title: Prognostic value of cardiac power output to left ventricular mass in patients with left ventricular dysfunction and dobutamine stress echo negative by wall motion criteria.
abstract: OBJECTIVE
  Cardiac power output to left ventricular mass (power/mass) is an index of myocardial efficiency reflecting the rate at which cardiac work is delivered with respect to the potential energy stored in the left ventricular mass. In the present study, we sought to investigate the capability of power/mass assessed at peak of dobutamine stress echocardiography to predict mortality in patients with ischaemic cardiomyopathy and no inducible ischaemia.
  
  
  RESULTS
  One-hundred eleven patients (95 males; age 68 ± 10 years) with 35 ± 7% mean left ventricular ejection fraction and a dobutamine stress echocardiography (up to 40 µg/kg/min) negative by wall motion criteria formed the study population. Power/mass at peak stress was obtained as the product of a constant (K = 2.22 × 10-1) with cardiac output and the mean arterial pressure divided by left ventricular mass to convert the units to W/100 g. Patients were followed up for a median of 29 months (inter-quartile range 16-72 months). All-cause mortality was the only accepted clinical end point. Mean peak-stress power/mass was 0.70 ± 0.31 W/100 g. During follow-up, 29 deaths (26%) were registered. With a receiver operating characteristic analysis, a peak-stress power/mass ≤0.50 W/100 g [area under curve 0.72 (95% CI 0.63; 0.80), sensitivity 59%, specificity 80%] was the best value for predicting mortality. Univariate prognostic indicators were age, male sex, peak-stress ejection fraction, peak-stress stroke volume, peak-stress cardiac output, peak-stress cardiac power output ≤1.48 W, and peak-stress power/mass ≤0.50 W/100 g. At multivariate analysis, age (HR 1.08, 95% CI 1.04; 1.14; P = 0.004) and peak-stress power/mass ≤0.50 W/100 g (HR 4.05, 95% CI 1.36; 12.00; P = 0.01) provided independent prognostic information. Three-year mortality was 14% in patients with peak-stress power/mass >0.50 W/100 g and 47% in those with peak-stress power/mass ≤0.50 W/100 g (log-rank 20.4; P < 0.0001).
  
  
  CONCLUSIONS
  Power/mass assessed at peak of dobutamine stress echocardiography allows effective prognostication in patients with ischaemic cardiomyopathy and test result negative by wall motion criteria. In particular, a peak-stress power/mass ≤50 W/100 g is a strong and multivariable predictor of mortality.
authors.affiliation: Division of Cardiology, San Luca Hospital, Lucca, Italy.
authors.forename: Lauro
authors.initials: L
authors.lastname: Cortigiani
authors.affiliation: Cardiac, Thoracic and Vascular Department, University Hospital of Pisa, Azienda Universitaria-Ospedaliera Pisana, Via Paradisa, 2, Pisa 56124, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: Sorbo
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Miccoli
authors.affiliation: Cardiac, Thoracic and Vascular Department, University Hospital of Pisa, Azienda Universitaria-Ospedaliera Pisana, Via Paradisa, 2, Pisa 56124, Italy.
authors.forename: Maria Chiara
authors.initials: MC
authors.lastname: Scali
authors.affiliation: Cardiac, Thoracic and Vascular Department, University Hospital of Pisa, Azienda Universitaria-Ospedaliera Pisana, Via Paradisa, 2, Pisa 56124, Italy.
authors.forename: Anca
authors.initials: A
authors.lastname: Simioniuc
authors.affiliation: Cardiac, Thoracic and Vascular Department, University Hospital of Pisa, Azienda Universitaria-Ospedaliera Pisana, Via Paradisa, 2, Pisa 56124, Italy.
authors.forename: Doralisa
authors.initials: D
authors.lastname: Morrone
authors.affiliation: Division of Cardiology, San Luca Hospital, Lucca, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Bovenzi
authors.affiliation: Cardiac, Thoracic and Vascular Department, University Hospital of Pisa, Azienda Universitaria-Ospedaliera Pisana, Via Paradisa, 2, Pisa 56124, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Marzilli
authors.affiliation: Cardiac, Thoracic and Vascular Department, University Hospital of Pisa, Azienda Universitaria-Ospedaliera Pisana, Via Paradisa, 2, Pisa 56124, Italy f.dini@ao-pisa.toscana.it.
authors.forename: Frank Lloyd
authors.initials: FL
authors.lastname: Dini
mesh_terms: D000368:Aged; D002302:Cardiac Output / Q000502:physiology*; D002311:Cardiomyopathy, Dilated / Q000000981:diagnostic imaging / Q000401:mortality* / Q000503:physiopathology; D002423:Cause of Death; D015331:Cohort Studies; D025401:Echocardiography, Stress; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000502:physiology*; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging / Q000503:physiopathology; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012372:ROC Curve; D015203:Reproducibility of Results; D018570:Risk Assessment; D013318:Stroke Volume / Q000502:physiology; D016019:Survival Analysis; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging / Q000401:mortality* / Q000503:physiopathology
keywords: cardiac power output; dobutamine stress echocardiography; left ventricular dysfunction