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Simplified Peak Power Reserve in Patients With an
Implantable Cardioverter-Defibrillator and Advanced
Heart Failure
William T. Katsiyiannis, MD, Alan D. Waggoner, MHS, Benico Barzilai, MD, Brian F. Gage, MD, MS, Jose M. Sanchez, MD, Joseph G. Rogers, MD, Bruce D. Lindsay, MD, and Marye J. Gleva, MD The prognostic ability of simplified peak power (SPP)
progressive pump failure as opposed to arrhythmic reserve, a novel measure of left ventricular systolic
death. Contractile reserve determined by invasively performance, was prospectively studied in patients
measured peak power has been used as a prognostic with advanced heart failure (HF) and implantable
indicator in patients with Ventricular reserve cardioverter-defibrillators. Reduced SPP reserve iden-
using noninvasive simplified peak power (SPP) is tified patients who are at high risk for experiencing
easily obtained, afterload independent, can be preload progressive HF. ᮊ2005 by Excerpta Medica Inc.
adjusted, and may add additional predictive power to (Am J Cardiol 2005;95:286 –288)
traditional prognostic measures. We conducted a pro-spective study to determine whether noninvasive SPP Some patients with left ventricular dysfunction and reserve can identify ICD candidates with rapidly pro-
ventricular arrhythmias derive limited benefit gressive HF. Our hypothesis was that in patients with from the placement of implantable cardioverter-defi- ICDs in New York Heart Association functional class brillators (ICDs), because they die of progressive III HF, those with limited SPP reserve would have a heart failure (HF). The accurate identification of this greater number of adverse HF events.
group could guide the selection of patients who may benefit from more directed HF therapy. Unfortunately, We prospectively enrolled patients in New York the tools that are currently available to stratify this Heart Association class III HF who underwent ICD population are imprecise. Patients with the most ad- implantation for an American College of Cardiology– vanced HF symptoms are more likely to die from American Heart Association class I indication atBarnes-Jewish Hospital–Washington University School From the Cardiovascular Division, Department of Internal Medicine, of Medicine. Patients with either ischemic or nonisch- Washington University School of Medicine, St. Louis, Missouri. Dr. Katsiy- emic cardiomyopathy were included. Patients were ex- iannis was supported by the Michael Bilitch fellowship of the North cluded for the inability to complete a dobutamine stress echocardiogram (i.e., the development of chest pain, Massachusetts. Dr. Katsiyiannis’s address is: Minneapolis Heart Institute, arrhythmia, or hypotension or hypertension necessitating 920 East Twenty-Eighth St., Suite 300, Minneapolis, Minnesota 55407.
E-mail: wkatsiyiannis@mplsheart.com. Manuscript received June 2, the early discontinuation of the study). A cohort of age- 2004; revised manuscript received and accepted September 8, 2004.
matched control patients without a history of HF or 2005 by Excerpta Medica Inc. All rights reserved.
The American Journal of Cardiology Vol. 95 January 15, 2005 TABLE 1 Characteristics of Patients With HF and ICDs
and where peak poweris equal to the product of peak aortic flow and mean arterial pressure. Peakaortic flow was defined as the prod- square of end-diastolic volume, anestimate of preload: (1) SPP reserve SPP baseline; (2) SPP ϭ aortic flow ϫ mean arterial pressure; (3) aortic flow ϭ aortic annulus area ϫ peak aortic velocity; and (4) mean arterial pressure ϭ ([2 ϫ systolic pressure] ϩ diastolic pressure)/3.
Patients were followed in the Washington Univer- sity Medical Center Arrhythmia Clinic every 3months. At each follow-up visit, clinical informationwas obtained, including a history of shocks, ICDinterrogation, HF hospitalizations, or cardiac trans-plantation. Mortality data were collected from hospitalrecords and family interviews.
The composite end point of HF hospitalizations, cardiac transplantation, and all-cause mortality wasanalyzed by the Kaplan-Meier method. Analyses wereperformed with SPP reserve dichotomized at 1.5W/ml2. This value was chosen a priori on the basis ofa previous Continuous variables were com-pared using the unpaired Student’s t test, and categor- FIGURE 1. Kaplan-Meier curves for the composite end point in
ical variables were compared using Fisher’s exact test.
patients with ICDs and New York Heart Association class III HF.
Analyses were performed using SPSS version 10.0 forWindows (SPSS, Inc., Chicago, Illinois) statisticalsoftware.
arrhythmia was also enrolled and underwent noninvasive Twelve age-matched normal control patients un- SPP reserve measurements only. The Human Studies derwent dobutamine stress echocardiography and Committee of Washington University School of Medi- the determination of SPP reserve. Their mean age cine approved all aspects of the study, and written in- was 61 years. Their mean baseline ejection fraction formed consent was obtained from all participants before was 73 Ϯ 11%, and their mean SPP reserve was 35.2 Ϯ 19 W/ml2. Eighteen patients in New York Dobutamine stress echocardiograms were performed Heart Association class III HF who had ICDs were beginning at an initial dose of 5 ␮g · kgϪ1 · minϪ1 for 3 enrolled. Their mean age was 61 years. Their mean minutes, followed by 10 ␮g · kgϪ1 · minϪ1 for 3 min- baseline ejection fraction was 32 Ϯ 11%, and their utes, with subsequent dose increments of 10 ␮g · kgϪ1 · mean SPP reserve was 3.5 Ϯ 3.2 W/ml2.
minϪ1 every 3 minutes, up to a maximum of 40 ␮g · SPP reserve discriminated HF patients from con- kgϪ1 · minϪ1. The infusions were discontinued when the trols without overlap (mean 3.5, range 0.05 to 10.34 vs patients achieved 85% of their target heart rate for their mean 35.2, range 21.8 to 51.3, respectively; p age group or if chest pain, ST-segment depression, or Ͻ0.0001). The study population had a mean follow-up new regional wall motion abnormalities developed.
of 15.5 months. There were no differences in the Echocardiograms at rest and dobutamine stress echocar- baseline characteristics of the 2 groups of patients diograms were used to determine the left ventricular with HF and ICDs: those with adequate (Ͼ1.5 W/ml2) was 1 death, 1 heart transplantation, and 3 HF hospi- predict survival in patients with ICDs and is not easily talizations in the group with poor SPP reserve and no measured in patients with more advanced HF and those end points in the group with adequate SPP reserve.
There were 4 ICD shocks in the group with poor SPP Therefore, an ideal prognostic tool would have the reserve and 1 ICD shock in the group with adequate predictive power of VO max, be noninvasive, and be SPP reserve. Kaplan-Meier analysis of the composite easy to use in patients with advanced HF. One such end point of death, heart transplantation, or HF hos- instrument that has emerged as a novel echocardio- pitalization showed a significantly (p ϭ 0.02) greater graphic measure of ventricular function is SPP re- event rate in the group with poor SPP reserve serve. It has an advantage over other echocardio- SPP reserve discriminated the 2 groups of patients graphic measures in that it is not significantly affected with HF and ICDs without overlap, whereas the ejec- by afterload, can be adjusted for and corre- tion fraction showed considerable overlap. The mean lates well with VO The present study demon- SPP reserve of the group with death or transplantation strates that SPP reserve identifies patients with ad- was 0.63 Ϯ 0.4 W/ml2, and the mean SPP reserve of vanced HF and ICDs who are more likely to have the surviving patients was 4.9 Ϯ 2.3 W/ml2 (p ϭ For ICDs to show a continued survival benefit in patients with advanced HF, the risk for sudden cardiac 1. Marmor A, Schneeweiss A. Prognostic value of noninvasively obtained left
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288 THE AMERICAN JOURNAL OF CARDIOLOGYா

Source: https://circl.wustl.edu/Published%20Research/pdf/Peak%20power%20AJC%202005.pdf