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ABSTRACT: About 50% or more of heart failure (HF) patients living in the community have preserved left ventricular ejection fraction (HFpEF), and the proportion is higher among women and the very elderly. A cardinal feature of HFpEF is reduced aerobic capacity, measured objectively as peak exercise pulmonary oxygen uptake (peak VO(2)), that results in decreased quality of life. Specifically, peak VO(2) of HFpEF patients is 30-70% lower than age-, sex-, and comorbidity-matched control patients without HF. The mechanisms for the reduced peak VO(2) are due to cardiovascular and skeletal muscle dysfunction that results in reduced oxygen delivery to and/or utilization by the active muscles. Currently, four randomized controlled exercise intervention trials have been performed in HFpEF patients. These studies have consistently demonstrated that 3-6 months of aerobic training performed alone or in combination with strength training is a safe and effective therapy to increase aerobic capacity and endurance and quality of life in HFpEF patients. Despite these benefits, the physiologic mechanisms underpinning the improvement in peak exercise performance have not been studied; therefore, future studies are required to determine the role of physical training to reverse the impaired cardiovascular and skeletal muscle function in HFpEF patients.
Current Heart Failure Reports 03/2012; 9(2):101-6.
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Journal of the American College of Cardiology 12/2011; 58(24):2548-9. · 14.16 Impact Factor
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ABSTRACT: Previous research has demonstrated the prognostic value of cardiopulmonary exercise testing (CPX) in elderly patients with heart failure (HF). Investigations that have comprehensively examined the value of CPX across different age groups are lacking. The purpose of the present investigation was to evaluate the prognostic value of CPX in young, middle-aged and older patients with HF.
A total of 1605 subjects (age: 59.2 ± 13.7 years, 78% male) underwent CPX and were subsequently tracked for major cardiac events. Ventilatory efficiency (VE/VCO(2) slope) and peak oxygen consumption (VO(2)), both absolute and percent-predicted, were determined. The prognostic value of these CPX variables was assessed in ≤ 45, 46-65 and ≥ 66 year subgroups.
The three year event rates for major cardiac events in the ≤ 45, 46-65 and ≥ 66 year subgroups were 8.8%, 6.0% and 5.7%, respectively. The VE/VCO(2) slope (Hazard ratio ≥ 1.07, p<0.001), peak VO(2) (Hazard ratio ≤ 0.87, p<0.001) and percent-predicted peak VO(2) (Hazard ratio 0 ≤ 0.98, p<0.001) were all significant prognostic markers in each age subgroup. While the VE/VCO(2) slope carried the greatest prognostic strength, peak VO(2) and percent-predicted peak VO(2) were retained in multivariate analyses (Residual Chi-Square ≥ 5.2, p<0.05). With respect to peak VO(2), the actual value was the more robust prognostic marker in the ≤ 45 and ≥ 66 year subgroups while the percent-predicted expression provided better predictive resolution in subjects who were 46-65 years old.
These results indicate that, irrespective of a patient's age at presentation, CPX provides valuable prognostic information in the HF population.
International journal of cardiology 09/2011; 151(3):278-83. · 7.08 Impact Factor
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ABSTRACT: Standards for estimating maximal HR are important when interpreting the adequacy of physiologic stress during exercise testing, assessing chronotropic response, and prescribing an exercise training regimen. The equation 220 - age is used to estimate maximum HR; however, it overestimates measured maximal HR in patients taking β-adrenergic blockade (βB) therapy. This study developed and validated a practical equation to predict maximal HR in patients with heart failure (HF) taking βB therapy.
Data from symptom-limited exercise tests completed on patients with systolic HF participating in the Heart Failure: A Controlled Trial Investigating Outcomes of Exercise Training trial and taking a βB agent were used to develop a simplified equation, which was validated using bootstrapping.
The simplified derived equation was 119 + 0.5 (resting HR) - 0.5 (age) - (0, if test was completed using a treadmill; 5, if using a stationary bike). The R2 and SEE were 0.28 and 18 beats·min(-1), respectively. Validation of this equation yielded a mean R and SEE of 0.28 and 18 beats·min(-1), respectively. For the equation 220 - age, the R2 was -2.93, and the SEE was 43 beats·min(-1).
We report a valid and simple population-specific equation for estimating peak HR in patients with HF taking βB therapy. This equation should be helpful when evaluating chronotropic response or assessing if a maximum effort was provided during exercise testing. We caution, however, that the magnitude of the variation (SEE = 18 beats·min(-1)) associated with this prediction equation may make it impractical when prescribing exercise intensity.
Medicine and science in sports and exercise 09/2011; 44(3):371-6. · 3.71 Impact Factor
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ABSTRACT: Underwater treadmill (UTM) exercise is being used with increased frequency for rehabilitation of injured athletes, yet there has been little research conducted on this modality.
To determine the cardiorespiratory responses of UTM vs land treadmill (LTM) exercise, particularly with respect to the relationship between heart rate (HR) and oxygen consumption (VO2).
This quantitative original research took place in sports medicine and athletic training facilities at Wake Forest University.
11 Wake Forest University student athletes (20.8 ± 0.6 y, 6 women and 5 men).
All participants completed the UTM and LTM exercise-testing protocols in random order. After 5 min of standing rest, both UTM and LTM protocols had 4 stages of increasing belt speed (2.3, 4.9, 7.3, and 9.6 km/h) followed by 3 exercise stages at 9.6 km/h with increasing water-jet resistance (30%, 40%, and 50% of jet capacity) or inclines (1%, 2%, and 4% grade).
A Cosmed K4b2 device with Polar monitor was used to collect HR, ventilation (Ve), tidal volume (TV), breathing frequency (Bf), and VO2 every minute. Ratings of perceived exertion (RPE) were also obtained each minute.
There was no significant difference between UTM and LTM for VO2 at rest or during any stage of exercise except stage 3. Furthermore, there were no significant differences between UTM and LTM for HR, Ve, Bf, and RPE on any exercise stage. Linear regression of HR vs VO2, across all stages of exercise, indicates a similar relationship in these variables during UTM (r = .94, y = .269x - 10.86) and LTM (r = .95, y = .291x - 12.98).
These data indicate that UTM and LTM exercise elicits similar cardiorespiratory responses and that HR can be used to guide appropriate exercise intensity for college athletes during UTM.
Journal of sport rehabilitation 08/2011; 20(3):345-54. · 1.07 Impact Factor
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ABSTRACT: Most elderly persons with heart failure have a preserved left ventricular (LV) ejection fraction (HFPEF). The pathophysiology of this disorder is not well understood, and there are conflicting data regarding the role of decreased LV distensibility. To assess LV distensibility over a range of preload conditions while minimizing the large, confounding changes in contractility, afterload, and heart rate characteristic of exercise, we measured LV end-diastolic volume (EDV), stroke volume (SV), and cardiac output (CO) using two-dimensional echocardiography in 48 elderly (mean age, 69 yr) HFPEF patients and 25 healthy age-matched controls during quiet supine rest, 45 degrees head-up tilt (HUT), and 45 degrees head-down tilt (HDT). As a result, when compared with controls, HFPEF patients had reduced percent changes in EDV (-7 +/- 2 vs. -17 +/- 2%; P = 0.003), SV (-7 +/- 3 vs. -27 +/- 2%; P = 0.003), and CO (-6 +/- 4 vs. -34 +/- 4%; P = 0.001) during the transition from supine to HUT. HFPEF also had reduced percent changes in EDV (8 +/- 2 vs. 15 +/- 2%; P = 0.02), SV (11 +/- 3 vs. 21 +/- 3%; P = 0.002), and CO (1 +/- 4 vs. 12 +/- 4%; P = 0.04) during the transition from HUT to HDT. In conclusion, HFNEF patients have reduced LV distensibility in response to postural change, resulting in blunted EDV, SV, and CO. This provides further support for the hypothesis that a blunted Frank-Starling mechanism may contribute to the pathophysiology of HFPEF.
AJP Heart and Circulatory Physiology 09/2010; 299(3):H883-9. · 3.71 Impact Factor
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Ross Arena,
Jonathan Myers,
Joshua Abella,
Sherry Pinkstaff, Peter Brubaker,
Dalane Kitzman,
Mary Ann Peberdy,
Daniel Bensimhon,
Paul Chase,
Daniel E Forman,
Marco Guazzi
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ABSTRACT: Ventilatory efficiency (VE/VCO(2) slope) and peak oxygen consumption (VO) provide robust prognostic information in patients with heart failure undergoing cardiopulmonary exercise testing (CPX). The purpose of this study is to assess the change in prognostic characteristics of CPX at different time intervals.
Seven hundred ninety-one subjects (74% male, mean age: 60.7+/-12.9 years, ejection fraction: 34.6+/-15.0%, ischemic etiology: 51%) underwent CPX and were tracked for major cardiac events over a 4-year period. All event-free subjects were tracked for at least 3 years. Mean VE/VCO(2) slope and peak VO(2) were 35.0+/-10.0 and 16.0+/-6.4 mL O(2) . kg(-1) . min(-1), respectively. There were a total of 263 major cardiac events (199 deaths, 45 transplants, and 19 left ventricular assist device implantations). Both continuous and dichotomous expressions of the VE/VCO(2) slope and peak VO(2) were prognostically significant up to 18 months post-CPX. Continuous and dichotomous expressions of the VE/VCO(2) slope remained prognostically significant up to 36 months post-CPX, whereas peak VO(2) was not predictive during the third and fourth year of follow-up. In a multivariate analysis, the VE/VCO(2) slope was consistently the superior prognostic marker, whereas peak VO(2) added predictive value and was retained in the regression up to 18 months post-CPX.
These results indicate that commonly assessed CPX variables retain prognostic value for at least 2 years. The VE/VCO(2) slope is the superior predictor of adverse events throughout follow-up, although peak VO(2) provides additive prognostic information during the first 2 years of follow-up.
Circulation Heart Failure 03/2010; 3(3):405-11. · 6.29 Impact Factor
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The American journal of cardiology 03/2010; 105(5):757-8. · 3.58 Impact Factor
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ABSTRACT: The effects of self-monitoring number of steps/day versus minutes of moderate to vigorous-intensity physical activity (MVPA/day) were compared to determine which is more effective for increasing physical activity levels.
A total of 18 participants of a university-based chronic disease prevention program (age 61 +/- 12 years) were enrolled in the 3-week intervention. Subjects were randomly assigned to a group (n = 8) that wore a New Lifestyles accelerometer (NL-1000) and were instructed to increase minutes of MVPA to 30 min/d or more (MIN) or to a group (n = 10) that wore a New Lifestyles pedometer (NL-800) and were instructed to increase the number of steps/day to 10,000 or more (STE). To objectively assess changes in physical activity levels, subjects in both groups simultaneously wore a Lifecorder-EX accelerometer (with display blank) during the intervention.
The number of steps increased significantly in the MIN (10,810 +/-3,211 to 13,355 +/- 3,498 steps/day) and STE (11,517 +/- 3,383 to 12,809 +/-2,479 steps/day) from the first to fourth weeks, respectively. However, the time spent in MVPA increased significantly only in MIN group (36 +/- 11 to 52 +/- 15 min/d) but not in the STE group (32 +/- 7 to 37 +/- 11 min/d) from the first to fourth weeks, respectively.
Data suggest that individuals with chronic disease conditions can more effectively increase levels of physical activity, expressed as both MVPA/day and steps/day, by self-monitoring MIN rather than STE. The effect of self-monitoring physical activity levels for longer periods and/or the effect of increasing minutes of MVPA/day versus steps/day on specific health outcomes have not yet been examined.
Journal of cardiopulmonary rehabilitation and prevention 11/2009; 30(2):111-5. · 1.69 Impact Factor
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Jonathan Myers,
Ross Arena,
Ricardo B Oliveira,
Daniel Bensimhon,
Leon Hsu,
Paul Chase,
Marco Guazzi, Peter Brubaker,
Brian Moore,
Dalane Kitzman,
Mary Ann Peberdy
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ABSTRACT: The lowest minute ventilation (VE) and carbon dioxide production (VCO(2)) ratio during exercise has been suggested to be the most stable and reproducible marker of ventilatory efficiency in patients with heart failure (HF). However, the prognostic power of this index is unknown.
A total of 847 HF patients underwent cardiopulmonary exercise testing (CPX) and were followed for 3 years. The associations between the lowest VE/VCO(2) ratio, maximal oxygen uptake (peak VO(2)), the VE/VCO(2) slope, and major events (death or transplantation) were evaluated using proportional hazards analysis; adequacy of the predictive models was assessed using Akaike information criterion (AIC) weights. There were 147 major adverse events. In multivariate analysis, the lowest VE/VCO(2) ratio (higher ratio associated with greater risk) was similar to the VE/VCO(2) slope in predicting risk (hazard ratios [HR] per unit increment 2.0, 95% CI 1.1-3.4, and 2.2, 95% CI 1.3-3.7, respectively; P < .01), followed by peak VO(2) (HR 1.6, 95% CI 1.1-2.4, P=.01). Patients exhibiting abnormalities for all 3 responses had an 11.6-fold higher risk. The AIC weight for the 3 variables combined (0.94) was higher than any single response or any combination of 2. The model including all 3 responses remained the most powerful after adjustment for beta-blocker use, type of HF, and after applying different cut points for high risk.
The lowest VE/VCO(2) ratio adds to the prognostic power of conventional CPX responses in HF.
Journal of cardiac failure 11/2009; 15(9):756-62. · 3.25 Impact Factor
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ABSTRACT: Older heart failure (HF) patients exhibit exercise intolerance during activities of daily living. We hypothesized that reduced lower extremity blood flow (LBF) due to reduced forward cardiac output would contribute to submaximal exercise intolerance in older HF patients.
Twelve HF patients both with preserved and reduced left ventricular ejection fraction (LVEF) (aged 68 +/- 10 years) without large (aorta) or medium sized (iliac or femoral artery) vessel atherosclerosis, and 13 age and gender matched healthy volunteers underwent a sophisticated battery of assessments including a) peak exercise oxygen consumption (peak VO2), b) physical function, c) cardiovascular magnetic resonance (CMR) submaximal exercise measures of aortic and femoral arterial blood flow, and d) determination of thigh muscle area. Peak VO2 was reduced in HF subjects (14 +/- 3 ml/kg/min) compared to healthy elderly subjects (20 +/- 6 ml/kg/min) (p = 0.01). Four-meter walk speed was 1.35 +/- 0.24 m/sec in healthy elderly verses 0.98 +/- 0.15 m/sec in HF subjects (p < 0.001). After submaximal exercise, the change in superficial femoral LBF was reduced in HF participants (79 +/- 92 ml/min) compared to healthy elderly (222 +/- 108 ml/min; p = 0.002). This occurred even though submaximal stress-induced measures of the flow in the descending aorta (5.0 +/- 1.2 vs. 5.1 +/- 1.3 L/min; p = 0.87), and the stress-resting baseline difference in aortic flow (1.6 +/- 0.8 vs. 1.7 +/- 0.8 L/min; p = 0.75) were similar between the 2 groups. Importantly, the difference in submaximal exercise induced superficial femoral LBF between the 2 groups persisted after accounting for age, gender, body surface area, LVEF, and thigh muscle area (p <or= 0.03).
During CMR submaximal bike exercise in the elderly with heart failure, mechanisms other than low cardiac output are responsible for reduced lower extremity blood flow.
Journal of Cardiovascular Magnetic Resonance 11/2009; 11:48. · 3.72 Impact Factor
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Ross Arena,
Jonathan Myers,
Joshua Abella,
Sherry Pinkstaff, Peter Brubaker,
Brian Moore,
Dalane Kitzman,
Mary Ann Peberdy,
Daniel Bensimhon,
Paul Chase,
Daniel Forman,
Erin West,
Marco Guazzi
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ABSTRACT: Several investigations have demonstrated that higher body weight, as assessed by the body mass index, is associated with improved prognosis in patients with heart failure (HF). The purpose of the present investigation was to assess the influence of HF etiology on the prognostic ability of the body mass index in a cohort undergoing cardiopulmonary exercise testing. A total of 1,160 subjects were included in the analysis. All subjects underwent cardiopulmonary exercise testing, at which the minute ventilation/carbon dioxide production slope and peak oxygen consumption were determined. In the overall group, 193 cardiac deaths occurred during a mean follow-up of 30.7 +/- 25.6 months (annual event rate 6.0%). The subjects classified as obese consistently had improved survival compared to those classified as normal weight (overall survival rate 88.0% vs <or=81.1%, p <0.001). Differences in survival according to HF etiology were observed for those classified as overweight. In the ischemic subgroup, the survival characteristics for the overweight subjects (75.5%) were similar those for subjects classified as normal weight (81.1%). The converse was true for the nonischemic subgroup, for whom the survival trends for the obese (86.4%) and overweight subjects (88.4%) were similar. The minute ventilation/carbon dioxide production slope was the strongest prognostic marker (chi-square >or=43.4, p <0.001) for both etiologies, and the body mass index added prognostic value (residual chi-square >or=4.7, p <0.05). In conclusion, these results further support the notion that obesity confers improved prognosis in patients with HF, irrespective of the HF etiology. Moreover, the body mass index appears to add predictive value during the cardiopulmonary exercise testing assessment. However, survival appears to differ according to HF etiology in subjects classified as overweight.
The American journal of cardiology 10/2009; 104(8):1116-21. · 3.58 Impact Factor
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Ricardo B Oliveira,
Jonathan Myers,
Claudio Gil S Araújo,
Ross Arena,
Sandra Mandic,
Daniel Bensimhon,
Joshua Abella,
Paul Chase,
Marco Guazzi, Peter Brubaker,
Brian Moore,
Dalane Kitzman,
Mary Ann Peberdy
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ABSTRACT: There is scarce information regarding the prognostic utility of peak exercise oxygen pulse (peak O(2) pulse), a surrogate for stroke volume, in patients with heart failure (HF). From May 1994 to November 2007, 998 patients with HF underwent cardiopulmonary exercise testing. The ability of peak oxygen uptake (VO(2)) and peak O(2) pulse to predict cardiac events was examined. Peak O(2) pulse was calculated by dividing peak VO(2) by heart rate at the time peak VO(2) was achieved and was expressed in both milliliters per beat and as a percentage achieved of the age-predicted value. There were 212 cardiac events (176 deaths, 26 transplantations, and 10 left ventricular assist device implantations) over a mean of 28 +/- 26 months of follow-up. Peak VO(2) and age-predicted peak O(2) pulse were demonstrated by univariate and multivariate Cox regression analyses to be independent predictors of mortality (p <0.001). The optimal cut points for peak VO(2) and age-predicted peak O(2) pulse (<14.3 and > or =14.3 [mL/kg(-1)/min(-1)] and <85% and > or =85%, respectively) were established by areas under the receiver-operating characteristic curves. Patients exhibiting abnormalities for both responses had 4.8-fold (95% confidence interval 2.7 to 8.5) and 6.7-fold (95% confidence interval 4.1 to 11.1) higher risks for mortality and cardiac events, respectively, than those whose responses were normal. Age-predicted peak O(2) pulse also predicted mortality in patients in the intermediate range of peak VO(2) (10 to 14 (mL/kg(-1)/min(-1))). The 3-year mortality rate for patients in this range who had age-predicted peak O(2) pulse values <85% was even slightly higher than those with peak VO(2) <10.1 (mL/kg(-1)/min(-1)). In conclusion, age-predicted peak O(2) pulse was a strong and independent predictor of cardiac mortality and complemented peak VO(2) in predicting risk in patients with HF.
The American journal of cardiology 08/2009; 104(4):554-8. · 3.58 Impact Factor
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Ross Arena,
Jonathan Myers,
Joshua Abella,
Sherry Pinkstaff, Peter Brubaker,
Brian Moore,
Dalane Kitzman,
Mary Ann Peberdy,
Daniel Bensimhon,
Paul Chase,
Daniel Forman,
Erin West,
Marco Guazzi
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ABSTRACT: Peak oxygen consumption (Vo(2)) is routinely assessed in patients with heart failure undergoing cardiopulmonary exercise testing. The purpose of the present investigation was to determine the prognostic ability of several established peak Vo(2) prediction equations in a large heart failure cohort.
One thousand one hundred sixty-five subjects (70% males; age, 57.0+/-13.8 years; ischemic etiology, 43%) diagnosed with heart failure underwent cardiopulmonary exercise testing. Percent-predicted peak Vo(2) was calculated according to normative values proposed by Wasserman and Hansen (equation), Jones et al (equation), the Cooper Clinic (below low fitness threshold), a Veteran's Administration male referral data set (4 equations), and the St James Take Heart Project for women (equation). The prognostic significance of percent-predicted Vo(2) values derived from the 2 latter, sex-specific equations were assessed collectively. There were 179 major cardiac events (117 deaths, 44 heart transplantations, and 18 left ventricular assist device implantations) during the 2-year tracking period (annual event rate, 10%). Measured peak Vo(2) and all percent-predicted peak Vo(2) calculations were significant univariate predictors of adverse events (chi(2)> or =31.9, P<0.001) and added prognostic value to ventilatory efficiency (VE/Vco(2) slope), the strongest cardiopulmonary exercise testing predictor of adverse events (chi(2)=150.7, P<0.001), in a multivariate regression. The Wasserman/Hansen prediction equation provided optimal prognostic information.
Actual peak Vo(2) and the percent-predicted models included in this analysis all were significant predictors of adverse events. It seems that the percent-predicted peak Vo(2) value derived from the Wasserman/Hansen equations may outperform other expressions of this cardiopulmonary exercise testing variable.
Circulation Heart Failure 03/2009; 2(2):113-20. · 6.29 Impact Factor
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ABSTRACT: The oxygen uptake efficiency slope (OUES) response has not been characterized in heart failure (HF) patients with a normal ejection fraction (NEF). Fifty-nine subjects with systolic HF, 59 with HF-NEF and 28 healthy age-matched controls participated in this analysis. The OUES (systolic HF: 1.23+/-0.41 vs. HF-NEF: 1.22+/-0.30 vs. controls: 1.51+/-0.49) was significantly reduced in both HF groups compared to controls (p<0.001). Compared to healthy controls, the OUES is reduced in HF-NEF patients to a similar degree as those with systolic HF. Thus, as in systolic HF, the OUES may provide clinically useful information in patients with HF-NEF.
International journal of cardiology 02/2009; 144(1):101-2. · 7.08 Impact Factor
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Ross Arena,
Jonathan Myers,
Joshua Abella,
Sherry Pinkstaff, Peter Brubaker,
Brian Moore,
Dalane Kitzman,
Mary Ann Peberdy,
Daniel Bensimhon,
Paul Chase,
Marco Guazzi
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ABSTRACT: The resting partial pressure of end-tidal carbon dioxide (Petco2) has been shown to reflect cardiac performance in acute care settings in patients with heart failure (HF). The purpose of the present study was to compare the prognostic ability of the partial pressure of Petco2 at rest to other commonly collected resting variables in patients with systolic HF.
A total of 353 patients (mean age 58.6+/-13.7, 72% male) with systolic HF were included in this study. All patients underwent cardiopulmonary exercise testing where New York Heart Association (NYHA) class, resting Petco2, peak oxygen consumption, and the minute ventilation/carbon dioxide production slope were determined. Subjects were then followed for major cardiac events (mortality, left ventricular assist device implantation implantation, urgent heart transplantation).
There were 104 major cardiac events during the 23.6+/-17.0-month tracking period. Multivariate Cox regression analysis revealed NYHA class (chi2 28.7, P<.001), left ventricular ejection fraction (residual chi2 21.7, P<.001), and resting Petco2 (residual chi2 14.1, P<.001) were all prognostically significant and retained in the regression. In a separate Cox regression analysis, left ventricular ejection fraction (residual chi2 8.8, P=.003), NYHA class (residual chi2 7.7, P=.005), and resting Petco2 (residual chi2 5.7, P=.02) added prognostic value to the minute ventilation/carbon dioxide production slope (chi2 26.0, P<.001).
Resting Petco2 can be noninvasively collected from subjects in a short period, at a low cost, and with no risk or discomfort to the patient. Given the prognostic value demonstrated in the present study, the clinical assessment of resting Petco2 in the HF population may be warranted.
American heart journal 12/2008; 156(5):982-8. · 4.65 Impact Factor
