title: Stroke-work loss underestimates hemodynamic significance of aortic stenosis in patients with hypertension.
abstract: BACKGROUND
  Stroke-work loss (SWL) represents the amount of energy the left ventricle dissipates as heat because of outflow obstruction. Recent studies suggest that SWL > 25% was the most clinically efficient Doppler measure for predicting hemodynamic significance, symptomatic status, and outcome in patients with aortic stenosis (AS). However, SWL may be affected by systolic blood pressure (SBP).
  
  
  OBJECTIVE
  To determine if SWL reliably predicts hemodynamic significance of AS in patients with hypertension.
  
  
  METHODS
  We studied 42 consecutive patients with hemodynamically significant AS requiring aortic valve replacement (AVR). Data on demographics, preoperative hemodynamics, and echocardiographic parameters were obtained. SWL was measured using the formula SWL = 100 x mean PG/ (mean PG + SBP), where PG is transaortic pressure gradient. Patients were considered hypertensive if their BP > 140/90 mmHg or if they are on antihypertensive medications.
  
  
  RESULTS
  There were 27 males (64%) and mean age was 68 +/- 11 years. Twenty-four patients (57%) were hypertensive. Mean SBP was 134 +/- 24 mmHg, mean transaortic PG 47 +/- 20 mmHg, effective valve orifice area (EOA) by Doppler estimation 0.74 +/- 0.23 cm(2), and SWL 26 +/- 9%. Patients with hypertension had smaller SWL than normotensives (table I). SWL was >25% in 20 (49%) patients, and fewer patients with hypertension have SWL >25% (33% vs 71%, P = 0.019). Of note, patients with SWL < or =25% had significantly higher SBP (145 +/- 21 mmHg vs 122 +/- 22 mmHg, P = 0.02).
  
  
  CONCLUSIONS
  SWL underestimates the hemodynamic significance of aortic stenosis in the majority of patients with hypertension.
authors.affiliation: The Cardiac Department, National University Hospital, Singapore. raymond_cc_wong@nuh.com.sg
authors.forename: Raymond Ching-Chiew
authors.initials: RC
authors.lastname: Wong
authors.forename: Tiong Cheng
authors.initials: TC
authors.lastname: Yeo
mesh_terms: D000368:Aged; D001024:Aortic Valve Stenosis / Q000150:complications* / Q000000981:diagnostic imaging*; D015150:Echocardiography, Doppler / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013318:Stroke Volume; D014694:Ventricular Outflow Obstruction / Q000150:complications* / Q000000981:diagnostic imaging*