FRIEND Registry Research Articles

What is the true normal: comparison of different equations for estimating peak oxygen uptake for outcome prediction in heart failure

Abstract Background and Objectives One of the strongest prognostic parameters obtained during Cardiopulmonary exercise testing (CPET) in patients with heart failure (HF) is the peak oxygen uptake (pVO2), as a standalone or as a percentage of the predicted peak oxygen uptake (ppVO2) reached. However, traditional standards by which ppVO2 is calculated have limitations, having been derived from small cohorts, lacking portability and poorly represented by women. Thus, we aim to compare the FRIEND Registry equation to previously used methods of calculating ppVO2 as it relates to prognostic value imparted by the percentage of ppVO2 (%ppVO2) reached during CPET and portability to the Portuguese HF population. Methods Single centre retrospective study of patients with HF with LVEF < 50% who underwent CPET between 2015-2021. Patients who did not reach RER≥ 1.05 were excluded from our analysis. All tests were evaluated and ventilatory thresholds determined by 3 independent, experienced operators. ppVO2 was calculated according to 1) the Wasserman equation; 2) the Wasserman equation using ideal body weight; 3) the Neder equation, 4) the SHIP equation and 5) the FRIEND equation. Our primary endpoint was a composite of CV death, urgent transplant or left ventricular assist device implantation and HF hospitalization. Results We included 238 patients (mean age 59 ± 11 years, 83% males). The HF aetiology was mostly ischemic in nature (68%), with LVEF of 34 ± 9% and median NTproBNP of 776 (2566 – 2342) pg/mL. Most patients (67%) were in class NYHA I-II and with high prevalence of GDMT (93% ACEi/ARB; 97% beta-blockers and 64% on MRA). Mean BMI in this group was 27.3 ± 4.7 kg/min. Patients performed CPET on a treadmill with a protocol adjusted to their predicted exercise capacity. Mean pVO2 was 18.1 ± 6.2mL/kg/min, corresponding to a median %ppVO2 that ranges from 51 ± 16% to 71 ± 22%, depending on the equation that is used. Mean VE/VCO2 Slope was 42 ± 13 and 48 % (n = 98) of patients showed exercise oscillatory ventilation (EOV). Mean ppVO2 as per the FRIEND and Wasserman equations was 18.9 ± 6.6 and 21.2 ± 4.5 mL/kg/min, with no statistically significant difference between both. %ppVO2 as calculated through all equations was an independent predictor of prognosis on multivariate analysis adjusted for LVEF, NTproBNP and VE/VCO2 Slope (p < 0.001 for values derived from all equations). However, the FRIEND and Wasserman equations showed a slight advantage over the remaining 2 equations, with higher AUC on ROC curve analysis (see figure). Conclusions In our population of Portuguese patients with HF, both the FRIEND registry and Wasserman equations for predicting pVO2 yielded strong prognostic power. However, these equations provide different absolute predicted VO2 values for the same patients and thus should not be used interchangeably. Standardisation of the type ppVO2 equation used should be recommended by local scientific societies.

Peak oxygen pulse response during maximal cardiopulmonary exercise testing on a treadmill: applicability analysis of the FRIEND registry prediction equation in a Brazilian healthy sample

Abstract Background Peak oxygen uptake (VO2peak), measured by cardiopulmonary exercise test (CPET), is an established variable for prognostic assessment. Other VO2peak-derived variables, such as the peak oxygen pulse (peakO2pulse), also provide valuable information for risk stratification in patients with cardiac diseases. For individualized assessment, the measured peakO2pulse can be compared to reference standards using predictive equations, such as the FRIEND Registry [peakO2pulse = 23.2 – (0.09 × Age) – (6.6 × Sex (female:1; male: 0)]. However, the applicabilty of this equation in a Brazilian population sample has never been evaluated. Purpose To conduct an external validation of the FRIEND registry prediction equation for treadmill peakO2pulse in a sample of healthy Brazilian individuals. Methods Cross-sectional study involving subjects assessed by treadmill CPET in the Brazilian Midwest region from January 2011 to March 2020. Inclusion criteria: healthy individuals aged ≥ 20 years with a peak respiratory exchange ratio ≥ 1.00. Exclusion criteria: history of cardiovascular or pulmonary disease, presence of cardiovascular risk factors (hypertension, diabetes mellitus, current smoking, and obesity), and abnormalities on CPET. Variables were described as median and interquartile range (IQR). Statistical comparisons between measured and predicted values were conducted using the Wilcoxon signed rank test, including the calculation of the median differences and the 95% confidence interval (CI). Furthermore, Bland-Altman agreement analysis was utilized to assess the concordance between measured and estimated values. Results A total of 7,843 CPETs were performed. After applying inclusion and exclusion criteria, 3,544 assessments were included (1,574 females and 1,970 males) aged between 20 to 80 years. In the females, the median and IQR of measured peakO2pulse and predicted values were 10.4 (9.0; 12.1) and 13.1 (12.3; 13.7) ml/beat, respectively. This difference was statistically significant (p < 0.001), with a median difference of 2.54 mL/beat (95% CI: 2.40; 2.69). For males, the measured and predicted values were 17.3 (15.1; 19.7) and 19.7 (19.0; 20.2) ml/beat, respectively. The median difference was statistically significant at 2.26 mL/beat (95% CI: 2.11; 2.46) (p < 0.001) (Figure 1). Bland-Altman agreement analysis indicated a bias of 2.33 mL/beat (95% limits of agreement: -2.17 to 6.83) in females and 2.15 mL/beat (95% limits of agreement: -4.34 to 8.65) in males (Figure 2). Conclusions The study reveals that measured median peakO2pulse values are consistently lower than predicted across both sexes, highlighting a significant bias, which limits the applicability of the FRIEND registry prediction equation in the Brazilian population and underscores the international heterogeneity of the variable. The findings advocate for the development of region-specific reference standards to enhance accuracy in predicting peakO2pulse values.

Peak oxygen uptake during treadmill cardiopulmonary exercise testing: applicability analysis of the FRIEND registry prediction equation in a Brazilian healthy sample

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES). Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). Background Peak oxygen uptake (VO2peak) measured by cardiopulmonary exercise testing (CPET) is an important marker for health, physical performance and cardiovascular prognosis. Measured values are compared to reference standards for an adequate individual assessment. However, regional and international heterogeneities for VO2peak values have already been demonstrated by Milani, which may limit the external validation of the predictive equations developed in different nationalities. One of these equations was developed in an American population sample (FRIEND Registry) by Myers, but this equation has never been evaluated for portability in a population sample from the Brazilian Midwest region. Purpose To analyze the applicability of the FRIEND registry prediction equation for treadmill VO2peak in a healthy Brazilian sample from the Midwest region. Methods Cross-sectional study of subjects assessed by CPET in the Brazilian Midwest region between January/2011 to March/2020. The inclusion criteria were CPET performed on a treadmill in healthy subjects aged 20 years or older, and with respiratory exchange ratio ≥ 1.0. The exclusion criteria were any history of cardiovascular or pulmonary disease, presence of cardiovascular risk factors (such as hypertension, diabetes mellitus, current smoking, and obesity) and abnormalities on CPET. Variables were described as median and interquartile range. Statistical comparisons between measured and predicted VO2peak were performed using Spearman correlation test, Wilcoxon signed rank test, and Bland-Altman agreement analysis. Results During the study period, 7,843 CPET were performed and included for eligibility. After applying the inclusion and exclusion criteria, 3,544 assessments of healthy individuals were included (1,574 women; 1,970 men; age 20 to 80 years). The measured and predicted VO2peak were, respectively, 29.4 (25.1; 33.9) and 33.1 (29.5; 36.2) mL/kg/min in females, and 39.4 (34.3; 43.9) and 42.2 (39.1; 45.0) mL/kg/min in males, with significant differences (p < 0.0001). Correlations were significant (p < 0.0001) for both sexes (rho = 0.418 in women and 0.432 in men) (Figure 1). The mean error by the Bland-Altman agreement analysis was similar in both sexes, with a bias of -2.96 mL/kg/min (95% limits of agreement: -14.96 to 9.04 ) in females and a bias of -2.78 mL/kg/min (95% limits of agreement: - 15.39 to 9.83) in males (Figure 2). Conclusions The median values of the measured VO2peak were lower than the predicted values for both sexes, with a significant mean error, which limits the applicability of the FRIEND registry prediction equation in the Brazilian Midwest region population and highlights the international heterogeneity of the variable.

Peak ventilation during treadmill cardiopulmonary exercise testing: applicability analysis of the FRIEND registry prediction equation in a Brazilian healthy sample

Abstract Background Peak ventilation (VEpeak) measured by cardiopulmonary exercise testing (CPX) is a valuable clinical information, especially in patients with pulmonary diseases. Measured values can be compared to maximal voluntary ventilation or to predicted VEpeak calculated by nonexercise equations. However, the FRIEND Registry prediction equation has never been assessed for portability in a Brazilian population sample. Purpose To analyze the applicability of the FRIEND registry prediction equation for VEpeak during treadmill CPX in a Brazilian healthy sample. Methods Cross-sectional study of subjects assessed by CPX in the Brazilian Midwest region between January/2011 to March/2020. The inclusion criteria were CPX performed on treadmill in healthy individuals aged 20 years or older, and with respiratory exchange ratio ≥1.0. The exclusion criteria were any history of cardiovascular or pulmonary disease, presence of cardiovascular risk factors (such as hypertension, diabetes mellitus, current smoking, and obesity) and abnormalities on CPX. Measured VEpeak values were compared with predicted values calculated using age, sex, and height, according to the FRIEND Registry prediction equation. Variables were described as median and interquartile range. Statistical comparisons between measured and predicted VEpeak were performed using Spearman correlation test, Wilcoxon signed rank test, and Blant-Altman agreement analysis. Results During the study period 7,843 CPX were performed and included for study eligibility. After the inclusion and exclusion criteria were applied, 3,544 healthy individuals' assessments were included [1,574 females and 1,970 males, age 39 (33, 47) years]. The measured and predicted VEpeak were, respectively, 76.8 (66.7, 87.4) and 76.2 (68.5, 83.0) L min–1 in females, with significant difference (p=0.004). In males, the measured and predicted VEpeak were, respectively, 123.0 (107.3, 137.3) and 114.8 (107.5, 120.7) L min–1, also with statistical difference (p<0.001). Correlations were significant (p<0.001) for both sexes (r2=0.424 for females and .421 for males) (Figure 1). Average error was lower for females than males, with bias of 1.22 L min–1 (95% limits of agreement: - 26.95 to 29.39) in females and bias of 8.41 L min–1 (95% limits of agreement: −33.04 to 49.87) in males (Figure 2). Conclusion Measured VEpeak median values were greater than predicted median values for both sexes, with lower average error in females than in males. The significant average error in males limits the prediction equation applicability in the Brazilian population. Thus, the development of a new Brazilian prediction equation is necessary to better evaluate the variable response during CPX in Brazil. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).

Peak Circulatory Power during Maximal Cardiopulmonary Exercise Testing: Reference Standards from the FRIEND Registry.

Normative standards for key cardiopulmonary exercise (CPX) test variables, including peak circulatory power (CircP), are needed to guide the interpretation of clinical exercise responses in individuals with and without disease. This study aimed to establish age- and sex-specific reference standards for peak CircP derived from a healthy cohort from the Fitness Registry and the Importance of Exercise: A National Database (FRIEND). CPX test data from apparently healthy males and females from eight FRIEND United States exercise laboratories were considered. Inclusion criteria included ages 20-79 yr and a maximal, symptom-limited exercise test performed on a treadmill or cycle ergometer. CircP was calculated as the product of peak oxygen consumption and peak systolic blood pressure. Reference values were determined on both treadmill and cycle ergometer for males and females per age decade. A stepwise linear regression to predict CircP was derived from two-thirds of the sample while the remaining one-third was used as a validation cohort. A total of 6736 CPX tests (47% treadmill, 53% female) were included in the analysis. Overall, CircP was higher in males, higher on tests conducted on a treadmill, and decreased with age. Sex, exercise mode, age, and body mass index were the most significant contributors to CircP (multiple R = 0.75, R2 = 0.57, root-mean-square error = 1200 mm Hg·mL O 2 ·kg -1 ·min -1 , P < 0.001). Using the generated prediction equation, the average percent-predicted CircP for the validation cohort was 101.3% ± 28.1%. These results establish reference standards for CircP, a potentially important prognostic indicator of cardiovascular health. Future research exploring the role of percentiles and percent-predicted values for CircP is necessary as they may provide additional prognostic insight.

Comparing individual and population differences in minute ventilation/carbon dioxide production slopes using centile growth curves and log-linear allometry.

Identifying vulnerable groups and/or individuals’ cardiorespiratory fitness (CRF) is an important challenge for clinicians/researchers alike. To quantify CRF accurately, the assessment of several variables is now standard practice including maximal oxygen uptake (VʹCO2) and ventilatory efficiency, the latter assessed using the minute ventilation/carbon dioxide production (VʹE/VʹCO2) slope. Recently, reference values (centiles) for VʹE/VʹCO2 slopes for males and females aged 20 to 80 have been published, using cardiopulmonary exercise testing (CPX) data (treadmill protocol) from the Fitness Registry and the Importance of Exercise National Database (FRIEND Registry).In the current observational study we provide centile curves for the FRIEND Registry VʹE/VʹCO2 slopes, fitted using the generalised additive model for location, scale and shape (GAMLSS), to provide individuals with a more precise estimate of where their VʹE/VʹCO2 slopes fall within the population. We also confirm that by adopting allometric models (incorporating a log transformation), the resulting ANCOVAs provided more normal and homoscedastic residuals, with superior goodness-of-fit using the Akaike information criterion (AIC)=14 671 (compared with traditional ANCOVA's AIC=15 008) that confirms allometric models are vastly superior to traditional ANCOVA models.In conclusion, providing sex-by-age centile curves rather than referring to reference tables for ventilatory efficiency (VʹE/VʹCO2 slopes) will provide more accurate estimates of where an individual's particular VʹE/VʹCO2 slope falls within the population. Also, by adopting allometric models researchers are more likely to identify real and valid inferences when analysing population/group differences in VʹE/VʹCO2 slopes.

Edmonton Obesity Staging System: an improvement by cardiopulmonary exercise testing.

Different approaches are used to classify obesity severity. Beyond classical anthropometric measurements, the Edmonton Obesity Staging System (EOSS) considers medical, physical and psychological parameters. However, this method has some limitations, principally due to the absence of an objective measure for physical impairment. The aim of our study is thus to overcome this limitation suggesting a new functional parameter obtained by cardiopulmonary exercise testing (CPET), i.e., cardiorespiratory fitness (CRF), expressed as weight-adjusted peak oxygen consumption (VO2peak/kg). This observational cross-sectional study conducted on a population of 843 patients affected by obesity finally enrolled 500 subjects. Every patient underwent clinical, anthropometric, biochemical assessment and CPET. First, participants have been classified according to standard EOSS in five stages. Second, patients were reclassified according to the new modified EOSS (EOSS-CRF) based on their age- and gender-appropriate VO2peak/kg percentiles as reported in the healthy normal-weight population of the FRIEND registry. VO2peak/kg was significantly different between standard EOSS classes 1 and 2 and classes 1 and 3 (ANCOVA p model = 0.004), whereas patients in classes 2 and 3 showed similar CRF. The EOSS-CRF classification varied in number of patients in each class compared to EOSS, particularly with a shift from class 2 to class 3. Moreover, CRF showed that physical impairment is less addressed by EOSS when compared to EOSS-CRF. The integration of EOSS with CRF allowed us to assign to each patient a severity index that considers not only clinical parameters, but also their functional impairment through a quantitative and prognostically important parameter (VO2peak/kg). This improvement of the staging system may also provide a better approach to identify individuals at increased risk of mortality leading to targeted therapeutic management and prognostic risk stratification for patients with obesity.

Abstract 15016: Peak Oxygen Consumption Achieved at the End of Cardiac Rehabilitation Predicts Survival in Patients With Coronary Heart Disease

Introduction: Several patients with coronary heart disease (CHD) present reduced survival despite completing cardiac rehabilitation (CR), suggesting that the level of cardiorespiratory fitness (CRF) achieved might remain suboptimal. The purposes of this study were: 1) to examine the independent association of peak oxygen consumption (VO 2 ), a measure of CRF, at post-CR with long-term survival; and 2) to establish an optimal cut-off for peak VO 2 at post-CR that best predicts mortality risk. Methods: 853 patients with CHD (mean age of 64±10 years old) who were referred to CR between January 1, 2000, and June 30, 2013, at Ochsner Medical Center were analyzed for this study. We measured pre- and post-CR peak VO 2 . Mortality data were collected using National Death Index. Cox proportional hazard regression model was used to examine the risk of all-cause mortality associated with peak VO 2 at post-CR, independent of peak VO 2 at pre-CR and related changes during CR. Contal and O’Quigley’s method were used to determine the optimal cut-off for peak VO 2 at post-CR based on a split-sample approach. Results: Mean peak VO 2 at post-CR was 21.01±6.25 mL/kg/min (75% and 51% predicted peak VO2 using Wasserman and FRIEND Registry equations, respectively). During a mean follow-up of 6.55 years, 106 subjects (12.4%) died. Peak VO 2 at post-CR independently predicted mortality (Hazard Ratio: 0.82 [0.77-0.87], p&lt;0.001). We identified peak VO 2 of ≥17.6 kg/mL/min as optimal cut-off best predicting survival ( Figure 1, Panel A ) and the %predicted peak VO2 at post-CR ≥62.1% using Wasserman ( Figure 1, Panel B ) and ≥41.4% using FRIEND Registry ( Figure 1, Panel C ) as the alternative optimal cut-offs. Conclusions: In patients with CHD undergoing CR, post-CR peak VO 2 independently predicts long-term survival. These results suggest that patients with CHD presenting a peak VO 2 lower than the cut-off identified herein may benefit from additional sessions of CR or higher intensity exercise training.

VO2max-Based Physical Fitness Categories in a Brazilian Population with Supposed High Socioeconomic Status and without Structural Heart Disease.

ResumoFundamento Os dados mais utilizados como referência de aptidão cardiorrespiratória (ACR) são os de Cooper, que utiliza valores calculados de captação máxima de oxigênio (VO2máx).Objetivo Desenvolver valores de ACR a partir do teste cardiopulmonar de exercício (TCPE) em uma população brasileira com alto nível socioeconômico e livre de cardiopatia estrutural. Os resultados dos testes de VO2max foram comparados aos dados de Cooper e do FRIEND Registry.Métodos Foram utilizados neste estudo dados de TCPE de indivíduos consecutivos entre 1º de janeiro de 2000 e 31 de maio de 2016. Os critérios de inclusão foram: VO2máx pré-definido. Foi construído um gráfico de ACR de acordo com os percentuais do VO2máx: muito ruim (≤20%), ruim (20-40%), regular (40-60%), boa (60-80%), excelente (80-90%), e superior (≥90%). A correlação Kappa foi usada para analisar nossos dados em comparação aos dados dos outros dois bancos de dados. Os testes estatísticos com p<0,005 foram considerados significativos.Resultados A coorte final incluiu 18.186 testes: 12.552 homens, 5.634 mulheres (7 a 84 anos). A resposta mais recorrente foi “boa” (20,2%). Houve diferença média de peso, altura, índice de massa corporal (IMC) e idade no gráfico da ACR. Houve correlação inversa entre VO2máx e idade, peso e IMC. Usando uma regressão linear e essas variáveis, uma equação preditiva foi desenvolvida para o VO2máx. Nossas descobertas diferiram das dos outros bancos de dados.Conclusão Desenvolvemos uma classificação para a ACR e encontramos valores mais altos em todas as faixas de classificação de capacidade funcional, em contraste com os dados de Cooper e do FRIEND Registry. Nossos achados oferecem uma interpretação mais precisa da ACR nessa grande amostra populacional brasileira, quando comparados aos padrões anteriores, com base no VO2máx estimado. (Arq Bras Cardiol. 2020; 115(3):468-477)

Is population's cardiorespiratory fitness really declining?

Cardiorespiratory fitness (CRF) is defined as the capacity of the cardiovascular and pulmonary systems to meet the oxygen demands of the body during physical work. Poor CRF is connected with a higher risk for the development of various noninfectious diseases such as cardiovascular disease or malignancies. The standard test for the assessment of CRF is exercise testing with the measurement of maximal oxygen consumption (VO2 max). Standard VO2 max values for adult men and women in the Czech Republic have been available since the 1970s without being updated. According to experts, these standard values are now unusable for contemporary CRF measurements of the population in the Czech Republic. The Fitness Registry and the Importance of Exercise: a National Database (FRIEND) - 4,494 patients (1,717 men) defined new standard values for bicycle ergometry CRF for the population in the United States of America. The aim of the study was the statistical comparison of VO2 max values (reference standards) in the 1970s population in the Czech Republic with the new reference standards of the FRIEND registry. All analyses were performed using IBM SPSS statistics and all tests with a p-value of less than 0.05 were considered statistically significant. VO2 max norms for women in the Czech population were higher in all age categories with statistically significant differences in the categories 30-39, 40-49 and 50-59 (p < 0.001). In the male population aged 20-29 years, VO2 max was significantly higher in the FRIEND registry (p < 0.001) in contrast to the other age categories, 30-39, 40-49 and 50-59, which were significantly higher in the Czech population (p < 0.001). Czech VO2 max population norms from the 1970s are (with the exception of age category 20-29 years) higher than values from the recent FRIEND registry.

Peak Ventilation Reference Standards from Exercise Testing: From the FRIEND Registry-Corrigendum.

Peak Ventilation Reference Standards from Exercise Testing: From the FRIEND Registry-Corrigendum.

Improved percent-predicted peak VO2 is associated with lower risk of hospitalization in patients with coronary heart disease. Analysis from the FRIEND registry

BackgroundNormal standards for peak oxygen consumption (VO2peak) are controversial because they tend to be population and protocol specific. This study was undertaken to examine the association between percentage of age-predicted VO2peak and all-cause hospital readmission in cardiac outpatients who were referred to an exercise-based secondary prevention program. MethodsHospital readmission was assessed in 1283 male patients with coronary heart disease (CHD) three years after enrolment, and related to the age-predicted VO2peak derived from the Fitness Registry and the Importance of Exercise: A National Data Base equation (FRIEND%PRED). VO2peak was estimated using a moderate perceptually regulated 1-km treadmill-walking test. Readmission was also assessed during the fourth-to-sixth years as function of improvement in FRIEND%PRED in 845 patients who were re-evaluated 3 years after baseline. ResultsDuring the 3-years after baseline, readmission rate was lower across increasing tertiles of FRIEND%PRED. Compared to the lowest tertile, the adjusted hazard ratios (HRs) for the second and third tertile were 0.98 (95% CI 0.76–1.27, p = 0.90) and 0.71 (0.53–0.95, p = 0.002). The rate of readmission from the fourth-to-sixth years after baseline was lower across tertiles of improved FRIEND%PRED, with adjusted HRs 0.78 (0.60–1.03, p = 0.08) and 0.58 (0.42–0.75, p < 0.0001) for the intermediate and high tertiles vs the lowest tertile. After adjustment for confounders, every 1 unit % increase in FRIEND%PRED was associated with a 3% reduction in risk of readmission (HR 0.97, 0.95–0.98, p < 0.0001). ConclusionsAge-predicted VO2peak estimated by a moderate treadmill-walk predicts hospital readmission in outpatients with CHD undergoing secondary prevention.

Peak Ventilation Reference Standards from Exercise Testing: From the FRIEND Registry

Cardiopulmonary exercise testing (CPX) provides valuable clinical information, including peak ventilation (V˙Epeak), which has been shown to have diagnostic and prognostic value in the assessment of patients with underlying pulmonary disease. This report provides reference standards for V˙Epeak derived from CPX on treadmills in apparently healthy individuals. Nine laboratories in the United States experienced in CPX administration with established quality control procedures contributed to the Fitness Registry and the Importance of Exercise National Database from 2014 to 2017. Data from 5232 maximal exercise tests from men and women without cardiovascular or pulmonary disease were used to create percentiles of V˙Epeak for both men and women by decade between 20 and 79 yr. Additionally, prediction equations were developed for V˙Epeak using descriptive information. V˙Epeak was found to be significantly different between men and women and across age groups (P < 0.05). The rate of decline in V˙Epeak was 8.0% per decade for both men and women. A stepwise regression model of 70% of the sample revealed that sex, age, and height were significant predictors of V˙Epeak. The equation was cross-validated with data from the remaining 30% of the sample with a final equation developed from the full sample (r = 0.73). Additionally, a linear regression model revealed forced expiratory volume in 1 s significantly predicted V˙Epeak (r = 0.73). Reference standards were developed for V˙Epeak for the United States population. Cardiopulmonary exercise testing laboratories will be able to provide interpretation of V˙Epeak from these age and sex-specific percentile reference values or alternatively can use these nonexercise prediction equations incorporating sex, age, and height or with a single predictor of forced expiratory volume in 1 s.

A reference equation for maximal aerobic power for treadmill and cycle ergometer exercise testing: Analysis from the FRIEND registry.

Background Maximal oxygen uptake (VO2max) is a powerful predictor of health outcomes. Valid and portable reference values are integral to interpreting measured VO2max; however, available reference standards lack validation and are specific to exercise mode. This study was undertaken to develop and validate a single equation for normal standards for VO2max for the treadmill or cycle ergometer in men and women. Methods Healthy individuals ( N = 10,881; 67.8% men, 20-85 years) who performed a maximal cardiopulmonary exercise test on either a treadmill or a cycle ergometer were studied. Of these, 7617 and 3264 individuals were randomly selected for development and validation of the equation, respectively. A Brazilian sample (1619 individuals) constituted a second validation cohort. The prediction equation was determined using multiple regression analysis, and comparisons were made with the widely-used Wasserman and European equations. Results Age, sex, weight, height and exercise mode were significant predictors of VO2max. The regression equation was: VO2max (ml kg-1 min-1) = 45.2 - 0.35*Age - 10.9*Sex (male = 1; female = 2) - 0.15*Weight (pounds) + 0.68*Height (inches) - 0.46*Exercise Mode (treadmill = 1; bike = 2) ( R = 0.79, R2 = 0.62, standard error of the estimate = 6.6 ml kg-1 min-1). Percentage predicted VO2max for the US and Brazilian validation cohorts were 102.8% and 95.8%, respectively. The new equation performed better than traditional equations, particularly among women and individuals ≥60 years old. Conclusion A combined equation was developed for normal standards for VO2max for different exercise modes derived from a US national registry. The equation provided a lower average error between measured and predicted VO2max than traditional equations even when applied to an independent cohort. Additional studies are needed to determine its portability.

The Role of Body Habitus in Predicting Cardiorespiratory Fitness: The FRIEND Registry.

This study aimed to validate and cross-validate a non-exercise prediction model from a large and apparently healthy US cohort of individuals who underwent an analysis of body habitus (waist circumference (WC) and body mass index (BMI)) with measured CRF. The large cohort (5 030 individuals) was split into validation (4 030) and cross-validation (1 000) groups, whereby waist circumference and maximal aerobic capacity (VO2max) were assessed by rigorously approved laboratories. VO2max was estimated in 2 multiple regression equations using age, sex and either WC (r=0.77; standard error of the estimate (SEE) 6.70 mLO2∙kg(-1)∙min(-1)) or BMI (r=0.76; SEE 6.89 mLO2∙kg(-1)∙min(-1)).Cross-validation yielded similar results. However, as VO2max increased, there was increased bias, suggesting VO2max may be underestimated at higher values. Both WC and BMI prediction models yielded similar findings, with WC having a slightly smaller SEE. These measures of body habitus appear to be adequate in predicting CRF using non-exercise parameters, even without a measure of physical activity. Caution should be taken when using these equations in more fit individuals.

The Role of Body Habitus in Predicting Cardiorespiratory Fitness: Findings from the FRIEND Registry

Body habitus has been previously reported to be important in the development of non‐exercise prediction models for estimating cardiorespiratory fitness (CRF). Yet, these previous models have included indices of physical activity, which is not widely assessed in the clinical setting.PurposeTo validate and cross‐validate a non‐exercise prediction model from a large and apparently healthy U.S. cohort of individuals who underwent an analysis of body habitus (waist circumference (WC) and body mass index (BMI)) with measured CRF.MethodsThe large cohort (5030 individuals) was split into validation (4030) and cross‐validation groups (1000), whereby waist circumference and maximal aerobic capacity (VO2max) were assessed by rigorously approved laboratories.ResultsVO2max was estimated in 2 multiple regression equations using age, sex, and either WC (r = 0.77; standard error of the estimate (SEE) 6.70 mLO2 ·kg−1·min−1) or BMI (r = 0.76; SEE 6.89 mLO2 ·kg−1·min−1). Cross‐validation yielded similar results. However, as VO2max increased, there was increased bias, suggesting VO2max may be underestimated at higher values.ConclusionsBoth WC and BMI prediction models yielded similar findings, with WC having a slightly smaller SEE. These measures of body habitus appear to be adequate in predicting CRF using non‐exercise parameters, even without a measure of physical activity. Caution should be taken when using these equations in higher fit individuals.Support or Funding InformationTKC Global Solutions, LLC.

Revisiting age-predicted maximal heart rate: Can it be used as a valid measure of effort?

Despite high error ranges, age-predicted maximal heart rate (APMHR) is frequently used to gauge the achievement of adequate effort during an exercise test. The current analysis revisits this issue using the Fitness Registry and the Importance of Exercise: National Database (FRIEND Registry). A total of 4,796 (63% male) apparently healthy subjects underwent a maximal cardiopulmonary exercise test on a treadmill. The mean age, maximal heart rate (HR), and maximal aerobic capacity of the cohort were 43 ± 12 years, 178 ± 15 beats per minute, and 36.1 ± 10.6 mlO2 · kg(-1) · min(-1), respectively. All subjects reached or surpassed a peak respiratory exchange ratio of 1.10. A linear regression equation using age to predict maximal HR was validated in 3,796 subjects and cross-validated in the remaining 1,000 (randomly assigned). The APMHR equation in the validation cohort was as follows: 209.3 - 0.72(age). The r value and standard error of estimate for this regression was 0.61 (P < .001) and 11.35 beats/min, respectively. A 1-sample t test revealed that the mean difference between actual maximal HR and APMHR was not significantly different from 0 (mean difference = 0.32, P = .43). However, Bland-Altman revealed high limits of agreement (upper 25.31 and lower -24.67) and a significant proportional bias. The APMHR equation derived from this analysis included a large cohort of apparently healthy individuals with maximal exercise effort validated by the criterion standard (ie, peak respiratory exchange ratio). Using APMHR in this capacity should be discouraged, and new approaches to gauging an individual's exercise effort should be explored.

032 Percutaneous treatment of unprotected left main coronary stenoses with paclitaxel-eluting stents. 3-year clinical follow-up of a French prospective multicenter study: Friend Registry

Percutaneous treatment of unprotected left main coronary artery (ULMCA) disease is progressively gaining acceptance in light of the first results from drug-eluting stent registries or randomized trial. We thus assessed early and mid-term results of patients treated for ULMCA disease in the FRIEND registry. After ethical committee approval and informed consent, all consecutive patients with unprotected left main stenoses treated with Taxus stents were included in a multicenter prospective study from 23 centers. Major adverse cardiac and cerebro-vascular events (MACCE) were adjudicated at 1,6,12,18 and 36 months by an independent committee. Immediate and 9-month angiographic results were assessed by a central core lab (Corysis, St-Denis, France). From December 2005 to July 2006, 151 patients (pts) were included, mean age 68 ± 11 years, 83% male, 41% unstable angina, 3% diabetics, 24% 3-vessel disease. The mean Euroscore was 4.1 ± 2.8. The LM reference diameter was 3.9 ± 0.5 mm. LM lesion was non distal in 34%, and distal in 66% of pts. In this group, 72% were located at the bifurcation including LAD, LCX or both ostia affected. All patients were successfully treated on the LM (stent length 15.7 ± 5.2 mm) and a final kissing balloon inflation was performed in 90%. Apart from the LM stenosis, a total of 1.2 ± 0.8 lesions were treated during the hospitalisation (total stent length 47 ± 16 mm). In-hospital MACCE rate was 4.5% with 2.6% of mortality; at 9-month follow-up (FU), the global rate of event-free survival was 93.5% with a very low angiographic restenosis rate of 3%. Between 9 and 36-month clinical FU, there were one sudden death, 6 extra-cardiac deaths (total mortality 7%), one recurrent angina and 1 cardiac failure. Event free survival was 84%. LM PCI using the TAXUS stent is feasible and safe at long-term follow-up. Stenting deserves to be considered a safe and effective alternative to CABG in institutions performing large numbers of PCIs.

TCT-147: Percutaneous Treatment Of Unprotected Left Main Coronary Stenoses With Paclitaxel-eluting Stents. 3-year Clinical Follow-up Of A French Prospective Multicenter Study: Friend Registry

TCT-147: Percutaneous Treatment Of Unprotected Left Main Coronary Stenoses With Paclitaxel-eluting Stents. 3-year Clinical Follow-up Of A French Prospective Multicenter Study: Friend Registry

Twelve month clinical and angiographic outcome after stenting of unprotected left main coronary artery stenosis with paclitaxel-eluting stents – results of the multicentre FRIEND registry

To evaluate the angiographic and clinical outcome of patients undergoing paclitaxel-eluting stent (PES) implantation for unprotected left main coronary artery (ULMCA) stenosis in a multicentre, prospective registry. The overall event rate for PCI of ULMCA disease remains higher than in on-label use making additional outcome data and risk-stratification tools for the ULMCA population desirable. A prospective registry included all patients with a significant (> 50%) stenosis in ULMCA disease. In 151 of these patients the target lesion involved the distal bifurcation in 100 patients (66%), which was treated by predominantly using a "provisional T stenting" strategy. In distal ULMCA disease group, 72% had only one stent implantation while 28% had multiple (either 2 or 3) stents implanted. At a median follow-up of 472 +/- 75 days, cardiac death occurred in 3 patients (2%) and major adverse cardiac and cerebrovascular events (MACCE) in 16 patients (10.6%). In the drug-eluting stent era, paclitaxel eluting stent implantation of ULMCA stenosis provided excellent immediate and mid-term results in this selected population, suggesting that it may be considered as a safe and effective alternative to CABG for selected patients with ULMCA who are treated in institutions performing large numbers of PCI procedures.