title: Comparison of the prognostic values of invasive and noninvasive assessments of baroreflex sensitivity in heart failure.
abstract: OBJECTIVE
  No studies have compared the prognostic values of invasive (phenylephrine, Phe) and noninvasive (transfer function) assessments of baroreflex sensitivity (BRS).
  
  
  METHODS
  Three hundred and one heart failure patients [age: 53 ± 8 years, New York Heart Association class II-III: 88%, left-ventricular ejection fraction (LVEF): 28 ± 8%] underwent an 8 min ECG and arterial pressure recording, followed by Phe administration.
  
  
  RESULTS
  Phe-BRS and transfer function BRS (TF-BRS) could be measured in 89 and 72% of cases, respectively. The correlation and the 5-95th percentiles of the difference between the two methods were 0.61 (P < 0.0001), and -7.6, +7.5 ms/mmHg, respectively. During a median of 36 months, 23% of the patients experienced a cardiac event. In the common dataset of 202 patients, both BRS measurements (<3 ms/mmHg) were significantly associated with the outcome (both P < 0.001), but Phe-BRS had a better discriminatory power (area under the curve (AUC): 0.74 vs. 0.66, P  = 0.03). Patients with a missing BRS (due to high grade ectopic activity) had a higher event rate (Phe-BRS: 38 vs. 24%, P  = 0.23; TF-BRS: 37 vs. 19%, P  = 0.002). Using this information, a prognostic index was derived for each BRS method, increasing measurability to 94 and 98%, respectively. Both indexes significantly predicted the outcome after adjustment for clinical covariates [hazard ratio (95% CI): 1.9 (1.1-3.3), P  = 0.03 for Phe index and 2.0 (1.1-3.7), P  = 0.02 for transfer function index].
  
  
  CONCLUSIONS
  Although the measurability of TF-BRS in heart failure patients is impaired, prognostic information can be extended to almost all patients, with a predictive power similar to that of Phe-BRS. The two measurements, however, convey a certain amount of independent prognostic information. Hence, TF-BRS can be integrated with but not replace Phe-BRS.
authors.affiliation: Department of Cardiology, S. Maugeri Foundation, IRCCS Scientific Institute of Montescano, Montescano, Pavia, Italy. mariateresa.larovere@fsm.it
authors.forename: Maria T
authors.initials: MT
authors.lastname: La Rovere
authors.forename: Roberto
authors.initials: R
authors.lastname: Maestri
authors.forename: Elena
authors.initials: E
authors.lastname: Robbi
authors.forename: Angelo
authors.initials: A
authors.lastname: Caporotondi
authors.forename: Gianpaolo
authors.initials: G
authors.lastname: Guazzotti
authors.forename: Oreste
authors.initials: O
authors.lastname: Febo
authors.forename: Gian D
authors.initials: GD
authors.lastname: Pinna
mesh_terms: D017704:Baroreflex / Q000187:drug effects* / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D003955:Diagnostic Tests, Routine / Q000379:methods; D004562:Electrocardiography; D005260:Female; D006333:Heart Failure / Q000175:diagnosis* / Q000503:physiopathology*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D010656:Phenylephrine / Q000494:pharmacology*; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D015656:Respiratory Mechanics / Q000502:physiology*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014662:Vasoconstrictor Agents / Q000494:pharmacology
chemical_list: D014662:Vasoconstrictor Agents; D010656:Phenylephrine