Nomogram based on metabolic equivalents and age for assessing aerobic exercise capacity in men

Correlation between workload-indexed blood pressure response to exercise (SBP/MET slope) and clinical and echocardiographic parameters among normotensive Olympic athletes

INTRODUCTION

The workload-indexed systolic blood pressure response to exercise (SBP/MET slope) has been proposed as a novel parameter for evaluating abnormal blood pressure response to exercise (ABPR) and its potential risks. Aim of our study was to assess the association between SBP/MET slope and clinical and cardiac dimensional parameters in normotensive athletes.

METHODS

A cohort of 292 normotensive Olympic athletes (155 male, 53.1 %) underwent a pre-participation evaluation that included clinical, echocardiographic, and exercise-stress test parameters. The SBP/MET slope was calculated as the increase in systolic blood pressure indexed to metabolic equivalents achieved during maximal exercise. Athletes were stratified into quartiles based on their SBP/MET slope, and comparisons across quartiles were made.

RESULTS

Athletes in the highest SBP/MET slope quartile exhibited increased left ventricular wall thickness, i.e., interventricular septum (IVS) compared to those in lower quartiles (10.3 ± 0.9 vs. 9.5 ± 1.1, p = 0.014). Male athletes predominated in higher quartiles (p = 0.047), and endurance athletes were absent in the higher groups (p = 0.006). No differences were observed for systolic or diastolic function across quartiles. At multivariate analysis, SBP/MET slope was indipendently correlated to IVS (p = 0.040; R2 = 0.566, standardized beta coefficient = 0.368) and inversely correlated to W/Kg (p = 0.014; R2 = 0.566, standardized beta coefficient = -0.507). After a follow-up of 10.3 ± 2.6 years, 13.6 % of athletes in the highest quartile developed hypertension.

CONCLUSION

Athletes with higher SBP/MET slope exhibited increased wall thickness and lower exercise capacity and showed higher risk for late-onset hypertension. Long-term follow-up studies are warranted to further elucidate its prognostic implications.

Diastolic Stress Echocardiography in Patients With Hypertrophy Cardiomyopathy: Association With Exercise Capacity

Diastolic dysfunction plays a major role in precipitating congestive heart failure in patients with hypertrophic cardiomyopathy (HCM). In many such patients, symptoms are unmasked only during exercise because left ventricular (LV) filling pressure is normal at rest but increase with exercise. We sought to establish whether abnormal postexercise diastolic parameters are associated with reduced exercise capacity in patients with HCM. We examined 590 patients with asymptomatic/minimally symptomatic HCM (age 54 ± 14 years, 57% men, body mass index 30 ± 6 kg/m2, 84% on β blockers) with HCM by 2-dimensional and Doppler echocardiography at rest and after maximal treadmill exercise echocardiography (TSE). A complete echocardiogram (including LV ejection fraction, LV thickness, LV outflow tract [LVOT] gradient, degree of mitral regurgitation) was recorded. Diastolic parameters (septal and lateral [e'] velocities of the mitral annulus, peak early [E] and late [A] mitral inflow velocity, E/A ratio, E/e', right ventricular systolic pressure [RVSP], and left atrial volume index) were recorded at rest and after TSE. Exercise functional capacity was recorded and divided into <85% or >85% of age-gender predicted metabolic equivalents (AGP-METs). After maximal exercise, 32% patients had at least moderate mitral regurgitation, mean LVOT gradient was 61 ± 59 mm Hg, E/A ratio was 1.2 ± 1.0, average E/e' ratio 12.9 ± 1.0, and peak RVSP was 36 ± 15 mm Hg. Only 42% of patients achieved >85% of AGP-METs; the mean METs was 7 ± 3. On multivariable logistic regression analysis, higher body mass index (odds ratio [OR] 1.05), β-blocker use (OR 2.58), higher left atrial volume index (OR 1.02), higher peak stress LVOT gradient (LVOTG) (OR 1.06), peak stress E/e' (OR 1.04), and higher RVSP (OR 1.03) were independently associated with <85% AGP-METs achieved (all p <0.05). In conclusion, in patients with asymptomatic/minimally symptomatic HCM who underwent TSE, there is a significant and independent association between abnormal diastolic response to exercise and reduced exercise capacity in HCM. Incorporating diastolic parameters during stress echocardiography could provide incremental diagnostic utility in deciphering the exact etiology of dyspnea in such patients.

Comparative Analysis of Respiratory and Functional Outcomes in Children Post-Fontan Procedure Versus Healthy Peers

Studies have shown that respiratory muscle training enhances functional capacity and pulmonary function in Fontan patients. However, diaphragm muscle characteristics in Fontan children have not been fully elucidated. The aim of this study was to compare respiratory function, maximal and submaximal functional capacities, and quality of life, as well as to assess diaphragm mobility and thickness, between Fontan patients aged 8 to 12 years and healthy individuals. This cross-sectional study included 45 children-27 Fontan patients, Fontan Group (FG) and 18 healthy control Group (CG) subjects. Different examinations were performed: spirometry was used to analyze pulmonary volume and capacity; manovacuometry was used to determine respiratory muscle strength; chest ultrasound was used to determine diaphragm muscle characteristics; cardiopulmonary exercise and the six-minute walk test (6MWT) were used to determine functional capacity; the AUQEI questionnaire was used to determine quality of life. Descriptive analysis and intergroup comparisons were performed for all the data. Compared with the CG, the FG exhibited impaired pulmonary function and reduced functional capacity. Significant differences in median values were noted for forced expiratory volume in one second (FEV1): 2.39 L/min, p = 0.002; forced vital capacity (FVC): 1.73 vs. 3.06 L/min, p = 0.002; maximal inspiratory pressure: - 73 vs. - 117 cmH2O, p = 0.007; absolute peak VO2: 1.09 vs. 1.51 L/min, p < 0.001; relative peak VO2: 31.9 vs. 42.5 mL/kg/min, p = 0.003; and 6MWT distance: 420 vs. 586 m, p < 0.001. Diaphragmatic thickness, mobility and quality of life were similar between the groups. Despite the reduced functional capacity, impaired pulmonary volume and capacity, and respiratory muscle weakness of the FG compared to those of the CG, the diaphragm characteristics and quality of life were similar between the groups.

Guideline for the application of heart rate and heart rate variability in occupational medicine and occupational health science

This updated guideline replaces the "Guideline for the application of heart rate and heart rate variability in occupational medicine and occupational health science" first published in 2014. Based on the older version of the guideline, the authors have reviewed and evaluated the findings on the use of heart rate (HR) and heart rate variability (HRV) that have been published in the meantime and incorporated them into a new version of this guideline.This guideline was developed for application in clinical practice and research purposes in the fields of occupational medicine and occupational science to complement evaluation procedures with respect to exposure and risk assessment at the workplace by the use of objective physiological workload indicators. In addition, HRV is also suitable for assessing the state of health and for monitoring the progress of illnesses and preventive medical measures. It gives an overview of factors influencing the regulation of the HR and HRV at rest and during work. It further illustrates methods for measuring and analyzing these parameters under standardized laboratory and real workload conditions, areas of application as well as the quality control procedures to be followed during the recording and evaluation of HR and HRV.

Improving Reporting of Exercise Capacity Across Age Ranges Using Novel Workload Reference Equations

Exercise capacity (EC) is an important predictor of survival in the general population and in subjects with cardiopulmonary disease. Despite its relevance, considering the percent-predicted workload (%pWL) given by current equations may overestimate EC in older adults. Therefore, to improve the reporting of EC in clinical practice, our main objective was to develop workload reference equations (pWL) that better reflect the relation between workload and age. Using the Fitness Registry and the Importance of Exercise National Database (FRIEND), we analyzed a reference group of 6,966 apparently healthy participants and 1,060 participants with heart failure who underwent graded treadmill cardiopulmonary exercise testing. For the first group, the mean age was 44 years (18 to 79); 56.5% of participants were males and 15.4% had obesity. Peak oxygen consumption was 11.6 ± 3.0 METs in males and 8.5 ± 2.4 METs in females. After partition analysis, we first developed sex-specific pWL equations to allow comparisons to a healthy weight reference. For males, pWL (METs) = 14.1-0.9×10-3×age2 and 11.5-0.87×10-3×age2 for females. We used those equations as denominators of %pWL, and based on their distribution, we determined thresholds for EC classification, with average EC defined by the range corresponding to 85% to 115%pWL. Compared with %pWL using current equations, the new equations yielded better-calibrated %pWL across different age ranges. We also derived body mass index-adjusted pWL equations that better assessed EC in subjects with heart failure. In conclusion, the novel pWL equations have the potential to impact the report of EC in practice.

Clinical and Echocardiographic Diversity Associated With Physical Fitness in the Project Baseline Health Study: Implications for Heart Failure Staging

BACKGROUND

Clinical and echocardiographic features may carry diverse information about the development of heart failure (HF). Therefore, we determined heterogeneity in clinical and echocardiographic phenotypes and its association with exercise capacity.

METHODS

In 2036 community-dwelling individuals, we defined echocardiographic profiles of left and right heart remodeling and dysfunction. We subdivided the cohort based on presence (+) or absence (-) of HF risk factors (RFs) and echocardiographic abnormalities (RF-/Echo-, RF-/Echo+, RF+/Echo-, RF+/Echo+). Multivariable-adjusted associations between subgroups and physical performance metrics from 6-minute walk and treadmill exercise testing were assessed.

RESULTS

The prevalence was 35.3% for RF-/Echo-, 4.7% for RF-/Echo+, 39.3% for RF+/Echo-, and 20.6% for RF+/Echo+. We observed large diversity in echocardiographic profiles in the Echo+ group. Participants with RF-/Echo+ (18.6% of Echo+) had predominantly echocardiographic abnormalities other than left ventricular (LV) diastolic dysfunction, hypertrophy and reduced ejection fraction, whereas their physical performance was similar to RF-/Echo-. In contrast, participants with RF+/Echo+ presented primarily with LV hypertrophy or dysfunction, features that related to lower 6-minute walking distance and lower exercise capacity.

CONCLUSIONS

Subclinical echocardiographic abnormalities suggest HF pathogenesis, but the presence of HF risk factors and type of echo abnormality should be considered so as to distinguish adverse from benign adaptation and to stratify HF risk.

Clinical Outcomes of Percutaneous Fontan Stenting in Adults

BACKGROUND

Fontan pathway stenosis is a well-known complication after palliation. Percutaneous stenting is effective for angiographic/hemodynamic relief of Fontan obstruction, but its clinical impact in adults remains unknown.

METHODS

This was a retrospective cohort of 26 adults undergoing percutaneous stenting for Fontan obstruction from 2014 to 2022. Procedural details, functional capacity, and liver parameters were reviewed at baseline and during follow-up.

RESULTS

Median age was 22.5 years (interquartile range [IQR] 19-28.8 y); 69% were male. After stenting, Fontan gradient significantly decreased (2.0 ± 1.9 vs 0 [IQR 0-1] mm Hg; P < 0.005), and minimal Fontan diameter increased (11.3 ± 2.9 vs 19.3 [IQR 17-20] mm; P < 0.001). One patient developed acute kidney injury periprocedurally. During a follow-up of 2.1 years (IQR 0.6-3.7 y), 1 patient had thrombosis of the Fontan stent and 2 underwent elective Fontan re-stenting. New York Heart Association functional class improved in 50% of symptomatic patients. Changes in functional aerobic capacity on exercise testing were directly related to pre-stenting Fontan gradient (n = 7; r = 0.80; P = 0.03) and inversely related to pre-stenting minimal Fontan diameter (r = -0.79; P = 0.02). Thrombocytopenia (platelet count < 150 109/L) was present in 42.3% of patients before and in 32% after the procedure (P = 0.08); splenomegaly (spleen size > 13 cm) was present in 58.3% and 58.8% (P = 0.57), respectively. Liver fibrosis (aspartate transaminase to platelet ratio index and Fibrosis-4) scores were unchanged after the procedure compared with baseline.

CONCLUSIONS

Percutaneous stenting in adults is safe and effective in relieving Fontan obstruction, resulting in subjective improvement in functional capacity in some. A subset of patients demonstrated improvement in markers of portal hypertension, suggesting that Fontan stenting could improve Fontan-associated liver disease in select individuals.

Symptom-limited exercise capacity is associated with long-term survival

The prognostic value of exercise capacity has been demonstrated in subjects with established cardiovascular diseases. We aim to evaluate the independence of exercise capacity measured by treadmill exercise test (TET) in predicting long-term outcomes among various comorbidities. This study was conducted from January 2003 to December 2012 in a tertiary medical center in Taiwan. Subjects referred for symptom-limited TET were recruited. Peak achieved metabolic equivalents (METs) were determined by treadmill grade and speed at peak exercise. The main outcomes were cardiovascular and all-cause mortality by linking to the National Death Registry. A total of 18,954 participants (57.8 ± 12.8 years, 62% men) achieved a mean peak METs of 9.2. Subjects in the lowest tertile of peak METs were older, had poorer renal function, lower hemoglobin, and more comorbidities. During a median follow-up of 4.3 years, there were 642 mortalities and 132 cardiovascular deaths. Peak METs significantly predicted cardiovascular death and all-cause mortality in the multivariable Cox regression models [hazard ratio (95% confidence intervals): 0.788 (0.660-0.940) and 0.835 (0.772-0.903), respectively]. The prognostic influence of peak METs consistently appeared in the subgroups, regardless of age, gender, body weight, comorbidities, use of beta-blockers, or the presence of exercise-induced ischemia. The fitness was more predictive of long-term outcomes in young or those with ischemic changes during TET (P for interaction: 0.035 and 0.018, respectively). The benefit of fitness was nonlinearly associated with long-term survival. The prognostic impacts of exercise capacity were universally observed in subjects with or without various comorbidities.

The relationship between mitral regurgitant severity, symptoms, and exercise capacity in primary degenerative mitral regurgitation

Although it is assumed that more severe MR is associated with a greater burden of symptoms and lower exercise capacity, the relationship between symptoms, exercise capacity, and mitral regurgitant severity has not been well studied. We prospectively studied 67 (63 ± 11 years, 72% male) patients with at least mild degenerative MR and left ventricular ejection fraction ≥ 50% who underwent stress echocardiography, CMR, and evaluation with the Kansas City Cardiomyopathy questionnaire (KCCQ). Symptoms and exercise capacity were evaluated in the context of MR severity. Patients reporting dyspnea had lower KCCQ symptom scores (79 ± 23 vs. 96 ± 9, p = 0.01) and achieved lower percentage of age and gender predicted METs (114 ± 37 vs. 152 ± 43%, p < 0.001) compared to those without dyspnea. There was no significant difference in MR volume between those with vs. without dyspnea by CMR (43 ± 26 ml vs. 51 ± 28 ml, p = 0.3) or echocardiography (64 ± 28 vs. 73 ± 41ml, p = 0.4). Those with severe MR by CMR had similar KCCQ symptom scores (96 ± 10 vs. 89 ± 17, p = 0.04) and percentage of age and gender predicted METs (148 ± 42 vs. 133 ± 47%, p = 0.2) to those without severe MR. Those with severe MR by echocardiography had similar KCCQ symptom score (93 ± 15 vs. 89 ± 16, p = 0.3) and percentage of age and gender predicted METs (138 ± 43 vs. 153 ± 46%, p = 0.2) to those without severe MR. Patients with degenerative MR assessed by CMR and stress echocardiography, there was no relationship between MR severity and either symptoms or exercise capacity. These findings highlight the disconnect between symptoms and the severity of MR and challenge the assumption that correcting MR can be counted on to improve symptom status in patients with degenerative MR.

Sex Differences in Quality of Life in Patients with Ischemia with No Obstructive Coronary Artery Disease (INOCA): A Patient Self-Report Retrospective Survey from INOCA International

Women with obstructive coronary artery disease (CAD) have a relatively lower quality of life (QoL) compared to men, but our understanding of sex differences in QoL in ischemia with no obstructive coronary artery disease (INOCA) is limited. We conducted a survey of patient members of INOCA International with an assessment of self-reported health measures. Functional capacity was retrospectively estimated using the Duke Activity Status Index (DASI), assessing levels of activities performed before and after INOCA symptom onset. Of the 1579 patient members, the overall survey completion rate was 21%. Women represented 91% of the respondents. Estimated functional capacity, expressed as metabolic equivalents (METs), was higher before compared to after INOCA diagnosis comparably for both women and men. For every one MET decline in functional capacity, there was a significantly greater decline in QoL for men compared with women in physical health (4.0 ± 1.1 vs. 2.9 ± 0.3 days/month, p < 0.001), mental health (2.4 ± 1.2 vs. 1.8 ± 0.3 days/month, p = 0.001), and social health/recreational activities (4.1 ± 1.0 vs. 2.9 ± 0.3 days/month, p = 0.0001), respectively. In an international survey of patients living with INOCA, despite similar diagnoses, clinical comorbidities, and symptoms, INOCA-related functional capacity declines are associated with a greater adverse impact on QoL in men compared to women.

Korean vs. Western Exercise Capacity Nomograms for Korean Patients With Cardiovascular Disease

BACKGROUND

Exercise capacity is known to be an independent predictor of cardiovascular events and mortality. However, most previous studies were based on Western populations. Further study is warranted for Asian patients according to ethnic or national standards. We aimed to compare prognostic values of Korean and Western nomograms for exercise capacity in Korean patients with cardiovascular disease (CVD).

METHODS

In this retrospective cohort study, we enrolled 1,178 patients (62 ± 11 years; 78% male) between June 2015 and May 2020, who were referred for cardiopulmonary exercise testing in our cardiac rehabilitation program. The median follow-up period was 1.6 years. Exercise capacity was measured in metabolic equivalents by direct gas exchange method during the treadmill test. The nomogram for exercise capacity from healthy Korean individuals and a previous landmark Western study was used to determine the percentage of predicted exercise capacity. The primary endpoint was the composite of major adverse cardiovascular events (MACE; all-cause death, myocardial infarction, repeat revascularization, stroke and hospitalization for heart failure).

RESULTS

A multivariate analysis showed that the risk of primary endpoint was more than double (hazard ratio [HR], 2.20; 95% confidence interval [CI], 1.10-4.40) in the patients with lower exercise capacity (< 85% of predicted) by Korean nomogram. The lower exercise capacity was one of the strong independent predictors along with left ventricular ejection fraction, age, and level of hemoglobin. However, the lower exercise capacity by Western nomogram could not predict the primary endpoint (HR, 1.33; 95% CI, 0.85-2.10).

CONCLUSION

Korean patients with CVD with lower exercise capacity have higher risk of MACE. Considering inter-ethnic differences in cardiorespiratory fitness, the Korean nomogram provides more suitable reference values than the Western nomogram to determine lower exercise capacity and predict cardiovascular events in Korean patients with CVD.

Functional and Metabolic Imaging in Heart Failure with Preserved Ejection Fraction: Promises, Challenges, and Clinical Utility

Heart failure with preserved ejection fraction (HFpEF) is recognised as an increasingly prevalent, morbid and burdensome condition with a poor outlook. Recent advances in both the understanding of HFpEF and the technological ability to image cardiac function and metabolism in humans have simultaneously shone a light on the molecular basis of this complex condition of diastolic dysfunction, and the inflammatory and metabolic changes that are associated with it, typically in the context of a complex patient. This review both makes the case for an integrated assessment of the condition, and highlights that metabolic alteration may be a measurable outcome for novel targeted forms of medical therapy. It furthermore highlights how recent technological advancements and advanced medical imaging techniques have enabled the characterisation of the metabolism and function of HFpEF within patients, at rest and during exercise.

Percentage of Age-Predicted Cardiorespiratory Fitness May Be a Stronger Risk Indicator for Incident Type 2 Diabetes Than Absolute Levels of Cardiorespiratory Fitness

PURPOSE

There are inverse and independent associations between cardiorespiratory fitness (CRF) and several adverse cardiometabolic outcomes. The percentage of age-predicted CRF (%age-predicted CRF) is comparable to absolute CRF as a risk indicator for some of these outcomes, but the association between %age-predicted CRF and risk of type 2 diabetes (T2D) has not been previously investigated. We aimed to assess the association between %age-predicted CRF and T2D in a prospective cohort study.

METHODS

Cardiorespiratory fitness, as measured directly by peak oxygen uptake, was assessed in 1901 men aged 42-60 yr who underwent cardiopulmonary exercise testing. The age-predicted CRF estimated from a regression equation for age was converted to %age-predicted CRF using (achieved CRF/age-predicted CRF) × 100. Hazard ratios (95% CI) were estimated for T2D.

RESULTS

During a median follow-up of 26.8 yr, 227 T2D cases were recorded. The risk of T2D decreased continuously with increasing %age-predicted CRF ( P value for nonlinearity = .30). A 1-SD increase in %age-predicted CRF was associated with a decreased risk of T2D in analysis adjusted for established risk factors (HR = 0.68: 95% CI, 0.59-0.79). The corresponding adjusted risk was (HR = 0.51: 95% CI, 0.35-0.75) comparing extreme tertiles of %age-predicted CRF. The respective estimates for the association between absolute CRF and T2D were-HR (95% CI)-0.71 (0.60-0.83) and 0.64 (0.44-0.95).

CONCLUSIONS

Percentage of age-predicted CRF is linearly, inversely, and independently associated with the risk of incident T2D and may be a stronger risk indicator for T2D compared to absolute CRF in a general population of middle-aged and older men.

The interplay among body weight, blood pressure, and cardiorespiratory fitness in predicting atrial fibrillation

BACKGROUND

Hypertension, obesity, and low cardiorespiratory fitness (CRF) are known risk predictors for the development of atrial fibrillation (AF) that often interrelate with each other. We examined the interplay of these 3 risk indicators with the occurrence of AF in patients without known cardiovascular disease.

METHODS

A retrospective analysis of 13,042 patients underwent exercise stress testing (EST). The occurrence of AF during the median follow-up period of 6.8 years was investigated in relation to the presence of obesity (body mass index ≥30 kg/m²), hypertension (blood pressure ≥140/90 mmHg or history of hypertension), or low CRF (exercise capacity <8 metabolic equivalents). Cox proportional hazards models were used to evaluate the individual and combined association between the 3 risk indicators and AF.

RESULTS

The mean age of the study population was 58 ± 9 years; 49% were women. AF occurred in 499 patients (3.8%). Obesity [hazard ratio (95% confidence interval)], 1.36 (1.12-1.65), hypertension, 1.47 (1.19-1.82), and low CRF, 1.32 (1.06-1.64), were independent risk predictors for AF after multivariable adjustment, including after adjusting for each other and also when the risk predictors were analyzed as continuous variables. In a combined model, a gradual increase in the risk of AF was observed, reaching an adjusted hazard ratio of 2.53 (1.77-3.62) in those with all 3 compared with neither risk indicators. P-for-interaction between hypertension and obesity, or hypertension and low CRF was nonsignificant.

CONCLUSIONS

Obesity, low CRF, and hypertension are independently associated with an excess risk of developing AF in patients without known cardiovascular disease, both individually and more so when coexisting together.

Impaired Left Ventricular Contractile Reserve in Patients With Hypertrophic Cardiomyopathy and Abnormal Blood Pressure Response: A Stress Echocardiographic Study

BACKGROUND

Abnormal blood pressure response (ABPR) has been reported to be a risk factor for sudden cardiac death in patients with hypertrophic cardiomyopathy (HCM). We aimed to elucidate the relationship between ABPR during exercise stress echocardiography (ESE) and impaired left ventricular (LV) contractile reserve based on two-dimensional strain in patients with HCM.

METHODS

Patients with HCM underwent ESE with treadmill exercise. Patients whose blood pressure elevation at maximum workload was lower than 20 mmHg from baseline were classified as having ABPR. Echocardiographic parameters were compared between patients with and without ABPR.  Results: Of 26 patients with HCM, nine patients were diagnosed with ABPR. Significant LV outflow tract obstruction (>50 mmHg) was provoked only in one patient with ABPR (baseline to the conclusion of the exercise, 15.2 mmHg to 63.0 mmHg). Change in cardiac output (CO) and the ratio of early diastolic velocity to early annular velocity (E/e') from baseline to just after the conclusion of exercise did not differ between patients with and without ABPR (CO, 102±40% vs. 122±45%, P = 0.19; E/e', 4±22% vs. 2±20%, P = 0.86). Change in systemic vascular resistance change was not significant (patients with vs. without ABPR, -52±10% vs. -46±13%, P = 0.24). Percent change in LV global longitudinal strain was lower in patients with ABPR than patients without ABPR (12±17% vs. 27±15%, P = 0.02).

CONCLUSION

In conclusion, impaired LV contractile reserve during exercise might contribute to ABPR in patients with HCM.

Heart Failure With Preserved Ejection Fraction as an Exercise Deficiency Syndrome: JACC Focus Seminar 2/4

Across differing spectrums of cardiac function and cardiac pathologies, there are strong associations between measures of cardiorespiratory fitness and burden of symptoms, quality of life, and prognosis. In this part 2 of a 4-part series, we contend that there is a strong association among physical activity, cardiorespiratory fitness, and cardiac function. We argue that a chronic lack of exercise is a major risk factor for heart failure with preserved ejection fraction in some patients. In support of this hypothesis, increasing physical activity is associated with greater cardiac mass, greater stroke volumes, greater cardiac output and peak oxygen consumption, and fewer clinical events. Conversely, physical inactivity results in cardiac atrophy, reduced output, reduced chamber size, and decreased ability to augment cardiac performance with exercise. Moreover, physical inactivity is a strong predictor of heart failure risk and death. In sum, exercise deficiency should be considered part of the broad heart failure with preserved ejection fraction phenotype.

Old and new equations for maximal heart rate prediction in patients with heart failure and reduced ejection fraction on beta-blockers treatment: results from the MECKI score data set

AIMS

Predicting maximal heart rate (MHR) in heart failure with reduced ejection fraction (HFrEF) still remains a major concern. In such a context, the Keteyian equation is the only one derived in a HFrEF cohort on optimized β-blockers treatment. Therefore, using the Metabolic Exercise combined with Cardiac and Kidney Indexes (MECKI) data set, we looked for a possible MHR equation, for an external validation of Keteyien formula and, contextually, for accuracy of the historical MHR formulas and their relationship with the HR measured at the anaerobic threshold (AT).

METHODS AND RESULTS

Data from 3487 HFrEF outpatients on optimized β-blockers treatment from the MECKI data set were analyzed. Besides excluding all possible confounders, the new equation was derived by using HR data coming from maximal cardiopulmonary exercise test. The simplified derived equation was [109-(0.5*age) + (0.5*HR rest) + (0.2*LVEF)-(5 if haemoglobin <11 g/dL)]. The R2 and the standard error of the estimate were 0.24 and 17.5 beats min-1 with a mean absolute percentage error (MAPE) = 11.9%. The Keteyian equation had a slightly higher MAPE = 12.3%. Conversely, the Fox and Tanaka equations showed extremely higher MAPE values. The range 75-80% of MHR according to the new and the Keteyian equations was the most accurate in identifying the HR at the AT (MAPEs = 11.3-11.6%).

CONCLUSION

The derived equation to estimate the MHR in HFrEF patients, by accounting also for the systolic dysfunction degree and anaemia, improved slightly the Keteyian formula. Both formulas might be helpful in identifying the true maximal effort during an exercise test and the intensity domain during a rehabilitation programme.

Cardiorespiratory Fitness and Mortality Risk Across the Spectra of Age, Race, and Sex

BACKGROUND

Cardiorespiratory fitness (CRF) is inversely associated with all-cause mortality. However, the association of CRF and mortality risk for different races, women, and elderly individuals has not been fully assessed.

OBJECTIVES

The aim of this study was to evaluate the association of CRF and mortality risk across the spectra of age, race, and sex.

METHODS

A total of 750,302 U.S. veterans aged 30 to 95 years (mean age 61.3 ± 9.8 years) were studied, including septuagenarians (n = 110,637), octogenarians (n = 26,989), African Americans (n = 142,798), Hispanics (n = 35,197), Native Americans (n = 16,050), and women (n = 45,232). Age- and sex-specific CRF categories (quintiles and 98th percentile) were established objectively on the basis of peak METs achieved during a standardized exercise treadmill test. Multivariable Cox models were used to estimate HRs and 95% CIs for mortality across the CRF categories.

RESULTS

During follow-up (median 10.2 years, 7,803,861 person-years of observation), 174,807 subjects died, averaging 22.4 events per 1,000 person-years. The adjusted association of CRF and mortality risk was inverse and graded across the age spectrum, sex, and race. The lowest mortality risk was observed at approximately 14.0 METs for men (HR: 0.24; 95% CI: 0.23-0.25) and women (HR: 0.23; 95% CI: 0.17-0.29), with no evidence of an increase in risk with extremely high CRF. The risk for least fit individuals (20th percentile) was 4-fold higher (HR: 4.09; 95% CI: 3.90-4.20) compared with extremely fit individuals.

CONCLUSIONS

The association of CRF and mortality risk across the age spectrum (including septuagenarians and octogenarians), men, women, and all races was inverse, independent, and graded. No increased risk was observed with extreme fitness. Being unfit carried a greater risk than any of the cardiac risk factors examined.

Trends in the Prevalence and Incidence of Opium Abuse and its Association with Coronary Artery Risk Factors in Adult Population in Iran: Findings from Kerman Coronary Artery Disease Risk Factors Study

BACKGROUND

The prevalence of opium addiction in Iran is high probably due to the belief that opium has preventive effects against cardiovascular diseases. In the second phase of Kerman coronary artery disease risk factors study, the prevalence, incidence rate, and the association between opium use and other coronary artery disease risk factors (CADRFs) were assessed.

METHODS

In a cross-sectional study (2014-2018), 9996 inhabitants of Kerman, southeastern Iran, aged 15-80 years were recruited to the study. After taking fasting blood samples, the participants were examined or interviewed for demographic data and CADRFs, including opium use. The participants were categorized into "never", "occasional", and "dependent" users. The association between opium use and CADRFs was assessed with adjusted regression analysis (Stata v.11 software).

RESULTS

The overall prevalence of opium consumption was lower than that of five years earlier (P<0.01). The prevalence was currently higher in men than women and decreased in men between the two phases (P<0.001). There was a positive correlation between opium use and depression (P<0.001), anxiety (P<0.05), and a negative association with the level of physical activity (P<0.001). The five-year incident rate of dependent and occasional opium use was 4.2 and 3.9 persons/100 person-years, respectively. The incidence of opium use was higher in diabetic, hypertensive, depressed, anxious, and obese subjects.

CONCLUSION

The study did not demonstrate any protective effects of opium on CADRFs. Considering the higher rate of opium use in subjects with hypertension, diabetes, obesity, and psychological disorders, the health authorities should implement educational programs to warn and correct the unsafe belief.

Heart Rate Response to Exercise and Recovery: INDEPENDENT PROGNOSTIC MEASURES IN PATIENTS WITHOUT KNOWN MAJOR CARDIOVASCULAR DISEASE

PURPOSE

Heart rate response during exercise testing (ET) provides valuable prognostic information. Limited data are available regarding the prognostic interplay of heart rate (HR) measured at rest, exercise and recovery phases of ET, and its ability to predict risk beyond exercise capacity.

METHODS

Retrospective analysis of treadmill ETs was performed by the Bruce protocol in patients aged 35-75 yr without known cardiovascular disease (CVD; n = 13 887; 47% women). Heart rate recovery at 2 min (HRR2; defined abnormal <42 beats) and chronotropic index (CI; defined abnormal <80%, determined as age-predicted HR reserve) were analyzed in association with the risk of developing myocardial infarction, stroke, or death (major adverse cardiovascular event [MACE]) during median follow-up of 6.5 yr.

RESULTS

The HRR2 <42 beats and CI <80% were each associated with increased risk of MACE: adjusted hazard ratios with 95% confidence interval 1.47: 1.27-1.72 and 1.66: 1.42-1.93, P < .001, respectively, evident also when analyzed as continuous variables. Strength of association of HRR2 and CI with outcome was attenuated but remained significant with further adjustment for exercise duration and metabolic equivalents. Having both HRR2 and CI abnormal compared with only one measure abnormal was associated with hazard ratios with 95% confidence interval of 1.66: 1.38-2.00 and 1.48: 1.22-1.79 for MACE, before and after adjustment for cardiorespiratory fitness (CRF). The degree of CRF (low vs mid/high) did not modify the prognostic effect of HRR2 and CI (P-for-interaction nonsignificant).

CONCLUSIONS

Both HRR2 and CI provide independent prognostic information beyond CRF in patients without CVD referred for ET. The predictive ability is more pronounced when both abnormal HR measures coexist.

Prognostic Utility of a New Risk Stratification Protocol for Secondary Prevention in Patients Attending Cardiac Rehabilitation

Several risk scores have been used to predict risk after an acute coronary syndrome (ACS), but none of these risk scores include functional class. The aim was to assess the predictive value of risk stratification (RS), including functional class, and how cardiac rehabilitation (CR) changed RS. Two hundred and thirty-eight patients with ACS from an ambispective observational registry were stratified as low (L) and no-low (NL) risk and classified according to exercise compliance; low risk and exercise (L-E), low risk and control (no exercise) (L-C), no-low risk and exercise (NL-E), and no-low risk and control (NL-C). The primary endpoint was cardiac rehospitalization. Multivariable analysis was performed to identify variables independently associated with the primary endpoint. The L group included 56.7% of patients. The primary endpoint was higher in the NL group (18.4% vs. 4.4%, p < 0.001). After adjustment for age, sex, diabetes, and exercise in multivariable analysis, HR (95% CI) was 3.83 (1.51−9.68) for cardiac rehospitalization. For RS and exercise, the prognosis varied: the L-E group had a cardiac rehospitalization rate of 2.5% compared to 26.1% in the NL-C group (p < 0.001). Completing exercise training was associated with reclassification to low-risk, associated with a better outcome. This easy-to-calculate risk score offers robust prognostic information. No-exercise groups were independently associated with the worst outcomes. Exercise-based CR program changed RS, improving classification and prognosis.

Percentage of Age-Predicted Cardiorespiratory Fitness and Risk of Incident Hypertension: A PROSPECTIVE COHORT STUDY

PURPOSE

There are inverse and independent associations between cardiorespiratory fitness (CRF) and several adverse cardiometabolic outcomes including hypertension (HTN). The prospective relationship between percentage of age-predicted CRF and risk of HTN has not been previously investigated. We aimed to assess the association of percentage of age-predicted CRF with incident HTN in a long-term prospective cohort study.

METHODS

Cardiorespiratory fitness, as measured by peak oxygen uptake, was assessed using the gold standard respiratory gas exchange analyzer in 1602 men who underwent cardiopulmonary exercise testing. The age-predicted CRF estimated from a regression equation for age was converted to percentage of age-predicted CRF ([achieved CRF/age-predicted CRF] × 100). The HR with 95% CI were estimated for HTN.

RESULTS

During a median follow-up of 26.8 yr, 308 HTN cases were recorded. There was a linear relationship between age-predicted CRF and incident HTN (P value for nonlinearity = .68). A 1-SD increase in percentage of age-predicted CRF was associated with a decreased risk of HTN in analysis adjusted for established risk factors (HR = 0.79: 95% CI, 0.69-0.90), which remained consistent on further adjustment for several other potential confounders including alcohol consumption, physical activity, socioeconomic status, and inflammation (HR = 0.83: 95% CI, 0.72-0.95). The corresponding adjusted HRs were 0.55 (95% CI, 0.38-0.80) and 0.63 (95% CI, 0.43-0.91), respectively, when comparing extreme quartiles of percentage of age-predicted CRF levels.

CONCLUSIONS

Percentage of age-predicted CRF is linearly, inversely, and independently associated with risk of incident HTN, and it is comparable to absolute CRF as a risk indicator for HTN in a general population of middle-aged men.

Role of Exercise Treadmill Testing in the Assessment of Coronary Microvascular Disease

OBJECTIVES

The authors aimed to study the sensitivity and specificity of exercise treadmill testing (ETT) in the diagnosis of coronary microvascular disease (CMD), as well as the prognostic implications of ETT results in patients with CMD.

BACKGROUND

ETT is validated to evaluate for flow-limiting coronary artery disease (CAD), however, little is known about its use for evaluating CMD.

METHODS

We retrospectively studied 249 consecutive patients between 2006 and 2016 who underwent ETT and positron emission tomography within 12 months. Patients with obstructive CAD or left ventricular systolic dysfunction were excluded. CMD was defined as a coronary flow reserve <2. Patients were followed for the occurrence of a first major adverse event (composite of death or hospitalization for myocardial infarction or heart failure).

RESULTS

The sensitivity and specificity of a positive ETT to detect CMD were 34.7% (95% CI: 25.4%-45.0%) and 64.9% (95% CI: 56.7%-72.5%), respectively. The specificity of a positive ETT to detect CMD increased to 86.8% (95% CI: 80.3%-91.7%) when only classifying studies with ischemic electrocardiogram changes that lasted at least 1 minute into recovery as positive, although at a cost of lower sensitivity (15.3%; 95% CI: 8.8%-24.0%). Over a median follow-up of 6.9 years (IQR: 5.1-8.2 years), 30 (12.1%) patients met the composite endpoint, including 13 (13.3%) with CMD (n = 98). In patients with CMD, ETT result was not associated with the composite endpoint (P = 0.076).

CONCLUSIONS

Our data suggest limited sensitivity of ETT to detect CMD. However, a positive ETT with ischemic changes that persist at least 1 minute into recovery in the absence of obstructive CAD should raise suspicion for the presence of CMD given a high specificity. Further study is needed with larger patient sample sizes to assess the association between ETT results and outcomes in patients with CMD.

Average Exercise Capacity in Men and Women >75 Years of Age Undergoing a Bruce Protocol Exercise Stress Test

Exercise stress testing is routinely performed to evaluate suspected coronary artery disease in older adults. However, the available data to predict and compare relative exercise capacity in the general population were developed using predominantly younger, healthy cohorts with few or no women. This study aimed to describe the exercise capacity of patients older than 75 years who underwent a clinically indicated Bruce protocol exercise stress test. This was a retrospective, cross-sectional study of 2,041 consecutive patients older than 75 years who performed a Bruce protocol exercise stress echocardiogram that was terminated because of maximal effort without ischemia at Columbia University Medical Center between April 10, 2009, and July 30, 2020. The analytic sample included 2,041 exercise stress tests in 786 women (median [interquartile range] age 79 [77 to 81] years) and 1,255 men (median [interquartile range] age 79 [77 to 82] years). Cardiovascular risk factors and clinical coronary disease were common and more prevalent in men than women. The median exercise time for men aged 76 to 80 years was 7:22 (minutes:seconds) and for women was 6:00 and significantly decreased in both genders as age increased (p <0.001). The mean (SD) METs achieved for women and men were 6.5 (1.6) and 7.7 (1.7), respectively. Most women (85%) and men (95%) completed the first stage, whereas only 32% of women and 64% of men completed the second stage. It was uncommon for women (3%) or men (15%) to complete the third stage. Fewer than 1% of patients completed the fourth stage, and none completed the fifth stage. At all ages, women had a lower exercise capacity than men. These data allow physicians to compare the exercise capacity of older patients who underwent a Bruce protocol exercise stress test more accurately to a representative sample of similarly aged adults.

Sex related differences in exercise performance in patients with hypertrophic cardiomyopathy: Hemodynamic insights through non-invasive pressure volume analysis

BACKGROUND

Women with HCM have worse cardiopulmonary exercise performance compared to men. We used non-invasive pressure-volume (PV) analysis to delineate sex related hemodynamic differences in HCM.

METHODS

PV loops were constructed from echocardiograms using left ventricular (LV) volumes indexed to body surface area, Doppler estimates of LV end-diastolic pressure and blood pressure. The end-systolic PV relationship (ESPVR) and end-diastolic PV relationship (EDPVR) were derived from validated single-beat techniques. The area between the ESPVR and EDPVR (isovolumetric PV area), was indexed to an LV end-diastolic pressure of 30 mmHg (PVA_iso30), as the integrated metric of LV function. LV volume at an end-diastolic pressure of 30 mmHg (V30) indexed ventricular capacity.

RESULTS

202 patients were included, 56 women. Women were older (51 vs 44 years, p = 0.012) and had reduced exercise capacity (5.6 vs 6.9 METs, p < 0.001). Only 32 patients (16%) had a peak gradient >30 mmHg at rest with no sex differences. Women had significantly lower indexed PVA_iso30 (9094 vs 10,255 mmHg*mL/m², p = 0.02) driven by reduced ventricular capacitance (V30 54 vs 62 mL/m², p < 0.001). In multivariable linear regression indexed V30 was an independent predictor of exercise capacity.

CONCLUSION

Impaired exercise capacity in women with HCM appears associated with abnormalities in passive diastolic properties, suggesting a unique pathophysiology compared to men, and a potential difference in viable therapeutic molecular targets.

Cardiorespiratory optimal point during exercise testing and sudden cardiac death: A prospective cohort study

BACKGROUND

Cardiorespiratory optimal point (COP) during exercise, a potentially useful submaximal cardiopulmonary exercise testing (CPET) variable, may be an independent risk factor for cardiovascular disease outcomes. However, the relationship of COP with risk of sudden cardiac death (SCD) has not been previously investigated. We sought to evaluate the association between COP during exercise and SCD risk and determine whether COP improves SCD risk prediction.

METHODS

COP, the minimum value of the ventilatory equivalent for oxygen (VE/VO2) in a given minute of a CPET, was ascertained in 2190 men who underwent clinical exercise testing. Hazard ratios (HRs) (95% confidence intervals [CIs]) and measures of risk discrimination for SCD were calculated.

RESULTS

A total of 240 SCDs death occurred during a median follow-up of 28.8 years. COP was linearly associated with SCD in a dose-response manner. In a multivariable model comprising several established and emerging CVD risk factors, the HR (95% CI) for SCD was 2.51 (1.36-4.62) per standard deviation increase in COP. This was minimally attenuated to 2.36 (1.27-4.37) on further adjustment for high sensitivity C-reactive protein. The association did not vary importantly in several relevant clinical subgroups. Addition of COP to a SCD risk score was associated with a C-index change of 0.0086 (0.0005 to 0.0167; p = .038) and difference in -2 log likelihood (p = .017).

CONCLUSIONS

COP during exercise is strongly, inversely and independently associated with SCD in a graded fashion. COP during exercise may potentially be used for the prediction of the long-term risk for SCD beyond established CVD risk factors.

Associations between cardiorespiratory fitness, sex and long term mortality amongst adults undergoing exercise treadmill testing

BACKGROUND

Cardiorespiratory fitness (CRF) varies with sex and is an independent predictor of mortality. We sought to investigate sex differences in the exercise protocol selected, CRF levels, and their relationships with long term all-cause mortality.

METHODS

In a 25-year stress testing registry spanning from 1991 to 2014, consecutive all-comer patients who underwent exercise stress testing at Cleveland Clinic were categorized by sex, stress protocol and imaging modality. All tests were conducted by one or more of stress test technicians, sonographers and nuclear medicine technologists, and interpreted by cardiologists. The primary outcome all-cause mortality was analyzed in using multivariable Cox regression.

RESULTS

In 120,705 patients, the mean age was 53.3 ± 12.5 years, and 41% were female. Females were more commonly referred for non-Bruce exercise protocols (modified Bruce, Cornell 0, 5 and 10, Naughton and modified Naughton) with odds ratio of 2.62; 95% confidence interval (95%CI) (2.54-2.70) after adjusting for age and comorbidities. When also adjusting for the protocol chosen, females achieved lower CRF with beta -1.40, 95% CI (-1.43, -1.37). There were 8426 (6.9%) deaths during a mean follow-up of 8.7 years. Both female sex and CRF were independently associated with lower all-cause mortality with hazards ratio (95%CI) of 0.44 (0.41-0.46) and 0.41 (0.39-0.42) respectively, after adjusting for age, co-morbidities and protocol chosen.

CONCLUSIONS

Women were more likely referred for less demanding exercise protocols, more imaging protocols and achieved lower CRF than men. Despite this, female sex was associated with significantly lower long term mortality for equivalent CRF level in adjusted analyses.

Percentage of Age-Predicted Cardiorespiratory Fitness Is Inversely Associated with Cardiovascular Disease Mortality: A Prospective Cohort Study

INTRODUCTION

Percentage of age-predicted cardiorespiratory fitness (% age-predicted CRF) is a potentially useful cardiopulmonary exercise testing (CPX) parameter, but there are limited data on its prognostic relevance for adverse cardiovascular disease (CVD) outcomes. We aimed to assess the association of % age-predicted CRF with CVD mortality and the extent to which % age-predicted CRF measurements could improve the prediction of CVD mortality.

METHODS

Peak oxygen uptake, used as the measure of CRF, was directly assessed in 2,276 men who underwent CPX. The age-predicted CRF estimated from a regression equation for age was transformed to % age-predicted CRF with the following formula: (achieved CRF/age-predicted CRF) × 100. Hazard ratios (HRs) (95% confidence intervals [CIs]) and measures of risk discrimination for CVD mortality were calculated.

RESULTS

During a median follow-up of 28.5 years, 643 fatal CVDs were recorded. The relationship between % age-predicted CRF and CVD mortality was dose response in nature. In analysis adjusted for conventional risk factors, one standard deviation increase in % age-predicted CRF was associated with a reduced risk of CVD mortality (HR 0.61; 95% CI: 0.56-0.67), which was minimally attenuated on further adjustment for several other confounders (HR 0.71; 95% CI: 0.64-0.78). Addition of % age-predicted CRF to a CVD mortality risk prediction model containing established risk factors significantly improved risk discrimination and reclassification.

CONCLUSION

Percentage of age-predicted CRF is inversely and independently associated with CVD mortality in a graded fashion and significantly improves the prediction and classification of the long-term risk for CVD mortality beyond established risk factors.

Cardiorespiratory optimal point during exercise testing is related to cardiovascular and all-cause mortality

Cardiorespiratory optimal point (COP) during exercise may be a potentially clinically useful cardiopulmonary exercise testing (CPET) variable, but its prognostic relevance for adverse cardiovascular disease (CVD) outcomes is unknown. We aimed to assess the association of COP during exercise with fatal mortality outcomes and the extent to which COP could improve the prediction of CVD mortality. Cardiorespiratory optimal point, the minimum value of the ventilatory equivalent for oxygen (VE/VO2) in a given minute of a CPET, was defined in 2,205 men who underwent CPET. Hazard ratios (HRs) (95% confidence intervals [CIs]) for outcomes and measures of risk discrimination for CVD mortality were calculated. During a median follow-up of 28.8 years, 402 fatal CHDs, 607 fatal CVDs, and 1,348 all-cause mortality events occurred. COP was continually associated with each outcome in a dose-response manner. On adjustment for established and emerging risk factors, the HRs (95% CIs) for fatal CHD, fatal CVD, and all-cause mortality were 3.05 (1.94-4.81), 2.82 (1.91-4.18) and 2.46 (1.85-3.27), respectively, per standard deviation increase in COP. After further adjustment for high sensitivity C-reactive protein, the HRs were 2.82 (1.78-4.46), 2.57 (1.73-3.81), and 2.27 (1.70-3.02), respectively. Addition of COP to a CVD mortality risk prediction model containing established risk factors was associated with a C-index change of 0.0139 (0.0040 to 0.0238; p = 0.006) at 25 years. COP during exercise is directly associated with fatal cardiovascular and all-cause mortality events in dose-response fashions. COP during exercise may improve the prediction of the long-term risk for CVD mortality.

Incremental value of diastolic stress test in identifying subclinical heart failure in patients with diabetes mellitus

AIMS

Resting echocardiography is a valuable method for detecting subclinical heart failure (HF) in patients with diabetes mellitus (DM). However, few studies have assessed the incremental value of diastolic stress for detecting subclinical HF in this population.

METHODS AND RESULTS

Asymptomatic patients with Type 2 DM were prospectively enrolled. Subclinical HF was assessed using systolic dysfunction (left ventricular longitudinal strain <16% at rest and <19% after exercise in absolute value), abnormal cardiac morphology, or diastolic dysfunction (E/e' > 10). Metabolic equivalents (METs) were calculated using treadmill speed and grade, and functional capacity was assessed by percent-predicted METs (ppMETs). Among 161 patients studied (mean age of 59 ± 11 years and 57% male sex), subclinical HF was observed in 68% at rest and in 79% with exercise. Among characteristics, diastolic stress had the highest yield in improving detection of HF with 57% of abnormal cases after exercise and 45% at rest. Patients with revealed diastolic dysfunction during stress had significantly lower exercise capacity than patients with normal diastolic stress (7.3 ± 2.1 vs. 8.8 ± 2.5, P < 0.001 for peak METs and 91 ± 30% vs. 105 ± 30%, P = 0.04 for ppMETs). On multivariable modelling found that age (beta = -0.33), male sex (beta = 0.21), body mass index (beta = -0.49), and exercise E/e' >10 (beta = -0.17) were independently associated with peak METs (combined R2 = 0.46). A network correlation map revealed the connectivity of peak METs and diastolic properties as central features in patients with DM.

CONCLUSION

Diastolic stress test improves the detection of subclinical HF in patients with diabetes mellitus.

Percentage of age-predicted cardiorespiratory fitness and risk of sudden cardiac death: A prospective cohort study

BACKGROUND

The inverse associations between cardiorespiratory fitness (CRF) and vascular outcomes have been established. However, there has been no prospective evaluation of the relationship between percentage of age-predicted cardiorespiratory fitness (%age-predicted CRF) and risk of sudden cardiac death (SCD).

OBJECTIVE

The purpose of this study was to assess the association of %age-predicted CRF with SCD risk in a long-term prospective cohort study.

METHODS

CRF was assessed using the gold standard respiratory gas exchange analyzer in 2276 men who underwent cardiopulmonary exercise testing. The age-predicted CRF estimated from a regression equation for age was converted to %age-predicted CRF using (Achieved CRF/Age-predicted CRF) × 100. Hazard ratios (HRs) [95% confidence intervals (CIs)] were calculated for SCD.

RESULTS

During median follow-up of 28.2 years, 260 SCDs occurred. There was a dose-response relationship between age-predicted CRF and SCD. A 1-SD increase in %age-predicted CRF was associated with a decreased risk of SCD in analysis adjusted for established risk factors (HR 0.60; 95% CI 0.53-0.70), which remained consistent on further adjustment for several potential confounders, including alcohol consumption, physical activity, socioeconomic status, and systemic inflammation (HR 0.73; 95% CI 0.62-0.85). The corresponding adjusted HRs were 0.34 (0.23-0.50) and 0.52 (0.34-0.79), respectively, when comparing extreme quartiles of %age-predicted CRF levels. HRs for the associations of absolute CRF levels with SCD risk in the same participants were similar.

CONCLUSION

Percentage of age-predicted CRF is continuously, strongly, and independently associated with risk of SCD and is comparable to absolute CRF as a risk indicator for SCD.

Association of metabolic equivalent of task (MET) score in length of stay in hospital following radical cystectomy with urinary diversion: a multi-institutional study

PURPOSE

The Metabolic equivalent of task (MET) score is used in patients' preoperative functional capacity assessment. It is commonly thought that patients with a higher MET score will have better postoperative outcomes than patients with a lower MET score. However, such a link remains the subject of debate and is yet unvalidated in major urological surgery. This study aimed to explore the association of patients' MET score with their postoperative outcomes following radical cystectomy.

METHODS

We used records-linkage methodology with unique identifiers (Community Health Index/hospital number) and electronic databases to assess postoperative outcomes of patients who had underwent radical cystectomies between 2015 and 2020. The outcome measure was patients' length of hospital stay. This was compared with multiple basic characteristics such as age, sex, MET score and comorbid conditions. A MET score of less than four (< 4) is taken as the threshold for a poor functional capacity. We conducted unadjusted and adjusted Cox regression analyses for time to discharge against MET score.

RESULTS

A total of 126 patients were included in the analysis. Mean age on date of operation was 66.2 (SD 12.2) years and 49 (38.9%) were female. A lower MET score was associated with a statistically significant lower time-dependent risk of hospital discharge (i.e. longer hospital stay) when adjusted for covariates (HR 0.224; 95% CI 0.077-0.652; p = 0.006). Older age (adjusted HR 0.531; 95% CI 0.332-0.848; p = 0.008) and postoperative complications (adjusted HR 0.503; 95% CI 0.323-0.848; p = 0.002) were also found to be associated with longer hospital stay. Other comorbid conditions, BMI, disease staging and 30-day all-cause mortality were statistically insignificant.

CONCLUSION

A lower MET score in this cohort of patients was associated with a longer hospital stay length following radical cystectomy with urinary diversion.

Prolonged Elevation of Tricuspid Regurgitation Pressure Gradient After Exercise in Patients With Exercise-induced Pulmonary Hypertension

It is necessary to measure the peak tricuspid regurgitation pressure gradient (TRPG) that is recorded at maximum exercise intensity when diagnosing exercise-induced pulmonary hypertension (ePH) on exercise stress echocardiography (ESE). However, it is difficult to measure maximum TRPG during the treadmill exercise. If ePH induced TRPG elevation continues during recovery period after exercise termination, this elevation will serve as a practical diagnostic standard. We aimed to assess whether the elevation of postexercise peak TRPG prolong soon after finishing exercise in patients with ePH. Seventy-four patients underwent symptom-limited ESE by using a semirecumbent bicycle ergometer. ePH was defined as peak TRPG > 50 mm Hg at maximum exercise. We measured peak TRPG during exercise and until 5 minutes afterward. Thirty-five patients were diagnosed with ePH; their median TRPG was 57 mm Hg [interquartile range: 52-62 mm Hg] at maximum exercise. Peak TRPG in patients with ePH was > 40 mm Hg until 2 minutes after exercise. The cut-off values of peak TRPG to detect ePH were 43 mm Hg just after exercise and 41 mm Hg at 1 minute afterward (areas under the curve: 0.98, 0.92, respectively; both p < 0.001). In conclusion, elevated peak TRPG persisted for at least 2 minutes after finishing exercise, and this time frame will therefore provide a new window for diagnosing ePH by ESE.

Aerobic exercise and inspiratory muscle training increase functional capacity in patients with univentricular physiology after Fontan operation: A randomized controlled trial

BACKGROUND

The effect of exercise training and its mechanisms on the functional capacity improvement in Fontan patients (FP) are virtually unknown. This trial evaluated four-month aerobic exercise training and inspiratory muscle training on functional capacity, pulmonary function, and autonomic control in patients after Fontan operation.

METHODS

A randomized controlled clinical trial with 42 FP aged 12 to 30 years and, at least, five years of Fontan completion. Twenty-seven were referred to a four-months supervised and personalized aerobic exercise training (AET) or an inspiratory muscle training (IMT). A group of non-exercise (NET) was used as control. The effects of the exercise training in peak VO₂; pulmonary volumes and capacities, maximal inspiratory pressure (MIP); muscle sympathetic nerve activity (MSNA); forearm blood flow (FBF); handgrip strength and cross-sectional area of the thigh were analyzed.

RESULTS

The AET decreased MSNA (p = 0.042), increased FBF (p = 0.012) and handgrip strength (p = 0.017). No significant changes in autonomic control were found in IMT and NET groups. Both AET and IMT increased peak VO2, but the increase was higher in the AET group compared to IMT (23% vs. 9%). No difference was found in the NET group. IMT group showed a 58% increase in MIP (p = 0.008) in forced vital capacity (p = 0.011) and forced expiratory volume in the first second (p = 0.011). No difference in pulmonary function was found in the AET group.

CONCLUSIONS

Both aerobic exercise and inspiratory muscle training improved functional capacity. The AET group developed autonomic control, and handgrip strength, and the IMT increased inspiratory muscle strength and spirometry.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02283255.

Nomograms based on pre-operative parametric for prediction of short-term mortality in acute myocardial infarction patients treated invasively

Objective Our aim was to develop and independently validate nomograms to predict short-term mortality in acute myocardial infarction (AMI) patients.

Results There were 1229 AMI patients enrolled in this study. In the training cohort (n=534), 69 deaths occurred during a median follow-up period of 375 days. The C-index for 1-year mortality in the training group and the validation cohort was 0.826 (95%CI: 0.780 - 0.872) and 0.775 (95%CI: 0.695 - 0.855), respectively. Integrated Discrimination Improvement (IDI) and net reclassification improvement (NRI) also showed a significant improvement in the accuracy of the new model compared with the Global Registry of Acute Coronary Events (GRACE) risk score. Furthermore, C-index of the prospective cohort (n=309) achieved 0.817 (95%CI: 0.754 - 0.880) for 30-day mortality and 0.790 (95%CI: 0.718 - 0.863) for 1-year mortality.

Conclusions Collectively, our simple-to-use nomogram effectively predicts short-term mortality in AMI patients.

Methods AMI patients who had undergone invasive intervention between January 2013 and Jan 2018 were enrolled. Cox regression analysis was used on the training cohort to develop nomograms for predicting 30-day and 1-year mortality. Model performance was then evaluated in the validation cohort and another independent prospective cohort.

Prognostic Value of Functional Capacity in Different Exercise Protocols

Background

Functional capacity is associated with mortality, although the prognostic value of achieved estimated metabolic equivalents (METs) across various exercise protocols is not established. We sought to determine whether achieved METs had different prognostic implications according to the protocol employed.

Methods and Results

From 1991 to 2015, we identified 120 705 consecutive patients from a stress testing registry who underwent the following 7 different standardized exercise protocols: Bruce, modified Bruce, Cornell 0%, Cornell 5%, Cornell 10%, Naughton, and modified Naughton. The primary outcome was all‐cause mortality. There were 74 953 Bruce, 8368 modified Bruce, 2648 Cornell 0%, 9972 Cornell 5%, 20 425 Cornell 10%, 1226 Naughton, and 3113 modified Naughton protocols. During a mean follow‐up of 8.7 years, a total of 8426 deaths (6.9%) occurred. When compared with the Bruce protocol, after multivariable adjustment for clinical risk factors, medications, and functional capacity, test protocol was independently associated with mortality (modified Naughton [hazard ratio (HR), 2.51; 95% CI, 2.26–2.8], Naughton [HR, 1.79; 95% CI, 1.57–2.04], Cornell 0% [HR, 1.79; 95% CI, 1.59–2.01], modified Bruce [HR, 1.62; 95% CI, 1.48–1.76], Cornell 5% [HR, 1.61; 95% CI, 1.47–1.75], and Cornell 10% [HR, 1.32; 95% CI, 1.22–1.42]). Across all protocols, higher estimated METs were associated with lower mortality, although the equivalent METs achieved were associated with a worse prognosis in less‐demanding protocols.

Conclusions

Higher estimated METs are reliably associated with lower mortality in all exercise protocols, although the prognostic value is not transferable across different tests. Consequently, the prognostic value of METs achieved during a stress test should be considered protocol dependent.

Relationship of left atrial expansion index to exercise tolerance, pretest probability of restenosis, and positive predictive value of treadmill test in coronary artery disease

BACKGROUND

Whether left atrial (LA) expansion index is associated with coronary restenosis, and exercise capacity (EC) reduction in coronary artery disease has not been established.

METHODS

This study analyzed 342 consecutive patients who had received a coronary stent implant. A treadmill exercise test (TET) was administered in all participants. The LA expansion indices were measured immediately before and after TET. Maximal EC measured on a breath-by-breath basis by a metabolic cart with gas analyzers and recorded as metabolic equivalent task. All patients with positive TET results received angiography, and those with restenosis received complete revascularization by either percutaneous coronary intervention (PCI) or bypass surgery. The LA expansion index and EC before and 1 month after PCI were then compared.

RESULTS

Out of 342 patients, 74 had positive TET results, and 54 had restenosis in angiography. Low LA expansion index was associated with poor EC. In patients with LA expansion index > 200%, only 5% had restenosis with 38.5% positive predictive value (PPV) of TET. In patients with LA expansion index < 100%, however, 64.3% had restenosis with 94.7% PPV of TET. Restenosis induced low pre-TET LA expansion index and further decline during TET. The LA expansion index significantly (P .001) improved from 133 ± 64% before PCI to184 ± 86% after PCI, and the improvement corresponded with EC recovery. A 10% reduction in LA expansion index was associated with a 15% increase in pretest probability of restenosis.

CONCLUSION

The LA expansion index is associated with EC, pretest probability of restenosis, and PPV of TET. Revascularization improves both EC and LA expansion index.

Survival of the Fittest: Impact of Cardiorespiratory Fitness on Outcomes in Men and Women with Cardiovascular Disease

Cardiovascular disease (CVD) in general and myocardial infarction in particular are the leading causes of mortality in men and women globally. Sex differences in CVD recovery exist, with higher rates of mortality, recurrent myocardial infarction, and poor functional outcomes seen in women compared to men with CVD. Physical inactivity has been identified as a crucial modifiable risk factor linked with poor survival and recovery in patients with CVD. Cardiac rehabilitation programs that aim to improve physical inactivity and cardiorespiratory fitness (CRF), a measure of physical fitness in patients with CVD, have gained popularity. The goals of this commentary were to summarize the existing literature on the impact of CRF on survival in patients with CVD, to document the impact of sex on CVD outcomes, and to highlight any gaps in current knowledge. Even minor improvements in CRF have been linked with improved survival, although contemporary data from randomized controlled trials have shown mixed results. Gender differences in cardiac rehabilitation have been well documented, with lower referral, enrollment, and completion rates noted in women compared to men with CVD. However, data on sex differences in CRF with cardiac rehabilitation are scant, mostly indicating lower peak CRF observed in female compared to male patients on completion. It is unclear whether similar thresholds of peak CRF are needed in male and female patients to improve survival after onset of CVD, and whether exercise prescriptions need to be adapted to include additional forms of exercise. CRF is also influenced by age, with a decline in peak exercise capacity with advancing age observed in both sexes, but steeper declines noted in men than women. From this perspective, we review the data intersecting age, sex, and exercise on survival in patients with CVD, as well as the biological mechanisms at play, and we identify areas for future research (Clin Ther. 2020; 42:XXX-XXX) © 2020 Elsevier Inc.

Physiological and biomechanical comparison between electrically assisted bicycles and motorbikes during simulated mail delivery

Electrically assisted bicycles (EABs) and motorbikes were compared in terms of energy expenditure, internal and external forces, and technique when delivering mail with different loads at different distances from the mailbox. Twenty-two postal workers performed two simulated postal tasks (foot placement [close vs. far] and delivery, and simulated mail delivery circuit) while carrying 0 and 32 kg. Independent of mail load, delivering mail with EABs was classified as moderate intensity and resulted in 33% higher energy expenditure when compared to motorbikes. Ground reaction forces were larger (7-25%) for EAB when compared to motorbike. Larger ground reaction forces were observed when both EABs and motorbikes were positioned further from the mailbox (5-23%). Using EABs during mail delivery has potential to result in numerous health benefits that are associated with moderate intensity physical activity, but can lead to larger external forces when compared to motorbikes. Practitioner summary: In order to compare electrically assisted bicycles (EAB) and motorbikes, postal workers performed simulated deliveries in the laboratory whilst measurements of energy expenditure, body loads and movement patters were undertaken. Body loads and energy expenditure were larger using EAB, which result in health benefits associated with moderate intensity exercise. Abbreviations: EAB: electrically assisted bicycles; CI: confidence interval; UHEC: University Human Ethics Committee; MB: motorbike;SH: seat height; SF: seat to floor distance; VO2: oxygen uptake; VCO2: exhaled carbon dioxide; RER: respiratory exchangeratio; TTL signal: Transistor-Transistor Logic; MET: metabolic equivalent; 3D: three-dimensional; IIR: infinite impulse response; Hz:Hertz; N: Newtons; ROM: range of motion; SD: standard deviation; p: significance level; d: Cohen effect sizes.

Abnormal Exercise Test or CVD History on Weight Loss or Fitness: the Look AHEAD Trial

PURPOSE

Obesity and type 2 diabetes are associated with an increased risk of cardiovascular disease (CVD) and the combination of weight loss and increased physical exercise are commonly recommended to reduce CVD. This study examined whether people with obesity and type 2 diabetes with an abnormal graded exercise tolerance test (GXT) or a history of CVD would have less success in achieving weight loss and improved fitness, compared to adults without these conditions.

METHODS

The Look AHEAD Study examined whether an intensive lifestyle intervention (ILI) compared with diabetes support and education (DSE) reduced cardiovascular events in adults with overweight/obesity and type 2 diabetes. Participants underwent a baseline maximal GXT and provided medical history data. Weight loss and fitness change were examined in 5011 participants over four years in those with or without an abnormal baseline GXT and/or history of CVD.

RESULTS

After four years, weight loss in both ILI and DSE were significantly greater in those without a prior history of CVD than in those with a CVD history (6.69% vs 5.98%, p=0.02, in ILI and 0.73 vs -.07% (weight gain), p=0.01, in DSE). Likewise, those without a prior history of CVD experienced greater improvements in fitness in both ILI and DSE relative to those with a history of CVD. Having an abnormal GXT at baseline did not affect weight loss or fitness.

CONCLUSIONS

A history of CVD at baseline modestly lessened weight loss and fitness changes at 4 years, whereas having any abnormality on the baseline GXT did not affect these outcomes. Thus, weight loss and improved fitness are achievable in adults with a history of CVD or ECG abnormalities.

Reference Values for Cardiorespiratory Fitness in Healthy Koreans

We investigated reference values for cardiorespiratory fitness (CRF) for healthy Koreans and Koreans with coronary heart disease (CHD) and used them to identify inter-ethnic differences in CRF, differences over time in CRF, and differences in CRF between the healthy population and patients with CHD. The study population for healthy Koreans was derived from the database of KISS FitS (Korea Institute of Sports Science Fitness Standards) between 2014 and 2015. The study population for Koreans with CHD was derived from the database of the Korea University Guro Hospital Cardiac Rehabilitation Registry between June 2015 and December 2018. In healthy Koreans, there was a significant difference between sex and age groups for VO₂ max. The VO₂ max of healthy Koreans differed from that of Westerners in age-related reference values. Our results were not significantly different from those of the Korean population in the past, except for a small decline in the young population. There seemed to be a clear inter-ethnic difference in CRF. We could also identify signs of small change in CRF in younger age groups. Therefore, CRF should be assessed according to ethnic or national standards, and it will be necessary to establish a reference for each nation or ethnicity with periodic updates.

Workload-indexed blood pressure response is superior to peak systolic blood pressure in predicting all-cause mortality

AIMS

The association between peak systolic blood pressure (SBP) during exercise testing and outcome remains controversial, possibly due to the confounding effect of external workload (metabolic equivalents of task (METs)) on peak SBP as well as on survival. Indexing the increase in SBP to the increase in workload (SBP/MET-slope) could provide a more clinically relevant measure of the SBP response to exercise. We aimed to characterize the SBP/MET-slope in a large cohort referred for clinical exercise testing and to determine its relation to all-cause mortality.

METHODS AND RESULTS

Survival status for male Veterans who underwent a maximal treadmill exercise test between the years 1987 and 2007 were retrieved in 2018. We defined a subgroup of non-smoking 10-year survivors with fewer risk factors as a lower-risk reference group. Survival analyses for all-cause mortality were performed using Kaplan-Meier curves and Cox proportional hazard ratios (HRs (95% confidence interval)) adjusted for baseline age, test year, cardiovascular risk factors, medications and comorbidities. A total of 7542 subjects were followed over 18.4 (interquartile range 16.3) years. In lower-risk subjects (n = 709), the median (95th percentile) of the SBP/MET-slope was 4.9 (10.0) mmHg/MET. Lower peak SBP (<210 mmHg) and higher SBP/MET-slope (>10 mmHg/MET) were both associated with 20% higher mortality (adjusted HRs 1.20 (1.08-1.32) and 1.20 (1.10-1.31), respectively). In subjects with high fitness, a SBP/MET-slope > 6.2 mmHg/MET was associated with a 27% higher risk of mortality (adjusted HR 1.27 (1.12-1.45)).

CONCLUSION

In contrast to peak SBP, having a higher SBP/MET-slope was associated with increased risk of mortality. This simple, novel metric can be considered in clinical exercise testing reports.

Cardiorespiratory Fitness and Health Care Costs in Diabetes: The Veterans Exercise Testing Study

BACKGROUND

This study aimed to determine the association between cardiorespiratory fitness and healthcare expenditures among individuals with and without diabetes.

METHODS

Health care costs were quantified among 3924 consecutive men (mean age 58 ± 11 years) referred for a maximal exercise test, and compared according to presence (n = 2457) and absence (n = 1467) of diabetes and fitness. Fitness was classified into 4 categories based on age-stratified quartiles of peak metabolic equivalents: least-fit (5.1 ± 1.5 metabolic equivalents; n = 1044), moderately-fit (7.6 ± 1.5 metabolic equivalents; n = 938), fit (9.4 ± 1.5 metabolic equivalents; n = 988), and highly-fit (12.4 ± 2.2 metabolic equivalents; n = 954). Annual costs per subject were quantified over an 8-year period.

RESULTS

Age, BMI, and presence of cardiovascular disease (CVD) were similar between subjects with and without diabetes. After adjusting for age and presence of CVD, annual costs per person were higher among diabetics vs. non-diabetics. Individuals with and without diabetes in the highly-fit category had annual costs (US dollars x 10³) (mean ± standard deviation) that were on average $32,178 and $30,816 lower, respectively, than individuals in the least-fit category. For each 1-metabolic equivalent higher fitness, annual cost savings per person were $5,193 and $3,603 for individuals with and without diabetes, respectively.

CONCLUSIONS

Higher fitness is associated with lower health care costs. Cost savings associated with higher fitness are particularly evident among individuals with diabetes. The economic burden of diabetes may be reduced through interventions that target improvements in fitness.

Characteristics and Safety of Cardiopulmonary Exercise Testing in Elderly Patients with Cardiovascular Diseases in Korea

PURPOSE

Clinical use of cardiopulmonary exercise tests (CPETs) is increasing in elderly patients with cardiovascular (CV) diseases. However, data on Korean populations are limited. In this study, we aimed to examine the characteristics and safety of CPET in an elderly Korean population with CV disease.

MATERIALS AND METHODS

We retrospectively analyzed records of 1485 patients (older than 65 years in age, with various underlying CV diseases) who underwent CPET. All CPET was performed using the modified Bruce ramp protocol.

RESULTS

The mean age of patients was 71.6±4.7 years with 63.9% being men, 567 patients aged 60-65 years, 818 patients aged 70-79 years, and 100 patients aged 80-89 years. The mean respiratory exchange ratio was 1.09±0.14. During CPET, three adverse cardiovascular events occurred (total 0.20%), all ventricular tachycardia. All subjects showed an average exercise capacity of 21.3±5.5 mL/kg/min at peak VO₂ and 6.1±1.6 metabolic equivalents of task, and men showed better exercise capacity than women on most CEPT parameters. A significant difference was seen in peak oxygen uptake according to age group (65-69 years, 22.9±5.8; 70-79 years, 20.7±5.1; 80-89 years, 17.0±4.5 mL/kg/min, p<0.001). The most common causes for CPET termination were dyspnea (64.8%) and leg pain (24.3%), with higher incidence of leg pain in octogenarians compared to other age groups (65-69 years, 22.4%; 70-79 years, 24.6%; 80-89 years, 32.0%, p<0.001).

CONCLUSION

CPET was relatively a safe and useful modality to assess exercise capacity, even in an elderly Korean population with underlying CV diseases.

Characteristics and Outcomes in a Contemporary Group of Patients With Suspected Significant Mitral Stenosis Undergoing Treadmill Stress Echocardiography

Background:

In contemporary patients with suspected significant mitral stenosis (MS) undergoing rest and treadmill stress echocardiography, we assessed characteristics and factors associated with longer-term survival.

Methods:

We studied 515 consecutive patients (asymptomatic/atypical symptoms, mean left ventricular ejection fraction 58±2%; 43% male) with suspected at least moderate MS ([1] native mitral valve [MV]: resting mean MV gradient ≥5 mm Hg or area ≤1.5 cm 2 and [2] prosthetic valve: resting mean MV gradient ≥5 mm Hg or effective orifice area ≤2 cm) who underwent rest and treadmill stress echocardiography between 1/2003 and 12/2013. MS was categorized as rheumatic (n=170, 33%), postsurgical (prior mitral repair/replacement, n=245, 48%), and primary nonrheumatic (n=100, 19%). Primary outcome was all-cause mortality.

Results:

Mean resting MV gradient and right ventricular systolic pressure were 8.5±3 and 39±13 mm Hg. Patients achieved 95±29% age-sex predicted metabolic equivalents; peak-stress MV gradient and right ventricular systolic pressure were 17±7 and 61±14 mm Hg, respectively. At 54 days (median), 224 (44%) underwent invasive mitral procedure. At 6±4 years, 76 (15%) died. On survival analysis, primary nonrheumatic MS (hazard ratio [HR], 4.92), higher Society of Thoracic Surgeons score (HR, 1.92), lower % age-sex predicted metabolic equivalents (HR, 1.22), and higher peak-stress right ventricular systolic pressure (HR, 1.35), was associated with higher mortality, while invasive mitral procedures were associated with improved survival (HR, 0.67; all P <0.01).

Conclusions:

In asymptomatic patients (or with atypical symptoms) with significant MS undergoing treadmill stress echocardiography, higher mortality was associated with primary nonrheumatic MS, lower % age-sex predicted metabolic equivalents, and higher peak-stress right ventricular systolic pressure, while invasive MV procedures were associated with survival.

Cardiorespiratory Fitness and Coronary Artery Calcification in a Primary Prevention Population

Objective

To elucidate whether cardiorespiratory fitness (CRF) is protective or contributory to coronary artery disease plaque burden.

Patients and Methods

Study participants were working middle-aged men from the Mayo Clinic Executive Health Program who underwent coronary artery calcium (CAC) assessment and exercise treadmill testing for risk stratification. Data from January 1, 1995, through December 31, 2008, were considered. The CAC assessment score was used for lifelong plaque burden analysis; functional aerobic capacity (FAC) from treadmill testing was analyzed as 4 ranked categories of CRF. Known risk factors for cardiovascular disease, including family history, were also considered.

Results

In 2946 male patients in this retrospective, cross-sectional, observational study, known cardiovascular risk factor profiles and risk calculations tended to uniformly improve with increasing CRF, defined by the FAC level. Only the above-average group, or the third of 4 levels, was found consistently lower than other levels of FAC for CAC scores. The above-average group also had statistical significance after controlling for age, body mass index, and family history of coronary artery disease in a U-shaped distribution rather than the expected linear dose-response relationship. Plaque burden was significantly increased in patients with the highest FAC level (P=.005) compared with the above-average group despite the observed maximal risk factor optimization in all known conventional cardiovascular risk factors.

Conclusion

For men, maximal CRF is associated with increased atherosclerosis, established with CAC scores. By comparison, average-to-moderate CRF appears to be cardioprotective regardless of either age or the influence of other contributing, recognized cardiac risk factors.