title: Respiratory muscle dysfunction in congestive heart failure: clinical correlation and prognostic significance.
abstract: BACKGROUND
  In congestive heart failure (CHF), the prognostic significance of impaired respiratory muscle strength has not been established.
  
  
  RESULTS
  Maximal inspiratory pressure (Pi(max)) was prospectively determined in 244 consecutive patients (207 men) with CHF (ischemic, n=75; idiopathic dilated cardiomyopathy, n=169; age, 54+/-11 years; left ventricular ejection fraction [LVEF], 22+/-10%). Pi(max) was lower in the 244 patients with CHF than in 25 control subjects (7.6+/-3.3 versus 10.5+/-3.7 kPa; P=0.001). The 57 patients (23%) who died during follow-up (23+/-16 months; range, 1 to 48 months) had an even more reduced Pi(max) (6.3+/-3.2 versus 8.1+/-3.2 kPa in survivors; P=0.001). Kaplan-Meier survival curves differentiated between patients subdivided according to quartiles for Pi(max) (P=0.014). Pi(max) was a strong risk predictor in both univariate (P=0.001) and multivariate Cox proportional hazard analyses (P=0.03); multivariate analyses also included NYHA functional class, LVEF, peak oxygen consumption (peak VO(2)), and norepinephrine plasma concentration. The areas under the receiver-operating characteristic curves for prediction of 1-year survival were comparable for Pi(max) and peak VO(2) (area under the curve [AUC], 0.68 versus 0.73; P=0.28), and they improved with the triple combination of Pi(max), peak VO(2), and LVEF (AUC, 0.82; P=0.004 compared with AUC of Pi(max)).
  
  
  CONCLUSIONS
  In patients with CHF, inspiratory muscle strength is reduced and emerges as a novel, independent predictor of prognosis. Because testing for Pi(max) is simple in clinical practice, it might serve as an additional factor to improve risk stratification and patient selection for cardiac transplantation.
authors.affiliation: Department of Cardiology, Angiology, and Respiratory Medicine, Medical Center of the University Heidelberg, Heidelberg, Germany.
authors.forename: F J
authors.initials: FJ
authors.lastname: Meyer
authors.forename: M M
authors.initials: MM
authors.lastname: Borst
authors.forename: C
authors.initials: C
authors.lastname: Zugck
authors.forename: A
authors.initials: A
authors.lastname: Kirschke
authors.forename: D
authors.initials: D
authors.lastname: Schellberg
authors.forename: W
authors.initials: W
authors.lastname: Kübler
authors.forename: M
authors.initials: M
authors.lastname: Haass
mesh_terms: D000328:Adult; D000368:Aged; D019540:Area Under Curve; D002311:Cardiomyopathy, Dilated / Q000150:complications / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000209:etiology / Q000401:mortality / Q000503:physiopathology*; D006801:Humans; D015993:Life Tables; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000150:complications / Q000503:physiopathology; D010101:Oxygen Consumption; D011379:Prognosis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012372:ROC Curve; D012129:Respiratory Function Tests; D012132:Respiratory Muscles / Q000503:physiopathology*; D013318:Stroke Volume