Moderate Endurance Exercise Increases Arrhythmia Susceptibility and Modulates Cardiac Structure and Function in a Sexually Dimorphic Manner

BACKGROUND

Although moderate endurance exercise has been reported to improve cardiovascular health, its effects on cardiac structure and function are not fully characterized, especially with respect to sexual dimorphism. We aimed to assess the effects of moderate endurance exercise on cardiac physiology in male versus female mice.

METHODS AND RESULTS

C57BL/6J mice of both sexes were run on a treadmill for 6 weeks. ECG and echocardiography were performed every 2 weeks. After 6 weeks of exercise, mice were euthanized, and triple parametric optical mapping was performed on Langendorff perfused hearts to assess cardiac electrophysiology. Arrhythmia inducibility was tested by programmed electrical stimulation. Left ventricular tissue was fixed, and RNA sequencing was performed to determine exercise-induced transcriptional changes. Exercise-induced left ventricular dilatation was observed in female mice alone, as evidenced by increased left ventricular diameter and reduced left ventricular wall thickness. Increased cardiac output was also observed in female exercised mice but not males. Optical mapping revealed further sexual dimorphism in exercise-induced modulation of cardiac electrophysiology. In female mice, exercise prolonged action potential duration and reduced voltage-calcium influx delay. In male mice, exercise reduced the calcium decay constant, suggesting faster calcium reuptake. Exercise increased arrhythmia inducibility in both male and female mice; however, arrhythmia duration was increased only in females. Lastly, exercise-induced transcriptional changes were sex dependent: females and males exhibited the most significant changes in contractile versus metabolism-related genes, respectively.

CONCLUSIONS

Our data suggest that moderate endurance exercise can significantly alter multiple aspects of cardiac physiology in a sex-dependent manner. Although some of these effects are beneficial, like improved cardiac mechanical function, others are potentially proarrhythmic.

Cardiovascular and Pulmonary Responses to Acute Use of Electronic Nicotine Delivery Systems and Combustible Cigarettes in Long-Term Users

BACKGROUND

The acute cardiovascular and pulmonary effects of contemporary electronic nicotine delivery systems (ENDS) in long-term users are not known.

RESEARCH QUESTION

What are the cardiovascular and pulmonary responses to an acute 15-min product use challenge with ENDS and combustible cigarettes in regular nicotine-containing product users compared with control participants who do not use tobacco or vape?

STUDY DESIGN AND METHODS

Observational challenge study before and after nicotine-containing product use of 395 individuals who used ENDS exclusively (n = 164; exhaled carbon monoxide level, < 5 parts per million [ppm]; positive urine NicCheck I [Mossman Associates] results, 82%; fourth-generation ENDS), participants who smoked cigarettes exclusively (n = 117; carbon monoxide level, > 5 ppm; positive urine NicCheck I results), and control participants (n = 114; carbon monoxide level, < 5 ppm; negative urine NicCheck I results).

RESULTS

During the 15-min product challenge, cigarette users took a median of 14.0 puffs (interquartile range [IQR], 9.3 puffs); ENDS users took 9.0 puffs (IQR, 7.5 puffs; P < .001). After product challenge, compared with control participants, ENDS users showed greater increases in adjusted mean differences in systolic BP (5.6 mm Hg [95% CI, 4.4-6.8 mm Hg] vs 2.3 mm Hg [95% CI, 0.8-3.8 mm Hg]; P = .001), diastolic BP (4.2 mm Hg [95% CI, 3.3-5.0 mm Hg] vs 2.0 mm Hg [95% CI, 1.1-3.0 mm Hg; P = .003), and heart rate (4.8 beats/min [95% CI, 4.0-5.6 beats/min] vs -1.3 beats/min [95% CI, -2.2 to -0.3 beats/min]; P < .001) and greater reductions in brachial artery diameter (-0.011 cm [95% CI, -0.013 to 0.009 cm] vs -0.006 cm [95% CI, -0.004 to -0.009 cm]; P = .003), time-domain heart rate variability (-7.2 ms [95% CI, -10.5 to -3.7 ms] vs 3.6 ms [95% CI, 1.6-9.3 ms]; P = .001), and FEV1 (ENDS: -4.1 [95% CI, -5.4 to -2.8] vs control participants: -1.1 [95% CI, -2.7 to 0.6]; P = .005) with values similar to those of cigarette users. ENDS users performed worse than control participants on all exercise parameters, notably metabolic equivalents (METs; adjusted mean difference, 1.28 METs [95% CI, 0.73-1.83 METs]; P < .001) and 60-s heart rate recovery (adjusted mean difference, 2.9 beats/min [95% CI, 0.7-5.0 beats/min]; P = .008).

INTERPRETATION

ENDS users had acute worsening of blood pressure, heart rate, and heart rate variability, as well as vasoconstriction, impaired exercise tolerance, and increased airflow obstruction after vaping, compared to control participants.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT03863509; URL: www.

CLINICALTRIALS

gov.

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.

Incremental Value of Exercise ECG to Myocardial Perfusion Single-Photon Emission Computed Tomography for Prediction of Cardiac Events

Background Both myocardial perfusion single-photon emission computed tomography (MPS) and exercise ECG (Ex-ECG) carry prognostic information in patients with stable chest pain. However, it is not fully understood if combining the findings of MPS and Ex-ECG improves risk prediction. Current guidelines no longer recommend Ex-ECG for diagnostic evaluation of chronic coronary syndrome, but Ex-ECG could still be of incremental prognostic importance. Methods and Results This study comprised 908 consecutive patients (age 63.3±9.4 years, 49% male) who performed MPS with Ex-ECG. Subjects were followed for 5 years. The end point was a composite of cardiovascular death, acute myocardial infarction, unstable angina, and unplanned percutaneous coronary intervention. National registry data and medical charts were used for end point allocation. Combining the findings of MPS and Ex-ECG resulted in concordant evidence of ischemia in 72 patients or absence of ischemia in 634 patients. Discordant results were found in 202 patients (MPS-/Ex-ECG+, n=126 and MPS+/Ex-ECG-, n=76). During follow-up, 95 events occurred. Annualized event rates significantly increased across groups (MPS-/Ex-ECG- =1.3%, MPS-/Ex-ECG+ =3.0%, MPS+/Ex-ECG- =5.1% and MPS+/Ex-ECG+ =8.0%). In multivariable analyses MPS was the strongest predictor regardless of Ex-ECG findings (MPS+/Ex-ECG-, hazard ratio [HR], 3.0, P=0.001 or MPS+/Ex-ECG+, HR,4.0, P<0.001). However, an abnormal Ex-ECG almost doubled the risk in subjects with normal MPS (MPS-/Ex-ECG+, HR, 1.9, P=0.04). Conclusions In patients with chronic coronary syndrome, combining the results from MPS and Ex-ECG led to improved risk prediction. Even though MPS is the stronger predictor, there is an incremental value of adding data from Ex-ECG to MPS, especially in patients with normal MPS.

Feasibility of Remote Delivering an Exercise and Lifestyle Education Program for Individuals Living with Prediabetes and Diabetes in Brazil

This study aimed to test the feasibility of remote delivering a 12-week exercise and lifestyle education program (ExLE) or a 12-week exercise program (Ex) for individuals with prediabetes and diabetes in terms of acceptability, implementation, practicality, and limited efficacy. The programs were internet- or telephone-based delivered, depending on the participants' internet access and technology literacy. Of the 196 individuals screened, 15 were included in the study (internet-based delivery (n = 13); telephone-based delivery (n = 2)). Twelve participants completed the program they were randomized to, and most reported being satisfied with the study interventions (acceptability). Data collection procedures, weekly follow-up, study website visits, and educational materials were proper (implementation), and the adherence rate to study interventions ranged from 24% to 58% (practicality). Additionally, both programs (ExLE and Ex) seemed to promote beneficial changes in functional capacity (limited efficacy). The internet-based remote delivery of the interventions showed feasibility. Therefore, in future trials, exercise and educational interventions can be internet-based remote delivered to individuals with prediabetes and diabetes with internet access and technology literacy. In addition, some adjustments to eligibility criteria, study websites, more accessible ways of recording exercise sessions and using educational materials, and an initial supervised exercise session are recommended.

Patient-Reported Symptoms and Subsequent Risk of Myocardial Infarction in Chronic Kidney Disease

BACKGROUND AND OBJECTIVES

Although patient-reported symptoms often precede acute presentations of cardiovascular disease, patients with nondialysis-requiring CKD are less likely to have typical symptoms of atherosclerotic disease when presenting with acute myocardial infarction. However, the associations between typical atherosclerotic symptoms and subsequent risk of myocardial infarction are unknown in ambulatory patients with CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

To determine whether typical atherosclerotic symptoms are associated with risk for subsequent myocardial infarction in people with CKD, we examined participants from the Chronic Renal Insufficiency Cohort Study. Chest pain, shortness of breath, and inability to climb stairs were evaluated annually using the Kidney Disease Quality of Life Instrument. Associations between categorical time-updated symptoms and physician-adjudicated incident myocardial infarction were assessed using Cox regression models.

RESULTS

Among 3910 participants (mean age of 58±11 years; mean eGFR =44±15 ml/min per 1.73 m2), there were 476 incident myocardial infarctions over a median follow-up period of 10.4 years (interquartile range, 5.36-12.6 years). Median time from symptom assessment to incident myocardial infarction was 213 days (interquartile range, 111-333 days). Compared with no symptoms, mild, and moderate or worse, symptoms of chest pain (hazard ratio, 1.30; 95% confidence interval, 1.01 to 1.67; and hazard ratio, 1.70; 95% confidence interval, 1.27 to 2.27, respectively) and shortness of breath (hazard ratio, 1.37; 95% confidence interval, 1.10 to 1.70; and hazard ratio, 1.33; 95% confidence interval, 1.05 to 1.69, respectively) were significantly associated with greater risks for subsequent myocardial infarction. Participants reporting mild and severe limitations in climbing stairs (versus no limitation) had significantly higher adjusted risk of myocardial infarction (hazard ratio, 1.44; 95% confidence interval, 1.10 to 1.89; and hazard ratio, 1.89; 95% confidence interval, 1.44 to 2.49, respectively).

CONCLUSIONS

In a large ambulatory cohort of adults with CKD, symptoms of atherosclerotic cardiovascular disease were strongly associated with a higher risk for subsequent myocardial infarction.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2022_03_17_CJN12080921.mp3.

Implementation of supervised exercise therapy in a veteran population with symptomatic claudication

Background:

Real-world implementation of supervised exercise therapy (SET) referral for symptomatic intermittent claudication has been limited by poor provider awareness around reimbursement and low patient adherence owing to factors including limited center availability and long travel distances to sites.

Methods:

In this study, 76 of 77 consecutive male veteran patients with intermittent claudication managed at a single-center vascular specialty clinic were referred to SET prior to revascularization. Pre- and post-SET submaximal exercise treadmill testing was performed for assessment of exercise capacity in metabolic equivalents (METs).

Results:

In the 48.7% of subjects who completed 36 sessions of SET ( n = 37), the average improvement in METs was 60.3%, reflecting improvement from baseline average of 3.4 METs to 5.5 METs after SET. Another 14 patients pursued self-guided exercise therapy and 25 patients declined any participation in exercise therapy. Reasons for declining participation in SET included inadequate transportation, cost of copayment, and interference with full-time work schedules. There was a nonsignificant numeric trend toward improved change in ankle–brachial index in the combined SET and self-guided exercise groups compared to those that declined exercise therapy (0.011 ± 0.124 vs –0.040 ± 0.105, p = 0.156).

Conclusion:

High acceptance of referral to SET is possible, despite the limitations to implementation. Incorporation of novel pre- and post-SET submaximal exercise treadmill testing allows for assessment of change in exercise capacity and aids in risk stratification and management of intermittent claudication symptoms.

Determinants of Exercise Capacity Following ST-Elevation Myocardial Infarction (STEMI)

BACKGROUND

Abnormal left ventricular systolic and diastolic function and reduced exercise capacity are associated with worse prognosis following ST-elevation myocardial infarction (STEMI). However, evidence is lacking on the determinants of exercise capacity following STEMI. We sought to determine the impact of systolic and diastolic dysfunction on exercise capacity and outcomes following first-ever STEMI.

METHODS

In a retrospective analysis of 139 consecutive STEMI patients who had a transthoracic echocardiogram following STEMI and completed exercise treadmill testing, the primary outcome was to identify clinical and echocardiographic determinants of exercise capacity, and the secondary outcome was to identify determinants of major adverse cardiac events (MACEs).

RESULTS

Mean number of metabolic equivalents (METs > 8) was used as a cut-off. Age, female sex, anterior infarction, abnormal diastolic function, minimum left atrial indexed volume (LAVI_min) ≥ 18 mL/m², average e', and E/e' were associated with METs ≤ 8, but not left ventricular ejection fraction (LVEF). On multivariate analysis, LAVI_min (OR 4.3, 95%CI 1.3-14.2; p = 0.017), anterior infarction (OR 2.6, 95%CI 1.2-5.9; p = 0.022), and abnormal diastolic function (OR 3.73, 95%CI 1.7-8.4; p = 0.001) were independent predictors of METs ≤ 8. On Kaplan-Meier analysis, METs ≤ 8 (p = 0.01) and abnormal diastolic function (p = 0.04) were associated with MACEs (median follow-up 2.3 years). METs ≤ 8 was an independent predictor of MACEs (HR 3.4, 95%CI 1.2-9.8; p = 0.02).

CONCLUSIONS

Following first-ever STEMI, increased LAVI_min, anterior infarction, and abnormal diastolic function were independent predictors of reduced exercise capacity. Furthermore, reduced exercise capacity was an independent predictor of MACEs. These results highlight important prognostic and therapeutic implications related to abnormal diastolic function in STEMI patients that are distinct from those with LV systolic impairment.

The additional prognostic value of myocardial perfusion SPECT in patients with known coronary artery disease with high exercise capacity

BACKGROUND

The prognostic value of myocardial perfusion imaging (MPI) in patients with known coronary artery disease (CAD) and high exercise capacity is still unknown. We sought to determine the MPI additional prognostic value over electrocardiography (ECG) stress testing alone in patients with known CAD who achieved ≥ 10 metabolic equivalents (METs).

METHODS AND RESULTS

We evaluated 926 patients with known CAD referred for MPI with exercise stress. Patients were followed for a mean of 32.4 ± 9.7 months for the occurrence of all-cause death or nonfatal myocardial infarction (MI). Those achieving ≥ 10 METs were younger, predominantly male, and had lower prevalence of cardiovascular risk factors. Patients reaching ≥ 10 METs had a lower annualized rate of hard events compared to their counterparts achieving < 10 METs (1.13%/year vs 3.95%/year, P < .001). Patients who achieved ≥ 10 METs with abnormal scans had a higher rate of hard events compared to those with normal scans (3.37%/year vs 0.57%/year, P = .023). Cardiac workload < 10 METs and an abnormal MPI scan were independent predictors of hard events.

CONCLUSIONS

MPI is able to stratify patients with known CAD achieving ≥ 10 METs for the occurrence of all-cause death and nonfatal MI, with incremental prognostic value over ECG stress test alone.

The Six-Minute Step Test as a Predictor of Functional Capacity according to Peak VO2 in Cardiac Patients

BACKGROUND

Six-minute step test (6MST) is a simple way to evaluate functional capacity, although it has not been well studied in patients with coronary artery disease (CAD) or heart failure (HF).

OBJECTIVE

Analyze the association between the 6MST and peak oxygen uptake (VO2peak) and develop an equation for estimating VO2peak based on the 6MST, as well as to determine a cutoff point for the 6MST that predicts a VO2peak ≥20 mL.Kg-1.min-1.

METHODS

In 171 patients who underwent the 6MST and a cardiopulmonary exercise test, correlation, regression, and ROC analysis were used and a p < 0.05 was admitted as significant.

RESULTS

mean age was 60±14 years and 74% were male. Mean left ventricle ejection fraction was 57±16%, 74% had CAD and 28% had HF. Mean VO2peak was 19±6 mL.Kg-1.min-1 and mean 6MST performance was 87±45 steps. Association between 6MST and VO2peak was r 0.69 (p <0.001). The model VO2peak =19.6 + (0.075 x 6MST) - (0.10 x age) for men and VO2peak =19.6 + (0.075 x 6MST) - (0.10 x age) - 2 for women could predict VO2peak based on 6MST results (adjusted R 0.72; adjusted R2 0.53). The most accurate cutoff point for 6MST to predict a VO2peak ≥20 mL.Kg-1.min-1 was >105 steps (AUC 0.85; 95% CI 0.79 -0.90; p <0.001).

CONCLUSION

An equation for predicting VO2peak based on 6MST results was derived, and a significant association was found between 6MST and VO2peak. The cutoff point for 6MST, which predicts a VO2peak ≥20 mL.Kg-1.min-1, was >105 steps. (Arq Bras Cardiol. 2021; 116(5):889-895).

A high exercise workload of ≥ 10 METS predicts a low risk of significant ischemia and cardiac events in older adults

BACKGROUND

Patients who achieve ≥ 10 METS during exercise SPECT myocardial perfusion imaging (MPI) have very low rates of significant ischemia and major adverse cardiac events (MACE). It is unknown how many older adults can achieve ≥ 10 METS, and if low risk extends to this subgroup.

METHODS AND RESULTS

We examined the workload achieved, prevalence and predictors of ischemia, and MACE (cardiac death, non-fatal MI, late revascularization) in a cohort of 382 patients ≥ 65 years of age who underwent exercise 99mTc SPECT MPI. The cohort was 64.4% male and 36.9% had known coronary artery disease (CAD). All achieved ≥ 85% of maximum age-predicted heart rate. A workload of ≥ 10 METS was achieved in 25.4%; 50.3% attained 7-9 METS, and 24.4% reached < 7 METS. There was a stepwise decrease in prevalence of any ischemia and significant ischemia (≥ 10% of the left ventricle (LV)) as workload increased (P = 0.037). Patients achieving ≥ 10 METS had a 3.1% prevalence of ≥ 10% LV ischemia (1.2% in those without ST depression). Cardiac death and MACE rates in the ≥ 10 METS subgroup were 0.6%/year and 2.6%/year over a median 7.0 years of follow-up.

CONCLUSIONS

A substantial proportion of older adults who undergo exercise SPECT MPI can achieve ≥ 10 METS. This subgroup has low rates of significant LV ischemia and MACE. The favorable diagnostic and prognostic implications of achieving a high workload in an older adult population suggest it is feasible, with certain exceptions, to include this subgroup in workload-based strategies of provisional imaging.

Usefulness of Excellent Functional Capacity in Men and Women With Ischemic Exercise Electrocardiography to Predict a Negative Stress Imaging Test and Very Low Late Mortality

Exercise electrocardiography (ExECG) is widely employed to assess patients for coronary artery disease but it has limited diagnostic accuracy. Many patients with positive (ischemic) tests based on exercise-induced ST depression undergo secondary evaluation by noninvasive stress imaging. We hypothesized that high functional capacity in patients with positive ExECG could predict: (1) negative results in secondary evaluation by exercise echocardiography (ESE) or myocardial perfusion scintigraphy (MPS) and (2) low mortality on late follow-up. We evaluated 511 consecutive patients (312 men, 199 women; age 51 ± 9 years) referred for ESE or MPS after an ischemic ExECG at a treadmill workload of ≥10 metabolic equivalents. All-cause mortality was also obtained. Of 511 patients, 401 underwent ESE and 110 had MPS for secondary study. ESE was negative in 94% (376 of 401) and positive in 6% (25 of 401). MPS was also negative in 94% (103 of 110) and positive in 6% (7 of 110). Total stress imaging results were negative in 92% (286 of 312) of men and 97% (193 of 199) of women. During follow-up of approximately 6 years, there were 3 deaths with total all-cause mortality of 0.6% and average annual mortality of 0.1%. In conclusion, high functional capacity in patients with an ischemic ExECG predicts a negative ESE or MPS in a large majority of patients and very favorable late survival in both men and women. These results suggest that patients with ischemic ExECGs and a workload of ≥10 metabolic equivalents during ExECG may not require additional noninvasive or invasive evaluation.

Clinical outcomes of discordant exercise electrocardiographic and echocardiographic findings compared with concordant findings in patients with chest pain and no history of coronary artery disease: An observational study

The aim of this study was to evaluate comparative clinical outcomes of discordant electrocardiographic (ECG) and echocardiographic (Echo) findings compared with concordant findings during treadmill exercise echocardiography in patients with chest pain and no history of coronary artery disease (CAD).A total of 1725 consecutive patients who underwent treadmill echocardiography with chest pain and no history of CAD were screened. The patients were classified into 4 groups: ECG-/Echo- (negative ECG and Echo), ECG+/Echo- (positive ECG and negative Echo), ECG-/Echo+, and ECG+/Echo+. Concomitant CAD was determined using coronary angiography or coronary computed tomography. Major adverse cardiac events (MACEs) were defined as a composite of coronary revascularization, acute myocardial infarction, and death.MACEs were similar between ECG-/Echo- and ECG+/Echo- groups. Compared with ECG+/Echo- group, ECG-/Echo+ group had more MACEs (adjusted hazard ratio [HR] adjusted by clinical risk factors [95% confidence interval {CI}], 3.57 [1.75-7.29], P < .001). Compared with ECG+/Echo+ group, ECG-/Echo+ group had lower prevalence of concomitant CAD and fewer MACEs (HR, 0.49 [0.29-0.81], P = .006).Positive exercise Echo alone during treadmill exercise echocardiography had worse clinical outcomes than positive ECG alone, and the latter had similar outcomes to both negative ECG and Echo. Positive exercise Echo alone also had better clinical outcomes than both positive ECG and Echo. Therefore, exercise Echo findings might be superior for predicting clinical outcomes compared with exercise ECG findings. Additional consideration of ECG findings on positive exercise Echo will also facilitate better prediction of clinical outcomes.

Incremental Prognostic Value of Exercise Stress Testing in Primary Prevention

In primary prevention, addition of C-reactive protein and family history to standard risk factor assessment (Reynolds Risk Score or RRS) provides superior risk stratification for future cardiovascular (CV) events. We sought to assess whether addition of functional capacity to RRS provided incremental prognostic value. This was a prospective observational cohort study of 3,964 consecutive asymptomatic adults without documented CV disease (mean age 51 years, 78% men) evaluated between 2005 and 2013, who underwent clinical and treadmill stress testing at baseline. RRS was calculated; % age-gender predicted metabolic equivalents (AGP-METs) achieved and heart rate recovery (HRR) were recorded. End point was death and myocardial infarction. Findings were tested in derivation (n = 1,982) and validation samples (n = 1,982). Mean RRS and C-reactive protein were 3.7 ± 4 and 2 ± 4 mg/dl. Nine percent had family history of premature CV disease. %AGP-METs achieved, and HRR were 113 ± 20 and 24 ± 8 beats/min. Forty-six percent achieved <110% AGP-METs, whereas 41% had RRS ≥3. At 7.3 ± 3 years, there were 83 (2%) events (39 in derivation and 44 in validation samples). In derivation group, on multivariable survival analysis, higher RRS (Hazard ratio or HR 1.27 [1.07 to 1.39]), lower % AGP METs (HR 1.21 [1.09 to 1.34]) achieved and abnormal (<12 beats/min) HRR (HR 1.15 [1.02 to 1.23]) were associated with increased longer-term events (all p <0.01). Findings were similar in validation group. Cutoffs of RRS >3 and %AGP-METs <110 were associated with increased longer-term events on spline analysis in the derivation group. The continuous net reclassification improvement for longer-term events, when %AGP-METs was added to RRS was 0.79 (95% confidence interval 0.52 to 1.05; p <0.01). Findings were confirmed in validation group. In conclusion, in primary prevention, addition of exercise capacity to RRS (incorporating traditional risk factors, family history, and inflammation) provides incremental prognostic value.

Non Electrocardiographic alterations in exercise testing in asymptomatic women. Associations with cardiovascular risk factors

OBJECTIVES

To estimate the prevalence of exercise testing alterations in middle-aged women without symptoms of heart disease and to verify the associations of functional capacity and heart rate behavior during and after exercise with cardiovascular risk factors.

METHODS

A cross-sectional study was conducted with 509 asymptomatic women aged between 46 and 65 years who underwent clinical evaluations and exercise testing (Bruce protocol). The heart rate behavior was evaluated by the maximal predicted heart rate achieved, chronotropic index and recovery heart rate.

RESULTS

The mean age was 56.4±4.8 years, and 13.4% of the patients had a Framingham risk score above 10%. In the exercise treadmill testing, 58.0% presented one or more of the following alterations (listed in order of ascending prevalence): symptoms (angina, dyspnea, and dizziness), ST-segment depression, arrhythmia, reduction in recovery heart rate of ≤12 bpm at 1 minute, altered maximal predicted heart rate achieved, abnormal blood pressure, functional capacity deficiency, and altered chronotropic index. In the multivariate analysis, the following associations (odds ratio) were observed for these alterations: chronotropic index was associated with obesity (2.08) and smoking (4.47); maximal predicted heart rate achieved was associated with smoking (6.45); reduction in the recovery heart rate at 1 minute was associated with age (1.09) and obesity (2.78); functional capacity was associated with age (0.92), an overweight status (2.29) and obesity (6.51).

CONCLUSIONS

More than half of middle-aged women without cardiovascular symptoms present alterations in one or more exercise testing parameters. Alterations in the functional capacity or heart rate behavior, as verified by exercise testing, are associated with age, smoking, an overweight status and obesity.

Exercise Capacity, Heart Failure Risk, and Mortality in Older Adults: The Health ABC Study

INTRODUCTION

Data on the association between exercise capacity and risk for heart failure (HF) in older adults are limited.

METHODS

This study examined the association of exercise capacity, and its change over time, with 10-year mortality and incident HF in 2,935 participants of the Health, Aging, and Body Composition Study without HF at baseline (age, 73.6 [SD=2.9] years; 52.1% women; 41.4% black; 58.6% white). This cohort was initiated in 1997-1998 and exercise capacity was evaluated with a long-distance corridor walk test (LDCW) at baseline and Year 4. Outcomes were collected in 2007-2008 and initial analysis performed in 2014.

RESULTS

Ten-year incident HF for completers (n=2,245); non-completers (n=331); and those excluded from LDCW for safety reasons (n=359) was 11.4%, 19.2%, and 23.0%, respectively. The corresponding 10-year mortality was 27.9%, 41.1%, and 42.4%. In models accounting for competing mortality, the adjusted subhazard ratio for HF was 1.37 (95% CI=1.00, 1.88; p=0.049) in non-completers and 1.41 (95% CI=1.06, 1.89; p=0.020) in those excluded versus completers. Non-completers (adjusted hazard ratio, 1.49; 95% CI=1.21, 1.84; p<0.001) and those excluded (hazard ratio, 1.27; 95% CI=1.04, 1.55; p=0.016) had elevated mortality. In adjusted models, LDCW performance variables were associated mainly with mortality. Only 20-meter walking speed and resting heart rate retained prognostic value for HF. Longitudinal changes in LDCW did not predict subsequent incident HF or mortality.

CONCLUSIONS

Completing an LDCW is strongly associated with lower 10-year mortality and HF risk in older adults. Therefore, walking capacity may serve as an early risk marker.

Exercise capacity and mortality - a follow-up study of 3033 subjects referred to clinical exercise testing

BACKGROUND

Exercise stress testing is used as a diagnostic and prognostic tool. We determined the prognostic significance of exercise test findings for cardiovascular (CVD) and all-cause mortality in men and women.

MATERIAL AND METHODS

3033 subjects underwent a symptom-limited bicycle exercise test. Exercise capacity was defined as the mean of last four minutes of exercise workload.

RESULTS

During an average follow-up of 19 years, 186 (11.6%) CVD and 370 (20.6%) all-cause deaths in men and 57 (5.0%) CVD and 155 (12.5%) all-cause deaths in women occurred. Among exercise test variables (workload, ECG, BP, HR), exercise capacity was the strongest predictor of mortality. Low exercise capacity (1st quartile) was associated with a hazard ratio of 4.2 (95% CI: 1.7, 10.8) for CVD and 4.0 (95% CI: 2.5, 6.4) for all-cause mortality compared with high exercise capacity (4th quartile) among men and in women with a 5.4-fold (95% CI: 1.2, 24.0) risk for CVD and 2.3-fold (95% CI: 1.2, 4.3) risk for all-cause mortality, respectively. The relationship between other exercise test variables and mortality was much weaker.

CONCLUSIONS

Among exercise test variables exercise capacity was the strongest predictor of CVD and all-cause mortality in both genders, and especially CVD deaths in women. Key Messages Exercise capacity was the most powerful predictor of CVD and all-cause mortality in both men and women. Low exercise capacity is a strong predictor of CVD death, especially among women.

Validation of a cardiorespiratory fitness assessment for firefighters

Currently, a submaximal protocol is used to measure cardiorespiratory fitness in firefighters by estimating their true aerobic capacity (V[Combining Dot Above]O2max); however, this submaximal test has not been cross-validated among firefighters. Thirty firefighters (85% male, 15% female), completed the submaximal protocol and the maximal (Bruce) treadmill protocol on separate occasions. Pearson's correlation analyses between the submaximal and Bruce protocol revealed a significant moderate positive correlation (r = 0.635, p = 0.005). The range of mean V[Combining Dot Above]O2max values and SDs produced from the submaximal and maximal protocols varied greatly (35.4-50.9 vs. 28.6-58.4 ml·kg·min, and SD of 3.91 vs. 7.22, respectively). The submaximal V[Combining Dot Above]O2 test underestimated the true V[Combining Dot Above]O2max in the majority of firefighters (72.4%) and overestimated the true V[Combining Dot Above]O2max in the remainder of firefighters. Participants with a higher body fat percentage were more likely (p = 0.0157) to have an overestimated true V[Combining Dot Above]O2max than those with a lower-body fat percentage. Our results indicate the current submaximal V[Combining Dot Above]O2 test used to measure cardiorespiratory fitness in firefighters is an improvement over previous protocols. However, our findings also show that the accuracy of this submaximal test for predicting the true V[Combining Dot Above]O2max in firefighters is questionable, and may not identify firefighters who possess substandard cardiorespiratory fitness, particularly in those with a higher percentage of body fat. Thus, the results of this study indicate that improvements to the current Fire Service Joint Management, Wellness & Fitness Initiative (WFI) V[Combining Dot Above]O2 assessment is still needed to accurately reflect the true V[Combining Dot Above]O2max of individual firefighters.

Exercise capacity as an independent risk factor for adverse cardiovascular outcomes among nondiabetic and diabetic patients

INTRODUCTION

To investigate if decreased exercise capacity is an independent risk factor for major adverse cardiovascular events (MACE) in diabetics and nondiabetics.

MATERIAL AND METHODS

The association of decreased exercise capacity (EC) during a treadmill exercise sestamibi stress test with MACE was investigated in 490 nondiabetics and 404 diabetics. Mean follow-up was 53 months.

RESULTS

Nondiabetics with a predicted EC < 85% had a higher prevalence of myocardial ischemia (34% vs. 19%, p = 0.0002), 2- or 3-vessel obstructive coronary artery disease (CAD) (31% vs. 13%, p = 0.016), myocardial infarction (MI) (17% vs. 7%, p = 0.0005), stroke (8% vs. 2%, p = 0.002), death (11% vs. 3%, p = 0.0002), and MI or stroke or death at follow-up (32% vs. 11%, p < 0.001) compared to nondiabetics with a predicted EC ≥ 85%. Diabetics with a predicted EC < 85% had a higher prevalence of myocardial ischemia (48% vs. 32%, p = 0.0009), 2- or 3-vessel obstructive CAD (54% vs. 28%, p = 0.001), MI (32% vs. 14%, p < 0.001), stroke (22% vs. 6%, p < 0.001), death (17% vs. 9%, p = 0.031), and MI or stroke or death at follow-up (65% vs. 27%, p < 0.001). Stepwise Cox regression analysis showed decreased EC was an independent and significant risk factor for MACE among nondiabetics (hazard ratio 3.3, p < 0.0001) and diabetics (hazard ratio 2.7, p < 0.0001).

CONCLUSIONS

Diabetics and nondiabetics with decreased EC were at increased risk for MACE with nondiabetics and decreased EC at similar risk as diabetics with normal EC.

Relation between self-reported physical activity level, fitness, and cardiometabolic risk

Physical activity and cardiorespiratory fitness are associated with improved cardiovascular health and reduced all-cause mortality. The relation between self-reported physical activity, objective physical fitness, and the association of each with cardiometabolic risk has not been fully described. We studied 2,800 healthy Brazilian subjects referred for an employer-sponsored health screening. Physical activity level was determined as "low," "moderate," or "high" with the International Physical Activity Questionnaire: Short Form (IPAQ-SF). Fitness was measured as METs achieved on a maximal, symptom-limited, treadmill stress test. Using multivariate linear regression analysis, we calculated age, gender, and smoking-adjusted correlation coefficients among IPAQ-SF, fitness, and cardiometabolic risk factors. Mean age of study participants was 43 ± 9 years; 81% were men, and 43% were highly active. Mean METs achieved was 12 ± 2. IPAQ-SF category and fitness were moderately correlated (r = 0.377). Compared with IPAQ-SF category, fitness was better correlated with cardiometabolic risk factors including anthropomorphic measurements, blood pressure, fasting blood glucose, dyslipidemia, high-sensitivity C-reactive protein, and hepatic steatosis (all p <0.01). Among these, anthropomorphic measurements, blood pressure, high-sensitivity C-reactive protein, and hepatic steatosis had the largest discrepancies in correlation, whereas lipid factors had the least discrepant correlation. When IPAQ-SF and fitness were discordant, poor fitness drove associations with elevated cardiometabolic risk. In conclusion, self-reported physical activity level and directly measured fitness are moderately correlated, and the latter is more strongly associated with a protective cardiovascular risk profile.

[Prevention by physical activity. The relevance of physical fitness]

Regular physical activity is now recognized as an important and very effective step to prevent many diseases, especially those of the cardiovascular system. Many studies within the last 20 years have also shown that exercise capacity or fitness is an important prognostic factor in healthy subjects and patients with cardiovascular diseases for both mortality and morbidity. Physical fitness, which is mainly determined by regular physical activity or training, can be analyzed by maximal exercise testing using the treadmill or cycle ergometry. In addition, fitness is also based on genetic factors. There are some methodological criticisms concerning self-reported questionnaires of physical activity, MET (metabolic equivalent) calculations and exhaustion during maximal voluntary stress testing. However, the results of both approaches are valid and reliable for daily use. Accordingly, every physician regardless of his or her discipline should encourage all patients at every visit to follow a healthy lifestyle, including regular exercise and physical activity. This also applies to older patients, who especially benefit from exercise and physical activity.

Evidence-based risk assessment and recommendations for physical activity clearance: established cardiovascular disease1This paper is one of a selection of papers published in this Special Issue, entitled Evidence-based risk assessment and recommendations for physical activity clearance, and has undergone the Journal’s usual peer review process

Physical activity is an effective lifestyle therapy for patients at risk for, or with, documented cardiovascular disease (CVD). Current screening tools — the Physical Activity Readiness Questionnaire (PAR-Q) and the Physical Activity Readiness Medical Evaluation (PARmed-X) — require updating to align with risk/benefit evidence. We provide evidence-based recommendations to identify individuals with CVD at lower risk, intermediate risk, or higher risk of adverse events when participating in physical activity. Forms of exercise and the settings that will appropriately manage the risks are identified. A computer-assisted search of electronic databases, using search terms for CVD and physical activity risks and benefits, was employed. The Appraisal of Guidelines for Research and Evaluation were applied to assess the evidence and assign a strength of evidence rating. A strength rating for the physical activity participation clearance recommendation was assigned on the basis of the evidence. Recommendations for physical activity clearance were made for specific CVD groups. Evidence indicates that those who are medically stable, who are involved with physical activity, and who have adequate physical ability can participate in physical activity of lower to moderate risk. Patients at higher risk can exercise in medically supervised programs. Systematic evaluation of evidence indicates that clinically stable individuals with CVD may participate in physical activity with little risk of adverse events. Therefore, changes in the PAR-Q should be undertaken and a process of assessment and consultation to replace the PARmed-X should be developed. Patients at lower risk may exercise at low to moderate intensities with minimal supervision. Those at intermediate risk should exercise with guidance from a qualified exercise professional. Patients at higher risk should exercise in medically supervised programs.

Using an abnormal increase in postexercise systolic blood pressure to diagnose coronary artery disease in gerontal patients

Data from 66 patients ≥ 60 years old with suspected coronary artery disease (CAD) were studied to determine the diagnostic value of an abnormal increase in postexercise systolic blood pressure (SBP) for detecting CAD in gerontal patients. Treadmill exercise testing (TET) and selective coronary angiography (CAG) were carried out and SBP was measured pre-TET and at each minute during a 6-min post-TET recovery phase. Abnormal increase in postexercise SBP was defined as a higher SBP compared with that measured earlier during the 6-min post-TET period. An abnormal increase of ≥ 7 mmHg in postexercise SBP had a statistically significantly better specificity, and also showed higher sensitivity and accuracy, than ST-segment depression ≥ 1 mV in identifying gerontal patients with CAD. The combination of ST-segment depression and abnormal SBP resulted in further improvement of the specificity for detecting CAD. It is concluded that measurement of abnormal increase in postexercise SBP may be a sensitive indicator of gerontal CAD.

Gender differences in the prognostic value of exercise treadmill test characteristics

BACKGROUND

Although exercise treadmill testing (ETT) is less sensitive and specific for diagnosis of coronary disease in women, little is known about gender differences in the prognostic importance of ETT variables.

METHODS

We studied 9,569 consecutive patients (46.8% women) referred for ETT between July 2001 and June 2004 in a community-based system. We assessed the association between ETT variables (exercise capacity, symptoms, ST-segment deviations, heart rate recovery, and chronotropic response) and time to all-cause death and myocardial infarction (MI), adjusting for patient and stress test characteristics. Models were stratified by gender to determine the relationship between ETT variables and outcomes.

RESULTS

In the entire population, exercise capacity and heart rate recovery were significantly associated with all-cause death, whereas exercise capacity, chest pain, and ST-segment deviations were significantly associated with subsequent MI. The relationship between ETT variables and outcomes were similar between men and women, except for abnormal exercise capacity, which had a significantly stronger association with death in men (men: hazard ratio [HR] 2.89 and 95% CI 1.89-4.44, women: HR 0.99 and 95% CI 0.52-1.93, and interaction P = .01), and chronotropic incompetence, which had a significantly stronger relationship with MI in women (men: HR 1.29 and 95% CI 0.74-2.20, women: HR 2.79 and 95% CI 0.94-8.27, and interaction P = .04).

CONCLUSIONS

Although many traditional ETT variables had similar prognostic value in both men and women, exercise capacity was more prognostically important in men, and chronotropic incompetence was more important in women. Future studies should confirm these findings in additional populations.

Cardiovascular outcomes are predicted by exercise-stress myocardial perfusion imaging: Impact on death, myocardial infarction, and coronary revascularization procedures

BACKGROUND

The aim of this study was to determine the impact of myocardial perfusion imaging (MPI) on the outcomes of death, myocardial infarction (MI), and late coronary revascularization procedures.

METHODS

In patients undergoing exercise-stress MPI (January 1, 2003-March 31, 2007), we determined the impact of summed stress score (SSS) and percent left ventricular (LV) ischemia on (a) death or MI and (b) composite of death, MI, or late coronary revascularization occurring more than 90 days post-MPI.

RESULTS

During 35,007 person-years of follow-up among 9,605 patients (mean ± SD age 54.4 ± 13.2 years, 60.3% men), there were 290 deaths, 175 MIs, and 525 coronary revascularization procedures. Of those who attained ≥10 metabolic equivalents (METS) workload, major stress perfusion defects (SSS ≥7) were present in 4.2% overall and in 3.7% without ST-segment shifts, whereas large ischemic defects (≥10% LV ischemia) were present in 1% overall and 0.7% without ST-segment shifts. For those with 1% to 4%, 5% to 9%, and ≥10% LV ischemia, adjusted hazard ratios were 1.40 (95% CI 1.13-1.73, P = .002), 2.07 (95% CI 1.56-2.74, P < .001), and 3.03 (95% CI 2.21-4.16, P < .001) for the outcome of late revascularization, MI, or death versus no ischemia. Summed stress scores ≥7 were associated with increased risk of death or MI, with an adjusted hazard ratio of 1.57 (95% CI 1.16-2.13, P = .004) compared with those with no stress perfusion defects.

CONCLUSION

Although workload ≥10 METS conferred lower frequency of major ischemia (≥10%), %LV ischemia predicted the occurrence of cardiovascular events and death (eg, MI, late coronary revascularization, or death). Presence of a large stress perfusion defect (SSS ≥7) predicted increased risk of MI or death.

Relation of whole blood n-3 fatty acid levels to exercise parameters in patients with stable coronary artery disease (from the heart and soul study)

Dietary intake of n-3 polyunsaturated fatty acids is associated with a lower incidence of cardiovascular events. Mechanisms underlying this association are poorly understood but may include beneficial effects on physical conditioning and vagal tone. We investigated the association of n-3 fatty acid levels to exercise parameters in 992 subjects with stable coronary artery disease. Cross-sectional associations of heart rate recovery time, treadmill exercise capacity, and exercise time with docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) levels were evaluated in multivariable linear and logistic regression models adjusted for demographics, cardiovascular risk factors, co-morbidities, self-reported physical activity, medication use, and left ventricular function. After multivariable adjustment, n-3 fatty acid levels (DHA + EPA) were strongly associated with heart rate recovery (beta 2.1, p = 0.003), exercise capacity (beta 0.8, p <0.0001), and exercise time (beta 0.9, p <0.0001). Increasing levels of (DHA + EPA) were also associated with decreased risk of impaired heart rate recovery (odds ratio 0.8, p = 0.004) and exercise time (odds ratio 0.7, p = 0.01) and trended toward significance for exercise capacity (odds ratio 0.8, p = 0.07). These associations were not modified by demographics, body mass index, smoking, co-morbid conditions, statin use, or β-blocker use (p for interaction >0.1 for all comparisons). In conclusion, an independent association exists between n-3 fatty acid levels and important exercise parameters in patients with stable coronary artery disease. These findings support the hypothesis that n-3 fatty acids may increase vagal tone and physical conditioning.

Prognosis in patients achieving ≥10 METS on exercise stress testing: was SPECT imaging useful?

BACKGROUND

The benefit of myocardial perfusion imaging (MPI) over exercise ECG stress testing alone is unclear in individuals attaining a workload of ≥10 METS. The purpose of this prospective study is to determine mortality and nonfatal cardiac events in patients at either intermediate pretest risk for CAD or patients with known CAD, achieving ≥10 METS regardless of peak exercise heart rate. The authors previously reported a low prevalence of significant ischemia in this patient cohort.

METHODS

Baseline characteristics, ECG stress test findings, and perfusion and function results from quantitative gated (99m)Tc-SPECT MPI were compared by achievement of a maximum age-predicted heart rate ≥85% in 509 consecutive patients who reached ≥10 METS. Events including all-cause and cardiac mortality, non-fatal myocardial infarction (MI), and late revascularization (>4 weeks after MPI) were prospectively collected.

RESULTS

Of the 509 patients achieving ≥10 METS, follow-up for mortality was obtained in 463 (91%). Those lost to follow-up were older and had higher rates of tobacco use. The prevalences of CAD risk factors, prior known CAD, and MPI abnormalities were higher for the 68 patients failing to reach 85% of their target heart rate. The rate of ≥10% left-ventricular (LV) ischemia by MPI remained very low irrespective of attained heart rate (0.6% (3/463)). Six (1.2%) had an LVEF < 40%. Death occurred in 12 (2.6%) patients, one of which was classified as cardiac (0.1%/year). The other 11 deaths were related to cancer. Additionally, there were three nonfatal MIs (0.7 %) and one late revascularization (0.2%). Only one of these patients had any ischemia on MPI. No cardiac event patient had exercise ST depression or ≥5% LV ischemia.

CONCLUSIONS

Thus, patients at intermediate risk for CAD or known CAD achieving ≥10 METS have a very low prevalence of ≥10% LV ischemia and very low rates of cardiac mortality, nonfatal MI, and late revascularization, irrespective of heart rate achieved. Cardiac events did not correlate with abnormalities on the index MPI study. These results suggest that patients who attain ≥10 METS during exercise stress have an excellent prognosis over an intermediate term of follow-up, regardless of peak exercise heart rate achieved. The added value of MPI to standard exercise ECG testing in this population is questionable.

Osteoporosis, osteopenia, and atherosclerotic vascular disease

Older women with low bone mineral density (BMD) have a higher prevalence of atherosclerotic vascular disease (coronary artery disease, ischemic stroke, or peripheral arterial disease) than older women with normal BMD. Three coronary angiographic studies have shown that low BMD is associated with obstructive coronary artery disease. Low BMD has been shown to be associated with stress test-induced myocardial ischemia, reduced exercise capacity, and with aortic valve calcification. Women with osteoporosis have an increased risk for cardiovascular events. Treatment of osteoporosis or osteopenia should include therapeutic measures to prevent cardiovascular events.

Prognostic value of a nine-minute treadmill test in patients undergoing myocardial perfusion scintigraphy

Exercise capacity is an important predictor of risk in known or suspected coronary disease. A negative treadmill test to 9 minutes of the Bruce protocol is often used in the screening process for vocational licensing; myocardial perfusion scintigraphy is an alternative for those unable to exercise, with apparent incremental prognostic power above exercise testing alone. We compared exercise test and myocardial perfusion scintigraphic (MPS) findings and risk of hard cardiac events (median 4 years) in patients completing ≥ 9-minute treadmill exercise. Patients undergoing myocardial perfusion scintigraphy who completed a 9-minute Bruce protocol exercise were identified over a 2-year period. Follow-up was performed by telephone, with case-note review when necessary; this was 97% complete. Five hundred sixteen patients were identified (73% men, median age 53 year). One hundred eighty-one (35%) had known coronary disease. One hundred forty-nine (29%) had a "high-risk" exercise test result (limiting chest pain or ST-segment depression), and 69 (13%) had high-risk MPS findings (>10% myocardium ischemic or ejection fraction <40%). Of 367 patients with a reassuring exercise test result, 38 (10.4%) had high-risk MPS findings. Of 149 with a high-risk exercise test, 118 (79%) had reassuring MPS findings. At median follow-up of 49 months, there were 8 cardiac events (1.6%). Only 2 patients with high-risk exercise test results (1.4%) and 1 with high-risk MPS findings (1.5%) had an event. In conclusion, for patients able to manage a 9-minute Bruce protocol, presence/absence of symptoms or electrocardiographic changes is a poor predictor of MPS findings. Irrespective of test findings, however, subsequent cardiac risk is extremely low. Ability to complete a 9-minute Bruce protocol treadmill exercise may itself provide adequate prognostic reassurance for most purposes.

Timing and significance of exercise-induced left ventricular outflow tract pressure gradients in hypertrophic cardiomyopathy

The relation of exercise-induced left ventricular (LV) outflow tract obstruction to functional capacity in hypertrophic cardiomyopathy (HC) is incompletely defined. Thus, we assessed the patterns of onset of physiologically provoked LV outflow gradients and exercise performance in 74 consecutive patients with HC (age 45 ± 16 years; 74% men) without LV outflow obstruction at rest. The subaortic gradients were measured serially using echocardiography in these 74 patients during maximum, symptom-limited, upright bicycle exercise testing. The time course of the provoked gradients and the relation to exercise performance were assessed. Of the 74 patients, 30 (41%) developed a dynamic LV outflow gradient of ≥30 mm Hg (mean 78 ± 37 mm Hg) during upright exercise testing that correlated highly with the gradients measured with the patients supine during the immediate recovery period (R² = 0.97). The 16 patients in whom outflow obstruction developed rapidly at low exercise levels (≤5 METs) had a significantly reduced exercise capacity (6.1 ± 1.3 vs 8.0 ± 1.6 METs; p <0.01) compared to the other 14 patients in whom obstruction appeared later at greater exercise levels of >5 METs. The timing of the gradient onset was not predictable from the baseline clinical and echocardiographic features, peak exercise LV outflow tract gradient, or symptoms. In conclusion, in patients with HC without outflow obstruction at rest, the earlier onset of LV outflow tract gradients during physiologic exercise was associated with impaired exercise performance. These findings have provided insights into the determinants of functional impairment in HC and support the potential value of exercise echocardiography in the clinical assessment of patients with HC.

Relationship between the percentage of predicted cardiorespiratory fitness and cardiovascular disease risk factors in premenopausal women: a MONET study

OBJECTIVE

To determine the relationships between the percentage predicted cardiorespiratory fitness (%CRF) and the anthropometric and metabolic cardiovascular disease risk factors in asymptomatic, premenopausal women.

METHODS

Data are baseline values obtained in 97 healthy premenopausal women (age 49.9 +/- 1.9 years; body mass index 23.2 +/- 2.2 kg/m(2)) participating in a longitudinal study from 2004 to 2009. The outcome measures were peak oxygen consumption (VO(2) peak), body mass index, body composition (percentage fat, fat mass, fat-free mass), waist circumference, abdominal subcutaneous fat, visceral fat, resting blood pressure and fasting lipids, glucose and insulin levels.

RESULTS

The %CRF was negatively associated with body mass index, fat mass, percentage fat, waist circumference, abdominal subcutaneous fat, visceral fat, triglycerides, triglyceride/high density lipoprotein cholesterol, total cholesterol, total cholesterol/high density lipoprotein cholesterol, fasting insulin levels and HOMA-IR (- 0.59 < or = r < or = - 0.20; 0.01 < p < 0.05) and positively associated with insulin sensitivity index (r = 0.23; p < 0.05). VO(2) peak was associated with the same variables; however, correlations were slightly better (- 0.70 < or = r < or = 0.30; 0.01 < p < 0.05). Stepwise multiple regression analysis showed that %CRF was only independently correlated with plasma triglyceride levels.

CONCLUSION

The results of this study suggest that %CRF was not a major predictor of anthropometric and metabolic variables associated with an increased risk of cardiovascular disease in asymptomatic premenopausal women. Finally, the VO(2) peak is a better predictor than the %CRF to assess the risk of cardiovascular disease in asymptomatic premenopausal women.

Determinants and prognostic implications of cardiac troponin T measured by a sensitive assay in type 2 diabetes mellitus

BACKGROUND

The cardiac troponins are biomarkers used for diagnosis of myocardial injury. They are also powerful prognostic markers in many diseases and settings. Recently introduced high-sensitivity assays indicate that chronic cardiac troponin elevations are common in response to cardiovascular (CV) morbidity. Type 2 diabetes mellitus (T2DM) confers a high risk of CV disease, but little is known about chronic cardiac troponin elevations in diabetic subjects. Accordingly, we aimed to understand the prevalence, determinants, and prognostic implications of cardiac troponin T (cTnT) elevations measured with a high-sensitivity assay in patients with T2DM.

METHODS

cTnT was measured in stored, frozen serum samples from 124 subjects enrolled in the Asker and Bærum Cardiovascular Diabetes trial at baseline and at 2-year follow-up, if available (96 samples available). Results were analyzed in relation to baseline variables, hospitalizations, and group assignment (multifactorial intensive versus conventional diabetes care for lowering CV risk).

RESULTS

One-hundred thirteen (90%) had detectable cTnT at baseline and of those, 22 (18% of the total population) subjects had values above the 99th percentile for healthy controls (13.5 ng/L). Levels at baseline were associated with conventional CV risk factors (age, renal function, gender). There was a strong correlation between cTnT levels at the two time-points (r=0.92, p>0.001). Risk for hospitalizations during follow-up increased step-wise by quartiles of hscTnT measured at baseline (p=0.058).

CONCLUSIONS

Elevations of cTnT above the 99th percentile measured by a highly sensitive assay were encountered frequently in a population of T2DM patients. cTnT levels appeared to be stable over time and associated with conventional CV risk factors. Although a clear trend was present, no statistically robust associations with adverse outcomes could be found.

Incidence of myocardial infarction or stroke or death at 47-month follow-up in patients with diabetes and a predicted exercise capacity <or=85% vs >85% during an exercise treadmill sestamibi stress test

A treadmill exercise sestamibi stress test (TESST) was performed in 609 consecutive diabetic persons with a mean age of 70 years and no history of coronary artery disease (CAD) who were referred for a TESST because of chest pain or dyspnea. Of 609 patients, 301 (49%) had a predicted exercise capacity <or=85% (group A) and 308 (51%) had a predicted exercise capacity >85% (group B). Group A patients had a higher prevalence of myocardial ischemia (43% vs 30%, P=.0005), 2- or 3-vessel obstructive CAD (38% vs 18%, P=.001), myocardial infarction (17% vs 9%, P=.004), death (10% vs 4%, P=.008), and myocardial infarction or stroke or death at 47-month follow-up (21% vs 12%, P=.001). Stepwise Cox regression analysis showed that the only significant independent predictor for the time to development of myocardial infarction or stroke or death was a predicted exercise capacity >85% (hazard ratio, 0.52; 95% confidence interval, 0.34-0.78; P=.002). Diabetic persons with a predicted exercise capacity >85% had a 48% lower chance of myocardial infarction, stroke, or death than those with a predicted exercise capacity <or=85%.

Thrombocyte aggregation, endothelial dysfunction and acute myocardial infarction

<zakljucak> Akutni infarkt miokarda u razvijenim i srednje razvijenim zemljama jedan je od najcescih uzroka mortaliteta i morbiditeta, pa poznavanje patofiziologije ateroskleroze i aterotromboze predstavlja najveci izazov savremenoj medicini. Najcesci uzrok AIM je ateroskleroza epikardnih koronarnih arterija sa posledicnom rupturom i/ili erozijom aterosklerotskog plaka, nastajanjem intrakoronarne tromboze i prekida cirkulacije arterijske krvi u predelu irigacije infarktne arterije. Sklonost ka aterosklerozi ne znaci po pravilu i sklonost ka trombozi, i obrnuto. Mnogobrojni faktori rizika od ishemijske bolesti srca modifikuju funkciju hemostaznog sistema, remete ravnotezu izmedju proagregatornih i antiagregatornih, prokoagulantnih i antikoagulantnih, profibrinolitickih i antifibrinolitickih mehanizama. Na taj nacin genetski uslovljena sklonost ka trombozi potencira se faktorima rizika, sto zajedno vodi ka aterotrombozi i akutnom koronarnom sindromu. Fizicko opterecenje je jedan od faktora rizika od ishemijske bolesti srca. Efekat zavisi od vrste opterecenja, duzine trajanja i stepena utreniranosti bolesnika. Umerena fizicka aktivnost kroz duzi vremenski period ima protektivni znacaj kod bolesnika sa ishemijskom bolescu srca, jer poboljsava funkciju endotela, smanjuje oksidativni stres na nivou endotela, smanjuje broj i aktivnost trombocita kao i aktivnost mnogih faktora koagulacije i na taj nacin smanjuje ucestalost ponovnih koronarnih dogadjaja. Nasuprot tome, akutna fizicka aktivnost dovodi do izrazenog prokoagulantnog stanja sto na terenu disfunkcije endotela i specificnosti hemostaznog sistema moze provocirati ponovnu koronarnu trombozu.

Usefulness of paradoxical systolic blood pressure increase after exercise as a predictor of cardiovascular mortality

Exercise treadmill testing (ETT) is a well-accepted examination for patients with suspected coronary artery disease (CAD), and exercise induced ST-segment deviation is commonly used for CAD detection. However, recent evidence shows that systolic blood pressure (SBP) changes during and after exercise were associated with CAD severity, risk of acute myocardial infarction and stroke, new-onset hypertension, and even cardiovascular mortality. We retrospectively assessed 3,054 patients referred for ETT in 1996. Blood pressure and heart rate were recorded at rest, during peak exercise, and 1 and 3 min after exercise. SBP at 3 min of recovery equal to or higher than that at 1-min of recovery was defined as paradoxical SBP increase. These patients were categorized into 4 groups according to ETT ST-segment change and postexercise SBP change. After 10 years of follow-up, 346 patients (11%) died, with 129 (4%) dying from cardiovascular disease (CVD). Among the 4 groups, patients with ischemic ST-segment change and paradoxical SBP increase were associated with a higher risk for mortality, with odds ratios of 1.86 (95% confidence interval 1.31 to 2.65) for all-cause mortality and 3.18 (95% confidence interval 1.94 to 5.20) for CVD mortality, respectively. Patients with isolated paradoxical SBP increase still had a higher risk of CVD mortality (odds ratio 1.80, 95% confidence interval 1.70 to 3.04), even after controlling other cardiovascular risk factors. In subgroup analysis of 346 mortality subjects, patients with ischemic ST-segment change and paradoxical SBP increase would be more likely to die from CVD. In conclusion, compared with ischemic ST-segment change, paradoxical SBP increase after exercise is an important and significant predictor of CVD mortality.

The relationship between gender and clinical management after exercise stress testing

BACKGROUND

Controversy remains regarding whether gender differences exist in clinical management after exercise treadmill testing (ETT).

METHODS

We studied 7,506 patients (49.8% women) without documented coronary heart disease referred for ETT from July 2001 to June 2004 in a community-based setting. We assessed the relationship between gender and subsequent diagnostic testing (secondary stress testing or coronary angiography) within 6 months after ETT. Secondary outcomes included subsequent stress testing, coronary angiography, and new cardiology visits in the 6-month interval. Multivariable analyses assessed the relationship between gender and these outcomes adjusting for demographic, clinical, and stress test characteristics. In subsequent analyses, patients were stratified by Duke Treadmill Scores (Duke University, Durham, NC).

RESULTS

Compared with men, women referred for ETT were older, had a higher prevalence of some cardiac risk factors, achieved lower peak workloads, and, more often, experienced chest pain or ST-segment changes. After accounting for differences in clinical and ETT parameters, gender was not associated with any subsequent diagnostic testing in the 6 months after ETT (OR 1.0, 95% CI 0.85-1.18). In secondary analyses, women were less likely to undergo angiography (OR 0.63, 95% CI 0.47-0.83) with a trend toward more subsequent stress testing. Stratified analyses revealed less subsequent testing in high-to-intermediate Duke Treadmill Score women compared with men (OR 0.61, 95% CI 0.48-0.79). Women and men were equally likely to die (hazards ratio 0.93, 95% CI 0.61-1.44) in the adjusted survival analysis.

CONCLUSIONS

Overall, women and men equally underwent subsequent diagnostic testing after ETT. Although women were less likely to undergo angiography and higher-risk women were less likely to undergo subsequent testing, adverse events were not higher in women. Given these findings, assumptions regarding gender disparities in clinical management after ETT should be reevaluated in other settings.

Impaired chronotropic response to exercise stress testing in patients with diabetes predicts future cardiovascular events

OBJECTIVES

To assess the association between impaired chronotropic response (CR) and adverse events among patients with diabetes referred for exercise treadmill testing (ETT).

RESEARCH DESIGN AND METHODS

Impaired CR was defined as achievement of <80% of a patient's heart rate reserve. We used multivariable Cox proportional hazards regression to assess the independent association between impaired CR and adverse outcomes adjusting for demographics, comorbidities, and treadmill variables including the Duke Treadmill score.

RESULTS

Of 1,341 patients with diabetes, 35.7% (n = 479) demonstrated impaired CR during ETT. Patients with impaired CR were at increased risk of all-cause mortality, myocardial infarction, or coronary revascularization procedures. In multivariable analyses, impaired CR remained significantly associated with adverse outcomes (hazard ratio 1.53 [95% CI 1.10-2.14]).

CONCLUSIONS

Among patients with diabetes, impaired CR is common during ETT and is associated with adverse outcomes. Impaired CR can be used as another noninvasive tool to risk-stratify patients with diabetes following ETT.