title: Factors influencing exercise performance in patients with left ventricular dysfunction. SOLVD Investigators. Studies of Left Ventricular Dysfunction.
abstract: BACKGROUND
  The determinants of exercise performance are multifactorial and incompletely understood in patients with symptomatic left ventricular (LV) dysfunction, with much less information regarding asymptomatic LV dysfunction. This study assessed the hemodynamics and neurohormonal factors influencing exercise performance in patients with LV ejection fractions > or =0.35, both symptomatic and asymptomatic, enrolled in Studies of LV Dysfunction.
  
  
  RESULTS
  We studied 103 patients enrolled prospectively in Studies of LV Dysfunction before randomized therapy; 38 were symptomatic and 65 had no or minimal symptoms. By using rest-exercise gated equilibrium radionuclide ventriculography and cuff blood pressure, we assessed the heart rate, LV and right ventricular (RV) volumes and ejection fractions, total peripheral resistance, the LV peak systolic pressure/end systolic volume ratio as an index of contractility, and plasma renin and norepinephrine at rest and during maximal graded supine bicycle ergometer exercise. Changes between rest and exercise were evaluated as indices of cardiovascular reserve. The cumulative workload ranged from 120 to 2,100 watt-min. At rest, the LV ejection fraction was 0.30 in asymptomatic patients and 0.25 in symptomatic patients, respectively (P < .0004). During exercise, asymptomatic patients had greater increases in heart rate, systolic blood pressure, LV ejection fraction, and cardiac output than symptomatic patients (P > or = .05). Combining all patients, the strongest univariate correlates of exercise workload were the ability to increase heart rate (r = 0.70), the pressure/volume ratio (r = 0.63), and systolic blood pressure (r = 0.55), and to decrease the total peripheral resistance (r = -0.47) with moderate correlations for the ability to increase LV and RV ejection fractions (r = 0.33 and 0.35, respectively) (P < .0008). By multivariate analysis, workload was modeled best by the changes in four factors: heart rate, systolic blood pressure, and the LV and RV ejection fractions (R2 = 0.54, P < .001).
  
  
  CONCLUSIONS
  Exercise performance and its hemodynamics differed in patients with symptomatic and asymptomatic LV dysfunction. Rather than features at rest, the reserve capacities for increasing heart rate, systolic blood pressure, and the LV and RV ejection fractions were the predominant cardiac mechanisms related to greater exercise performance.
authors.affiliation: Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
authors.forename: M W
authors.initials: MW
authors.lastname: Kronenberg
authors.forename: M A
authors.initials: MA
authors.lastname: Konstam
authors.forename: T R
authors.initials: TR
authors.lastname: Edens
authors.forename: D M
authors.initials: DM
authors.lastname: Howe
authors.forename: N
authors.initials: N
authors.lastname: Dolan
authors.forename: J E
authors.initials: JE
authors.lastname: Udelson
authors.forename: C
authors.initials: C
authors.lastname: Benedict
authors.forename: D
authors.initials: D
authors.lastname: Stewart
authors.forename: S
authors.initials: S
authors.lastname: Yusuf
mesh_terms: D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000187:drug effects; D004071:Digitalis Glycosides / Q000494:pharmacology / Q000627:therapeutic use; D004232:Diuretics / Q000494:pharmacology / Q000627:therapeutic use; D004311:Double-Blind Method; D015444:Exercise; D005080:Exercise Test; D005260:Female; D015637:Gated Blood-Pool Imaging / Q000379:methods; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009566:Nitrates / Q000494:pharmacology / Q000627:therapeutic use; D009638:Norepinephrine / Q000097:blood; D011446:Prospective Studies; D013318:Stroke Volume / Q000187:drug effects; D013667:Technetium; D014655:Vascular Resistance / Q000187:drug effects; D018487:Ventricular Dysfunction, Left / Q000188:drug therapy / Q000503:physiopathology*; D016526:Workload
chemical_list: D004071:Digitalis Glycosides; D004232:Diuretics; D009566:Nitrates; D013667:Technetium; D009638:Norepinephrine