title: Noninvasive assessment of left ventricular stroke work index in patients with severe mitral regurgitation: correlation with invasive measurement and exercise capacity.
abstract: BACKGROUND
  Noninvasively measured left ventricular stroke work index (LVSWI) may be an ideal indicator that can provide more relevant information about cardiac performance in severe mitral regurgitation (MR). We sought to correlate the noninvasive LVSWI with invasive measure of LVSWI and validate its clinical usefulness by comparing the noninvasive LVSWI with exercise capacity.
  
  
  METHODS
  Twenty-nine patients with severe MR who underwent cardiac catheterization and 61 patients with severe MR who underwent cardiopulmonary exercise test were evaluated for comparison of noninvasive LVSWI with invasive LVSWI via cardiac catheterization and peak exercise capacity, respectively.
  
  
  RESULTS
  Mean noninvasive LVSWI was 33.1 ± 9.7 g·m/m², which was in a good agreement with invasive LVSWI (34.9 ± 15.1 g·m/m², intraclass correlation coefficient = 0.72, P < 0.001). Noninvasive LVSWI (β= 0.35, P = 0.001) was independently related with peak exercise capacity. Indexed left atrial volume (β=-0.27, P = 0.042), mean blood pressure (β=-0.21, P = 0.030), age (β=-0.47, P < 0.001) estimated pulmonary artery systolic pressure (β=-0.21, P = 0.030) and male gender (β= 0.36, P = 0.001) were also independently associated with exercise capacity.
  
  
  CONCLUSIONS
  Noninvasive LVSWI has a good correlation with invasively measured LVSWI and is a clinically useful parameter for evaluating true cardiac performance in patients with severe MR.
authors.affiliation: Division of Cardiology, Cardiac and Vascular Center, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Jin-Oh
authors.initials: JO
authors.lastname: Choi
authors.forename: Sang-Chol
authors.initials: SC
authors.lastname: Lee
authors.forename: Soo Hee
authors.initials: SH
authors.lastname: Choi
authors.forename: Sang Min
authors.initials: SM
authors.lastname: Kim
authors.forename: Joon Hyouk
authors.initials: JH
authors.lastname: Choi
authors.forename: Jeong Rang
authors.initials: JR
authors.lastname: Park
authors.forename: Bong Gun
authors.initials: BG
authors.lastname: Song
authors.forename: Sung-A
authors.initials: SA
authors.lastname: Chang
authors.forename: Sung-Ji
authors.initials: SJ
authors.lastname: Park
authors.forename: Seung Woo
authors.initials: SW
authors.lastname: Park
authors.forename: Pyo Won
authors.initials: PW
authors.lastname: Park
mesh_terms: D004452:Echocardiography / Q000379:methods*; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008944:Mitral Valve Insufficiency / Q000150:complications* / Q000175:diagnosis* / Q000503:physiopathology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D013318:Stroke Volume; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000209:etiology* / Q000503:physiopathology