsai WC, Huang YY, et al. Association of decreased left atrial strain and strain rate with stroke in chronic atrial fibrillation. J Am Soc Echocardiogr 2011;24:513–9.

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