Importance of treadmill exercise time as an initial prognostic screening tool in patients with systolic left ventricular dysfunction

Monitoring the Effects of Cardiac Rehabilitation Programs in Heart Failure Patients: The Role of Biomarkers

Heart failure (HF) is characterized by poor exercise tolerance and reduced ability to perform routine daily activities. Cardiac rehabilitation (CR), which includes exercise training, has shown a role in improving cardiac remodeling, functional capacity and HF outcomes as a consequence of its beneficial effects on neurohormonal dysfunction, endothelial function, vascular tone and peripheral oxygen extraction. Although a multiparametric evaluation, including physical examination, blood sampling, echocardiographic and cardiopulmonary exercise testing parameters, is routinely performed during CR programs, the use of cardiac biomarkers, in particular natriuretic peptides (NPs), is still poorly adopted and characterized. In this article we analyze the potential role of biomarkers in monitoring the success of rehabilitation programs and the potential implications of their use in clinical practice. Indeed, NPs measurements might represent an important tool to modulate the rehabilitative interventions with a favorable cost-effectiveness profile.

Risk Stratification with Haemodynamic Gain Index and Peak Rate-Pressure Product in Patients with Chronic Heart Failure Undergoing Treadmill Exercise Testing

AIMS

We recently demonstrated the combined prognostic value of two simple non-invasive parameters obtained from treadmill exercise testing in patients with heart failure (HF) with reduced ejection fraction, the haemodynamic gain index (HGI) and peak rate-pressure product (RPP). However, their prognostic value is yet to be validated in patients with undifferentiated HF syndrome.

METHODS

We identified consecutive HF patients undergoing treadmill exercise testing for symptom evaluation between 1/1991-2/2015. HGI was calculated from [(SBPpeak x heart ratepeak) - (SBPrest x heart raterest)]/(SBPrest x heart raterest), and peak RPP was calculated from SBPpeak x heart ratepeak. Hazard ratios per doubling of HGI and peak RPP for all-cause mortality were estimated using multivariable Cox regression models with adjustment for traditional cardiovascular risk factors and exercise testing parameters (chronotropic reserve index, estimated metabolic equivalents, abnormal heart rate recovery, and total exercise time).

RESULTS

In our cohort of 5,940 patients with symptomatic HF diagnosis with median follow up of 7.1 years, 2,222 (37.4%) patients died. Higher both HGI and peak RPP were associated with a lower risk of mortality (adjusted hazard ratio per standard deviation increase 0.80 [0.73-0.88] and 0.85 [0.78-0.91], respectively, all p<0.001). Optimal cut-off values for HGI and peak RPP for discriminating all-cause mortality were 1.06 and 18,966, respectively.

CONCLUSION

Both HGI and peak RPP are predictors of mortality in patients with chronic HF and may be tools to signal need for advanced HF therapy evaluation.

Prognostic Value of Hemodynamic Gain Index in Patients With Heart Failure With Reduced Ejection Fraction

BACKGROUND

Assessment of functional capacity in patients with heart failure with reduced ejection fraction (HFrEF) is essential for risk stratification, and it traditionally relied on cardiopulmonary exercise testing (CPET)-derived peak oxygen consumption (peak Vo2).

OBJECTIVES

This study sought to investigate the prognostic value of alternative nonmetabolic exercise testing parameters in a contemporary cohort with HFrEF.

METHODS

Medical records of 1,067 consecutive patients with chronic HFrEF who underwent CPET from December 2012 to September 2020 were reviewed for a primary outcome that was a composite of all-cause mortality, left ventricular assist device implantation, and/or heart transplantation. Multivariable Cox regression and log-rank testing were used to determine prognostic values of various exercise testing variables.

RESULTS

The primary outcome was identified in 331 of 954 patients (34.7%) of the HFrEF cohort (median follow-up time, 946 days). After adjustment for demographics, cardiac parameters, and comorbidities, higher hemodynamic gain index (HGI) and peak rate-pressure product (RPP) were associated with greater event-free survival (adjusted HR per doubling: 0.76 and 0.36; 95% CI: 0.67-0.87 and 0.28-0.47; all P < 0.001, respectively). Moreover, HGI (area under the curve [AUC]: 0.69; 95% CI: 0.65-0.72) and peak RPP (AUC: 0.71; 95% CI: 0.68-0.74) were comparable to the standard peak Vo2 (AUC: 0.70; 95% CI: 0.66-0.73; P for comparison = 0.607 and 0.393, respectively) for primary outcome discrimination.

CONCLUSIONS

HGI and peak RPP show good correlation with peak Vo2 in terms of prognostication and outcome discrimination in patients with HFrEF and may serve as suitable alternatives to CPET-derived prognostic variables.

Time-Efficient, High-Resistance Inspiratory Muscle Strength Training Increases Exercise Tolerance in Midlife and Older Adults

PURPOSE

This study aimed to determine if time-efficient, high-resistance inspiratory muscle strength training (IMST), comprising 30 inhalation-resisted breaths per day, improves cardiorespiratory fitness, exercise tolerance, physical function, and/or regional body composition in healthy midlife and older adults.

METHODS

We performed a double-blind, randomized, sham-controlled clinical trial (NCT03266510) testing 6 wk of IMST (30 breaths per day, 6 d·wk -1 , 55%-75% maximal inspiratory pressure) versus low-resistance sham training (15% maximal inspiratory pressure) in healthy men and women 50-79 yr old. Subjects performed a graded treadmill exercise test to exhaustion, physical performance battery (e.g., handgrip strength, leg press), and body composition testing (dual x-ray absorptiometry) at baseline and after 6 wk of training.

RESULTS

Thirty-five participants (17 women, 18 men) completed high-resistance IMST ( n = 17) or sham training ( n = 18). Cardiorespiratory fitness (V̇O 2peak ) was unchanged, but exercise tolerance, measured as treadmill exercise time during a graded exercise treadmill test, increased with IMST (baseline, 539 ± 42 s; end intervention, 606 ± 42 s; P = 0.01) but not sham training (baseline, 562 ± 39 s; end intervention, 553 ± 38 s; P = 0.69). IMST increased peak RER (baseline, 1.09 ± 0.02; end intervention, 1.13 ± 0.02; P = 0.012), peak ventilatory efficiency (baseline, 25.2 ± 0.8; end intervention, 24.6 ± 0.8; P = 0.036), and improved submaximal exercise economy (baseline, 23.5 ± 1.1 mL·kg -1 ⋅min -1 ; end intervention, 22.1 ± 1.1 mL·kg -1 ⋅min -1 ; P < 0.001); none of these factors were altered by sham training (all P > 0.05). Changes in plasma acylcarnitines (targeted metabolomics analysis) were consistently positively correlated with changes in exercise tolerance after IMST but not sham training. IMST was associated with regional increases in thorax lean mass (+4.4%, P = 0.06) and reductions in trunk fat mass (-4.8%, P = 0.04); however, peripheral muscle strength, muscle power, dexterity, and mobility were unchanged.

CONCLUSIONS

These data suggest that high-resistance IMST is an effective, time-efficient lifestyle intervention for improving exercise tolerance in healthy midlife and older adults.

Role of confirmed and potential predictors of an unfavorable outcome in heart failure in everyday clinical practice

Heart failure (HF) is the only cardiovascular disease with an ever increasing incidence. HF, through reduced functional capacity, frequent exacerbations of disease, and repeated hospitalizations, results in poorer quality of life, decreased work productivity, and significantly increased costs of the public health system. The main challenge in the treatment of HF is the availability of reliable prognostic models that would allow patients and doctors to develop realistic expectations about the prognosis and to choose the appropriate therapy and monitoring method. At this moment, there is a lack of universal parameters or scales on the basis of which we could easily capture the moment of deterioration of HF patients' condition. Hence, it is crucial to identify such factors which at the same time will be widely available, cheap, and easy to use. We can find many studies showing different predictors of unfavorable outcome in HF patients: thorough assessment with echocardiography imaging, exercise testing (e.g., 6-min walk test, cardiopulmonary exercise testing), and biomarkers (e.g., N-terminal pro-brain type natriuretic peptide, high-sensitivity troponin T, galectin-3, high-sensitivity C-reactive protein). Some of them are very promising, but more research is needed to create a specific panel on the basis of which we will be able to assess HF patients. At this moment despite identification of many markers of adverse outcomes, clinical decision-making in HF is still predominantly based on a few basic parameters, such as the presence of HF symptoms (NYHA class), left ventricular ejection fraction, and QRS complex duration and morphology.

A novel machine-learning algorithm for predicting mortality risk after hip fracture surgery

INTRODUCTION

Although several risk stratification models have been developed to predict hip fracture mortality, efforts are still being placed in this area. Our aim is to (1) construct a risk prediction model for long-term mortality after hip fracture utilizing the RSF method and (2) to evaluate the changing effects over time of individual pre- and post-treatment variables on predicting mortality.

METHODS

1330 hip fracture surgical patients were included. Forty-five admission and in-hospital variables were analyzed as potential predictors of all-cause mortality. A random survival forest (RSF) algorithm was applied in predictors identification. Cox regression models were then constructed. Sensitivity analyses and internal validation were performed to assess the performance of each model. C statistics were calculated and model calibrations were further assessed.

RESULTS

Our machine-learning RSF algorithm achieved a c statistic of 0.83 for 30-day prediction and 0.75 for 1-year mortality. Additionally, a COX model was also constructed by using the variables selected by RSF, c statistics were shown as 0.75 and 0.72 when applying in 2-year and 4-year mortality prediction. The presence of post-operative complications remained as the strongest risk factor for both short- and long-term mortality. Variables including fracture location, high serum creatinine, age, hypertension, anemia, ASA, hypoproteinemia, abnormal BUN, and RDW became more important as the length of follow-up increased.

CONCLUSION

The RSF machine-learning algorithm represents a novel approach to identify important risk factors and a risk stratification models for patients undergoing hip fracture surgery is built through this approach to identify those at high risk of long-term mortality.

Clinical importance of respiratory muscle fatigue in patients with cardiovascular disease

Patients with cardiovascular diseases frequently experience exertional dyspnea. However, the relationship between respiratory muscle strength including its fatigue and cardiovascular dysfunctions remains to be clarified.The maximal inspiratory pressure/maximal expiratory pressure (MIP/MEP) before and after cardiopulmonary exercise testing (CPX) in 44 patients with heart failure and ischemic heart disease were measured. Respiratory muscle fatigue was evaluated by calculating MIP (MIPpost/MIPpre) and MEP (MEPpost/MEPpre) changes.The mean MIPpre and MEPpre values were 67.5 ± 29.0 and 61.6 ± 23.8 cm H2O, respectively. After CPX, MIP decreased in 25 patients, and MEP decreased in 22 patients. We evaluated the correlation relationship between respiratory muscle function including respiratory muscle fatigue and exercise capacity evaluated by CPX such as peak VO2 and VE/VCO2 slope. Among MIP, MEP, change in MIP, and change in MEP, only the value of change in MIP had an association with the value of VE/VCO2 slope (R = -0.36, P = .017). In addition, multivariate analysis for determining factor of change in MIP revealed that the association between the change in MIP and eGFR was independent from other confounding parameters (beta, 0.40, P = .017). The patients were divided into 2 groups, with (MIP change < 0.9) and without respiratory muscle fatigue (MIP change > 0.9), and a significant difference in peak VO2 (14.2 ± 3.4 [with fatigue] vs 17.4 ± 4.7 [without fatigue] mL/kg/min; P = .020) was observed between the groups.Respiratory muscle fatigue demonstrated by the change of MIP before and after CPX significantly correlated with exercise capacity and renal function in patients with cardiovascular disease.

Personalized Rate-Response Programming Improves Exercise Tolerance After 6 Months in People With Cardiac Implantable Electronic Devices and Heart Failure

Background:

Heart failure with reduced ejection fraction (HFrEF) is characterized by blunting of the positive relationship between heart rate and left ventricular (LV) contractility known as the force-frequency relationship (FFR). We have previously described that tailoring the rate-response programming of cardiac implantable electronic devices in patients with HFrEF on the basis of individual noninvasive FFR data acutely improves exercise capacity. We aimed to examine whether using FFR data to tailor heart rate response in patients with HFrEF with cardiac implantable electronic devices favorably influences exercise capacity and LV function 6 months later.

Methods:

We conducted a single-center, double-blind, randomized, parallel-group trial in patients with stable symptomatic HFrEF taking optimal guideline-directed medical therapy and with a cardiac implantable electronic device (cardiac resynchronization therapy or implantable cardioverter-defibrillator). Participants were randomized on a 1:1 basis between tailored rate-response programming on the basis of individual FFR data and conventional age-guided rate-response programming. The primary outcome measure was change in walk time on a treadmill walk test. Secondary outcomes included changes in LV systolic function, peak oxygen consumption, and quality of life.

Results:

We randomized 83 patients with a mean±SD age 74.6±8.7 years and LV ejection fraction 35.2±10.5. Mean change in exercise time at 6 months was 75.4 (95% CI, 23.4 to 127.5) seconds for FFR-guided rate-adaptive pacing and 3.1 (95% CI, −44.1 to 50.3) seconds for conventional settings (analysis of covariance; P =0.044 between groups) despite lower peak mean±SD heart rates (98.6±19.4 versus 112.0±20.3 beats per minute). FFR-guided heart rate settings had no adverse effect on LV structure or function, whereas conventional settings were associated with a reduction in LV ejection fraction.

Conclusions:

In this phase II study, FFR-guided rate-response programming determined using a reproducible, noninvasive method appears to improve exercise time and limit changes to LV function in people with HFrEF and cardiac implantable electronic devices. Work is ongoing to confirm our findings in a multicenter setting and on longer-term clinical outcomes.

Registration:

URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02964650.

Exercise Intolerance in Patients With Heart Failure: JACC State-of-the-Art Review

Exercise intolerance is the cardinal symptom of heart failure (HF) and is of crucial relevance, because it is associated with a poor quality of life and increased mortality. While impaired cardiac reserve is considered to be central in HF, reduced exercise and functional capacity are the result of key patient characteristics and multisystem dysfunction, including aging, impaired pulmonary reserve, as well as peripheral and respiratory skeletal muscle dysfunction. We herein review the different modalities to quantify exercise intolerance, the pathophysiology of HF, and comorbid conditions as they lead to reductions in exercise and functional capacity, highlighting the fact that distinct causes may coexist and variably contribute to exercise intolerance in patients with HF.

The Influence of Sex on Cardiac Physiology and Cardiovascular Diseases

Cardiovascular disease (CVD) is the leading cause of death world-wide. Most of treatment strategies were based on studies conducted on male patients. Studies have shown that significant differences exist between the two sexes in the development of CVD. There are certain differences between men and women in the structure and physiological functions of the heart such as left ventricular mass index, resting heart rate, and contractile function. Accordingly, the pathological features of the heart such as the extend of hypertrophy, fibrosis, and remodeling are also different. In addition, different genders also affect clinical symptoms, responses to treatment and prognosis in the development of CVD. Therefore, it is important to take these differences into consideration when design treatment options for men and women.

Differential prognostic impact between completion and non-completion of a 5-month cardiac rehabilitation program in outpatients with cardiovascular diseases

BACKGROUND

Cardiac rehabilitation (CR) is an essential component of care for patients with cardiovascular diseases (CVD). We aimed to evaluate clinical outcomes in outpatients with CVD who did and did not complete a 5-month CR program.

METHODS

Three hundred thirty-two outpatients with CVD who participated in a 5-month CR program and were followed-up for maximum 5 years were registered. We divided the patients into two groups: those who completed the CR program (success group, n = 175) and those who could not (non-success group, n = 157). Both long-term (5 years) and short-term (5 months) clinical outcomes were compared between the two groups.

RESULTS

There were no significant differences in patient characteristics at baseline between the success and non-success groups. With regard to both long-term and short-term clinical outcomes, the rates of all-cause death and hospital admission in the success group were significantly lower than those in the non-success group by a Kaplan-Meier analysis. There was a significant difference in short-term CVD death and hospital admission between the groups, but not for long-term CVD death and hospital. In long-term period, all-cause death and hospital admission was independently associated with completion of the CR program in addition to the presence of peripheral artery disease and VE vs. VCO₂ slope after adjusting for age, gender, body mass index, types of CVD and medications.

CONCLUSIONS

Completion of a 5-month CR program was associated with the prevention of all-cause death and hospital admission, but not CVD death and hospital admission in the long-term, which suggests that we need to reconsider this issue.

Are There Limitations to Exercise Benefits in Peripheral Arterial Disease?

Substantial evidence exists indicating that inactivity contributes to the progression of chronic disease, and conversely, that regular physical activity can both prevent the onset of disease as well as delay the progression of existing disease. To that end "exercise as medicine" has been advocated in the broad context as general medical care, but also in the specific context as a therapeutic, to be considered in much the same way as other drugs. As there are non-responders to many medications, there also are non-responders to exercise; individual who participate but do not demonstrate appreciable improvement/benefit. In some settings, the stress induced by exercise may aggravate an underlying condition, rather than attenuate chronic disease. As personalized medicine evolves with ready access to genetic information, so too will the incorporation of exercise in the context of those individual genetics. The focus of this brief review is to distinguish between the inherent capacity to perform, as compared to adaptive response to active exercise training in relation to cardiovascular health and peripheral arterial disease.

IL-1 Blockade in Patients With Heart Failure With Preserved Ejection Fraction

Background Enhanced inflammation may lead to exercise intolerance in heart failure with preserved ejection fraction. The aim of the current study was to determine whether IL (interleukin)-1 blockade with anakinra improved cardiorespiratory fitness in heart failure with preserved ejection fraction. Methods and Results Thirty-one patients with heart failure with preserved ejection fraction and CRP (C-reactive protein) >2 mg/L were randomized to anakinra (100 mg subcutaneously daily, N=21) or placebo (N=10) for 12 weeks. We measured peak oxygen consumption (Vo2), ventilatory efficiency (VE/Vco2 slope), and high-sensitivity CRP and NT-proBNP (N-terminal pro-B-type natriuretic peptide) at 4, 12, and 24 weeks. Twenty-eight patients completed ≥2 visits, 18 women (64%), 27 (96%) obese. There were no differences in peak Vo2 or VE/Vco2 slope between groups at baseline. Peak Vo2 was not changed after 12 weeks of anakinra (from 13.6 [11.8-18.0] to 14.2 [11.2-18.5] mL·kg-1·min-1, P=0.89), or placebo (14.9 [11.7-17.2] to 15.0 [13.8-16.9] mL·kg-1·min-1, P=0.40), without significant between-group differences in changes at 12 weeks (-0.4 [95% CI, -2.2 to +1.4], P=0.64). VE/Vco2 slope was also unchanged with anakinra (from 28.3 [27.2-33.0] to 30.5 [26.3-32.8], P=0.97) or placebo (from 31.6 [27.3-36.9] to 31.2 [27.8-33.4], P=0.78), without significant between-group differences in changes at 12 weeks (+1.2 [95% CI, -1.8 to +4.3], P=0.97). Within the anakinra-treated patients, high-sensitivity CRP and NT-proBNP levels were lower at 4 weeks compared with baseline ( P=0.026 and P=0.022 versus placebo [between-group analysis], respectively). Conclusions Treatment with anakinra for 12 weeks failed to improve peak Vo2 and VE/Vco2 slope in a group of obese heart failure with preserved ejection fraction patients. The favorable trends in high-sensitivity CRP and NT-proBNP with anakinra deserve exploration in future studies. Clinical Trial Registration URL: https://www.clinicaltrials.gov . Unique identifier: NCT02173548.

Cardiorespiratory Fitness and Reclassification of Risk for Incidence of Heart Failure

Background—

It is well established that cardiorespiratory fitness (CRF) is inversely associated with cardiovascular and all-cause mortality. However, little is known regarding the association between CRF and incidence of heart failure (HF).

Methods and Results—

Between 1987 and 2014, we assessed CRF in 21 080 HF-free subjects (58.3±11 years) at the Veterans Affairs Medical Centers in Washington, DC, and Palo Alto, CA. Subjects were classified by age-specific quintiles of CRF. Multivariable Cox models were used to determine the association between HF incidence and clinical and exercise test variables. Reclassification characteristics of fitness relative to standard clinical risk factors were determined using the category-free net reclassification improvement and integrated discrimination improvement indices. During the follow-up (mean 12.3±7.4 years), 1902 subjects developed HF (9.0%; average annual incidence rate, 7.4 events per 1000 person-years). When CRF was considered as a binary variable (unfit/fit), low fitness was the strongest predictor of risk for HF among clinical and exercise test variables (hazard ratio, 1.91; 95% confidence interval, 1.74–2.09; P <0.001). In a fully adjusted model with the least-fit group as the reference, there was a graded and progressive reduction in risk for HF as fitness level was higher. Risks for developing HF were 36%, 41%, 67%, and 76% lower among increasing quintiles of fitness compared with the least-fit subjects ( P <0.001). Adding CRF to standard risk factors resulted in a net reclassification improvement of 0.37 ( P <0.001).

Conclusions—

CRF is strongly, inversely, and independently associated with the incidence of HF in veterans referred for exercise testing.

Importance of Assessing Cardiorespiratory Fitness in Clinical Practice: A Case for Fitness as a Clinical Vital Sign: A Scientific Statement From the American Heart Association

Mounting evidence has firmly established that low levels of cardiorespiratory fitness (CRF) are associated with a high risk of cardiovascular disease, all-cause mortality, and mortality rates attributable to various cancers. A growing body of epidemiological and clinical evidence demonstrates not only that CRF is a potentially stronger predictor of mortality than established risk factors such as smoking, hypertension, high cholesterol, and type 2 diabetes mellitus, but that the addition of CRF to traditional risk factors significantly improves the reclassification of risk for adverse outcomes. The purpose of this statement is to review current knowledge related to the association between CRF and health outcomes, increase awareness of the added value of CRF to improve risk prediction, and suggest future directions in research. Although the statement is not intended to be a comprehensive review, critical references that address important advances in the field are highlighted. The underlying premise of this statement is that the addition of CRF for risk classification presents health professionals with unique opportunities to improve patient management and to encourage lifestyle-based strategies designed to reduce cardiovascular risk. These opportunities must be realized to optimize the prevention and treatment of cardiovascular disease and hence meet the American Heart Association's 2020 goals.

Características basales y cambios en el tratamiento tras el periodo de optimización de los pacientes incluidos en el estudio EFICAR

Objetivo

Se describen los datos basales de clase y capacidad funcional, comorbilidades, calidad de vida y cambios en la medicación durante la optimización del tratamiento, en pacientes con insuficiencia cardiaca y función sistólica deprimida (ICFSD) incluidos en el estudio EFICAR.

Diseño

Ensayo clínico aleatorizado multicéntrico.

Emplazamiento

Siete Centros de Salud.

Participantes

Ciento cincuenta pacientes con ICFSD; edad 68 ± 10 años, 77% varones

Mediciones

Variables sociodemográficas e índice de Charlson. Se evaluó la calidad de vida y la capacidad funcional Se realizó optimización del tratamiento.

Resultados

La etiología principal fue la cardiopatía isquémica (45%). Índice de Charlson global: 2,03 ± 1,05. El 31% ingresaron durante el último año por insuficiencia cardiaca. Fracción de eyección media: 37% ± 8. Clase funcional ii: 89%. Capacidad funcional con prueba de esfuerzo: 6,3 ± 1,6. Test 6 min: 446 ± 78 m. Test de la silla: 13,7 ± 4,4 s. Dinamómetro: 34,53 ± 10,12 kgf y 0,58 ± 0,16 bar. Short Form-36 Health Survey: salud física: 43,3 ± 8,4; salud mental: 50,1 ± 10,6. Minnesota Living with Heart Failure Questionnaire global: 22,8 ± 18,7. Tras optimizar el tratamiento no varió el porcentaje de pacientes ni la dosis media de fármacos analizados.

Conclusiones

La mayoría de los sujetos están en clase funcional ii, con capacidad funcional y calidad de vida disminuida e índice de comorbilidad elevado. Un ajuste protocolizado del tratamiento no consigue aumentar la dosis ni el número de pacientes con fármacos eficaces para la insuficiencia cardiaca con función cardiaca deprimida.

The association between the neutrophil/lymphocyte ratio and functional capacity in patients with idiopathic dilated cardiomyopathy

Objective:

The neutrophil/lymphocyte ratio (NLR) is an inexpensive, readily available and reliable inflammatory marker, which has a predictor value in different cardiovascular disorders. Functional capacity is one of the most important prognostic factors in patients with heart failure, which is usually stated as metabolic equivalents (MET). The goal of the study was to investigate the relationship between the NLR and functional capacity (FC) in patients with idiopathic dilated cardiomyopathy (IDC).

Methods:

Treadmill test according to modified-Bruce protocol was performed in 37 patients with IDC (mean age 46.7±11.7 years, 81.1% male) to assess their functional capacity. Baseline clinical and echocardiographic variables were obtained. Hematological and biochemical parameters were measured using standard techniques.

Results:

The patients were divided into low (<5 MET, n=18) and high (>5 MET, n=19) FC groups according to their functional status in the exercise test. The 2 groups were similar regarding age, gender and the presence of hypertension and diabetes mellitus. There was no significant difference between groups regarding echocardiographic parameters such as left ventricular ejection fraction and diameters. However, the NLR was significantly higher in low FC group compared to high FC group (3.62±2.24 vs. 2.24±0.67, p=0.002; respectively). There were significant negative correlations between the NLR, MET and left ventricular ejection fraction (r=-0.405, p=0.013 and r=-0.028, p=0.028; respectively). Diastolic dysfunction was present in all the patients with low functional capacity. A cut-off point of 2.26 for the NLR had 83% sensitivity and 69% specificity in predicting poor FC. After multivariate analysis, only the NLR remained significant predictor of poor functional status.

Conclusion:

We detected a significant association between the NLR and low FC, both of which has predictive and prognostic value in patients with heart failure. Functional capacity may depend on diastolic function rather than left ventricular ejection fraction in patients with IDC.

High inborn aerobic capacity does not protect the heart following myocardial infarction

Maximal oxygen uptake (Vo2max) is a strong prognostic marker for morbidity and mortality, but the cardio-protective effect of high inborn Vo2max remains unresolved. We aimed to investigate whether rats with high inborn Vo2max yield cardio-protection after myocardial infarction (MI) compared with rats with low inborn Vo2max. Rats breed for high capacity of running (HCR) or low capacity of running (LCR) were randomized into HCR-SH (sham), HCR-MI, LCR-SH, and LCR-MI. Vo2max was lower in HCR-MI and LCR-MI compared with respective sham (P < 0.01), supported by a loss in global cardiac function, assessed by echocardiography. Fura 2-AM loaded cardiomyocyte experiments revealed that HCR-MI and LCR-MI decreased cardiomyocyte shortening (39%, and 34% reduction, respectively, both P < 0.01), lowered Ca(2+) transient amplitude (37%, P < 0.01, and 20% reduction, respectively), and reduced sarcoplasmic reticulum (SR) Ca(2+) content (both; 20%, P < 0.01) compared with respective sham. Diastolic Ca(2+) cycling was impaired in HCR-MI and LCR-MI evidenced by prolonged time to 50% Ca(2+) decay that was partly explained by the 47% (P < 0.01) and 44% (P < 0.05) decrease in SR Ca(2+)-ATPase Ca(2+) removal, respectively. SR Ca(2+) leak increased by 177% in HCR-MI (P < 0.01) and 67% in LCR-MI (P < 0.01), which was abolished by inhibition of Ca(2+)/calmodulin-dependent protein kinase II. This study demonstrates that the effect of MI in HCR rats was similar or even more pronounced on cardiac- and cardiomyocyte contractile function, as well as on Ca(2+) handling properties compared with observations in LCR. Thus our data do not support a cardio-protective effect of higher inborn aerobic capacity.

Usefulness of preoperative exercise tolerance to predict late survival and symptom persistence after surgery for chronic nonischemic mitral regurgitation

Exercise duration during exercise treadmill testing (ETT) predicts long-term outcome among asymptomatic patients with mitral regurgitation. However, the prognostic value of preoperative exercise duration in patients who undergo mitral valve surgery is unknown. We examined findings among 45 prospectively followed (average 9.2 ± 4.3 years) patients (aged 54.8 ± 12.0 years, 45% men) with chronic isolated severe MR who underwent ETT before mitral valve surgery to test the hypotheses that exercise duration predicts long-term postoperative survival and persistent symptoms within 2 years after operation. During follow-up, 11 patients died; of these, 8 had persistent symptoms. Among patients who exercised >7 minutes, average annual postoperative all-cause and cardiovascular mortality risks were 0.75% (both endpoints) versus 5.4% and 4.8%, respectively, versus those who exercised ≤7 minutes (p = 0.003 all-cause, p = 0.007 cardiovascular). Exercise duration predicted postoperative deaths (p <.02 all cause, p <.04 cardiovascular) even when analysis was adjusted for preoperative variations in age, gender, medications, history of atrial fibrillation, and peak exercise heart rates. Other ETT, echocardiographic, and clinical variables were not independently associated with these outcomes when exercise duration was considered in the analysis. Preoperative exercise duration also predicted postoperative (New York Heart Association functional class ≥II) symptom persistence (p = 0.012), whereas other ETT, echocardiographic and clinical variables did not (NS, all). In conclusion, among patients who undergo surgery for chronic nonischemic mitral regurgitation, preoperative exercise duration, unlike many commonly used descriptors, is useful for predicting postoperative mortality and symptom persistence. Future research should determine whether interventions to improve exercise tolerance before mitral valve surgery can modify these postoperative outcomes.

Factors related to morbidity and mortality in patients with chronic heart failure with systolic dysfunction: the HF-ACTION predictive risk score model

BACKGROUND

We aimed to develop a multivariable statistical model for risk stratification in patients with chronic heart failure with systolic dysfunction, using patient data that are routinely collected and easily obtained at the time of initial presentation.

METHODS AND RESULTS

In a cohort of 2331 patients enrolled in the HF-ACTION (Heart Failure: A Controlled Trial Investigating Outcomes of Exercise TraiNing) study (New York Heart Association class II-IV, left ventricular ejection fraction ≤0.35, randomized to exercise training and usual care versus usual care alone, median follow-up of 2.5 years), we performed risk modeling using Cox proportional hazards models and analyzed the relationship between baseline clinical factors and the primary composite end point of death or all-cause hospitalization and the secondary end point of all-cause death alone. Prognostic relationships for continuous variables were examined using restricted cubic spline functions, and key predictors were identified using a backward variable selection process and bootstrapping methods. For ease of use in clinical practice, point-based risk scores were developed from the risk models. Exercise duration on the baseline cardiopulmonary exercise test was the most important predictor of both the primary end point and all-cause death. Additional important predictors for the primary end point risk model (in descending strength) were Kansas City Cardiomyopathy Questionnaire symptom stability score, higher serum urea nitrogen, and male sex (all P<0.0001). Important additional predictors for the mortality risk model were higher serum urea nitrogen, male sex, and lower body mass index (all P<0.0001).

CONCLUSIONS

Risk models using simple, readily obtainable clinical characteristics can provide important prognostic information in ambulatory patients with chronic heart failure with systolic dysfunction.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00047437.

Impact of exercise on heart rate recovery

BACKGROUND

Abnormal heart rate recovery (HRR) has been shown to predict mortality. Although small studies have found that HRR can be improved with cardiac rehabilitation, it is unknown whether an improvement would affect mortality. The aim of this study was to determine whether HRR could be improved with cardiac rehabilitation and whether it would be predictive of mortality.

METHODS AND RESULTS

We evaluated 1070 consecutive patients who underwent exercise stress testing before and after completion of a phase 2 cardiac rehabilitation program. Heart rate recovery, defined as the difference between heart rate at peak exercise and exactly 1 minute into the recovery period, and mortality were followed up as the primary end points. Of 544 patients with abnormal baseline HRR, 225 (41%) had normal HRR after rehabilitation. Of the entire cohort, 197 patients (18%) died. Among patients with an abnormal HRR at baseline, failure to normalize after rehabilitation predicted a higher mortality (P<0.001). After multivariable adjustment, the presence of an abnormal HRR at exit was predictive of death in all patients (hazard ratio, 2.15; 95% confidence interval 1.43-3.25). Patients with abnormal HRR at baseline who normalized afterward had survival rates similar to those of the group with normal HRR at baseline and after cardiac rehabilitation (P=0.143).

CONCLUSIONS

Heart rate recovery improved after phase 2 cardiac rehabilitation in the overall cohort. There was a strong association of abnormal HRR at exit with all-cause mortality. Patients with abnormal HRR at baseline who normalized HRR with exercise had a mortality similar to that of individuals with baseline normal HRR.

Cardiorespiratory fitness is positively correlated with cerebral white matter integrity in healthy seniors

High cardiorespiratory fitness (CRF) is an important protective factor reducing the risk of cardiac-related disability and mortality. Recent research suggests that high CRF also has protective effects on the brain's macrostructure and functional response. However, little is known about the potential relationship between CRF and the brain's white matter (WM) microstructure. This study explored the relationship between a comprehensive measure of CRF (VO(2) peak, total time on treadmill, and 1-minute heart rate recovery) and multiple diffusion tensor imaging measures of WM integrity. Participants were 26 healthy community dwelling seniors between the ages of 60 and 69 (mean=64.79 years, SD=2.8). Results indicated a positive correlation between comprehensive CRF and fractional anisotropy (FA) in a large portion of the corpus callosum. Both VO(2) peak and total time on treadmill contributed significantly to explaining the variance in mean FA in this region. The CRF-FA relationship observed in the corpus callosum was primarily characterized by a negative correlation between CRF and radial diffusivity in the absence of CRF correlations with either axial diffusivity or mean diffusivity. Tractography results demonstrated that portions of the corpus callosum associated with CRF primarily involved those interconnecting frontal regions associated with high-level motor planning. These results suggest that high CRF may attenuate age-related myelin declines in portions of the corpus callosum that interconnect homologous premotor cortex regions involved in motor planning.

Combined effect of cardiorespiratory fitness and adiposity on mortality in patients with coronary artery disease

BACKGROUND

High cardiorespiratory fitness and body mass index (BMI) are associated with decreased mortality in patients with coronary artery disease. Our objective was to determine the joint impact of fitness and adiposity measures on all-cause mortality in this subgroup.

METHODS

Coronary artery disease patients (n = 855) enrolled in the Mayo Clinic cardiac rehabilitation program from 1993 to 2007 were included. Fitness levels were determined by cardiopulmonary exercise testing. Patients were divided into low and high fitness by sex-specific median values of peak oxygen consumption and total treadmill time. Adiposity was measured through BMI and waist-to-hip ratio (WHR).

RESULTS

There were 159 deaths during 9.7 ± 3.6 years of mean follow-up. After adjusting for potential confounding factors, low fitness, shorter treadmill time, low BMI, and high WHR were significantly associated with increased mortality. Using low WHR-high fitness group as reference, significantly increased mortality was noted in low WHR-low fitness (hazard ratio 4.2, 95% CI, 1.8-9.8), centrally obese-high fitness (2.3, 1.0-5.4), and centrally obese-low fitness (6.1, 2.7-13.6) groups. Overweight-high fitness (2.2, 0.63-7.4), obese-high fitness (3.2, 0.88-11.4), and obese-low fitness (3.3, 0.96-11.4) subjects did not have a significantly different mortality as compared with the reference group of normal weight-high fitness subjects, whereas normal weight-low fitness (9.6, 2.9-31.8) and overweight-low fitness (6.8, 2.1-22.2) groups had significantly increased mortality.

CONCLUSIONS

Low fitness and central obesity were independently and cumulatively associated with increased mortality in coronary artery disease patients attending cardiac rehabilitation. The association of BMI with mortality is complex and altered by fitness levels.

Use of reclassification for assessment of improved prediction: an empirical evaluation

BACKGROUND

An increasing number of studies evaluate the ability of predictors to change risk stratification and alter medical decisions, i.e. reclassification performance. We examined the reported design and analysis of recent studies of reclassification and the robustness of their claims for improved reclassification.

METHODS

Two independent investigators searched PubMed and citations to the article that introduced the currently most popular reclassification metric (net reclassification index, NRI) to identify studies performing reclassification analysis (January 2006-January 2010). We focused on articles that included any analyses comparing the performance of a baseline predictive model vs the baseline model plus some additional predictor for a prospectively assessed outcome. We recorded information on the baseline model used, outcomes assessed, choice of risk thresholds and features of reclassification analyses.

RESULTS

Of 58 baseline models used in 51 eligible papers, only 14 (24%) were previously described, used as described and had same outcomes as originally intended. Calibration was examined in 53% of the studies. Sixteen studies (31%) provided a reference for the choice of risk thresholds and only six used the previously proposed categories or justified the use of alternative thresholds. Only 14 studies (27%) stated that the chosen risk thresholds had different therapeutic intervention implications. NRI was calculated in 38 studies and was smaller in studies with adequately referenced or justified risk thresholds vs others (P < 0.0001).

CONCLUSIONS

Reclassification studies would benefit from more rigorous methodological standards; otherwise claims for improved reclassification may remain spurious.

Identifying important risk factors for survival in patient with systolic heart failure using random survival forests

BACKGROUND

Heart failure survival models typically are constructed using Cox proportional hazards regression. Regression modeling suffers from a number of limitations, including bias introduced by commonly used variable selection methods. We illustrate the value of an intuitive, robust approach to variable selection, random survival forests (RSF), in a large clinical cohort. RSF are a potentially powerful extensions of classification and regression trees, with lower variance and bias.

METHODS AND RESULTS

We studied 2231 adult patients with systolic heart failure who underwent cardiopulmonary stress testing. During a mean follow-up of 5 years, 742 patients died. Thirty-nine demographic, cardiac and noncardiac comorbidity, and stress testing variables were analyzed as potential predictors of all-cause mortality. An RSF of 2000 trees was constructed, with each tree constructed on a bootstrap sample from the original cohort. The most predictive variables were defined as those near the tree trunks (averaged over the forest). The RSF identified peak oxygen consumption, serum urea nitrogen, and treadmill exercise time as the 3 most important predictors of survival. The RSF predicted survival similarly to a conventional Cox proportional hazards model (out-of-bag C-index of 0.705 for RSF versus 0.698 for Cox proportional hazards model).

CONCLUSIONS

An RSF model in a cohort of patients with heart failure performed as well as a traditional Cox proportional hazard model and may serve as a more intuitive approach for clinicians to identify important risk factors for all-cause mortality.

Application of the Seattle Heart Failure Model in ambulatory patients presented to an advanced heart failure therapeutics committee

BACKGROUND

We sought to assess the predictive value of the Seattle Heart Failure Model (SHFM) when applied to ambulatory patients with advanced heart failure (HF) presented to an advanced HF therapeutics committee at a tertiary care US institution.

METHODS AND RESULTS

We evaluated model discrimination and calibration in 215 consecutive ambulatory patients who were presented to the Cleveland Clinic advanced HF therapeutics committee between 2004 to 2007 for evaluation for advanced options including transplantation and ventricular assist device (VAD). Analyses were stratified by committee decision (not listed versus listed United Network of Organ Sharing [UNOS] Status 2). Eighty-five percent had 1 or no missing SHFM variables. The primary outcome was a composite of all-cause mortality, VAD, or urgent (UNOS Status 1) transplantation. During a median follow-up of 24 months, 68 died, 18 received VAD support, and 81 underwent heart transplantation. Discrimination was modest both for those not listed (c-index, 0.683 at 1 year and 0.648 at 2 years), and for those listed UNOS status 2 (c-index, 0.629 at 1 year and 0.628 at 2 years). Calibration was acceptable among those patients not listed for heart transplantation but with substantial underestimation of risk (ie, overestimation of survival free of VAD or urgent transplantation) among UNOS status 2 patients.

CONCLUSIONS

In ambulatory patients presented to an advanced HF therapeutics committee for evaluation for heart transplantation, the SHFM offers modest discrimination of risk for the primary composite outcome of mortality, VAD, or urgent transplantation, with underestimation of risk in those patients listed for nonurgent transplantation. Interpretation of risk prediction by the SHFM in this patient population must be done with caution.

How much information can metabolic syndrome provide? An application of information theory

The purpose of this article is to show, using principles from Shannon's information theory, that it is possible to estimate the amount of information loss that occurs, in relative terms, when multiple continuous biological traits are dichotomized and aggregated, as is the case with many diagnostic definitions. We use metabolic syndrome as a case in point. It is our position that this type of information loss can impede the progress of medical research. This argument will first be made on theoretical grounds and then be supplemented using data from a clinical trial involving 252 women enrolled in cardiac rehabilitation. After laying out relevant principles, we conduct analyses to show how such information loss occurs during data transformation. Our analyses demonstrate that transforming the multiple traits that comprise metabolic syndrome into a single binary indicator discarded over 98% of the potential information contained in the original measurements. We go on to illustrate how such information loss impedes the establishment of meaningful statistical relationships with an indicator of cardiovascular health, time on an exercise tolerance test.

The myocardial contractile response to physiological stress improves with high saturated fat feeding in heart failure

Impaired myocardial contractile function is a hallmark of heart failure (HF), which may present under resting conditions and/or during physiological stress. Previous studies have reported that high fat feeding in mild to moderate HF/left ventricular (LV) dysfunction is associated with improved contractile function at baseline. The goal of this study was to determine whether myocardial function is compromised in response to physiological stress and to evaluate the global gene expression profile of rats fed high dietary fat after infarction. Male Wistar rats underwent ligation or sham surgery and were fed normal chow (NC; 10% kcal fat; Sham + NC and HF + NC groups) or high-fat chow (SAT; 60% kcal saturated fat; Sham + SAT and HF + SAT groups) for 8 wk. Myocardial contractile function was assessed using a Millar pressure-volume conductance catheter at baseline and during inferior vena caval occlusions and dobutamine stress. Steady-state indexes of systolic function, LV +dP/dt(max), stroke work, and maximal power were increased in the HF + SAT group versus the HF + NC group and reduced in the HF + NC group versus the Sham + NC group. Preload recruitable measures of contractility were decreased in HF + NC group but not in the HF + SAT group. beta-Adrenergic responsiveness [change in LV +dP/dt(max) and change in cardiac output with dobutamine (0-10 microg x kg(-1) x min(-1))] was reduced in HF, but high fat feeding did not further impact the contractile reserve in HF. The contractile reserve was reduced by the high-fat diet in the Sham + SAT group. Microarray gene expression analysis revealed that the majority of significantly altered pathways identified contained multiple gene targets correspond to cell signaling pathways and energy metabolism. These findings suggest that high saturated fat improves myocardial function at rest and during physiological stress in infarcted hearts but may negatively impact the contractile reserve under nonpathological conditions. Furthermore, high fat feeding-induced alterations in gene expression related to energy metabolism and specific signaling pathways revealed promising targets through which high saturated fat potentially mediates cardioprotection in mild to moderate HF/LV dysfunction.