A non-invasively determined surrogate of cardiac power ('circulatory power') at peak exercise is a powerful prognostic factor in chronic heart failure.

OBJECTIVES: This study was designed to assess the prognostic value of a new variable derived from a cardiopulmonary exercise test, the circulatory power, a surrogate of cardiac power, at peak exercise, in patients with chronic heart failure. BACKGROUND: Peak exercise cardiac power and stroke work are invasive parameters with recently proven prognostic value. It is unclear whether these variables have better prognostic value than peak oxygen uptake (VO(2)). METHODS: The study population comprised 175 patients with chronic heart failure (ejection fraction <45%) who underwent a cardiopulmonary exercise test. Circulatory power and circulatory stroke work were defined as the product of systolic arterial pressure and VO(2) and oxygen pulse, respectively. Prognostic value was assessed by survival curves (Kaplan-Meier method) and uni- and multivariate Cox analyses. RESULTS: With a mean follow-up of 25+/-10 months, ejection fraction, heart rate, systolic arterial pressure, peak VO(2), VCO(2), the anaerobic threshold, minute ventilation, the ventilatory equivalents of oxygen and carbon dioxide, the half times of VO(2) and VCO(2) recoveries, and the circulatory stroke work and power predicted outcome. Multivariate analysis demonstrated that the peak circulatory power (chi-square=19.9, P<0.001) (but not peak circulatory stroke work) was the only variable predictive of prognosis. CONCLUSION: The prognostic value of cardiopulmonary exercise tests in heart failure patients can be improved by assessing a new variable, the circulatory power - a surrogate of cardiac power - at peak exercise.

Evidence of cardiac myolysis in severe nonischemic heart failure and the potential role of increased wall strain.

BACKGROUND: Myocyte death could play a role in heart failure (HF) irrespective of the presence of coronary artery disease. The study aimed to assess this hypothesis by use of the cardiac troponin I (cTnI) assay. METHODS AND RESULTS: Seventy-one patients with nonischemic HF, New York Heart Association (NYHA) class II-IV, with a normal coronary angiogram and after exclusion of myocardiopathies were evaluated in the study. The control group included 9 healthy subjects and 15 patients hospitalized for severe noncardiac dyspnea. Cardiac TnI concentrations were determined at admission with a research reagent (cTnIus) characterized by a detection limit of 0.026 ng/mL and a high analytic sensitivity of 0.002 ng/mL. cTnIus levels were more than 0.026 ng/mL in 19 HF patients, ranging between 0.027 and 0.463 ng/mL, whereas no cTnIus level was detectable in the control group. With use of a reference assay, only 2 HF patients had abnormal cTnI values. Severe HF was observed in 17 of these 19 patients, assessed by NYHA class IV or by the presence of pulmonary edema. Patients with an increased cTnIus level had a more restrictive mitral Doppler pattern (P <.001) and a more distinctive left ventricular (LV) concentric remodeling (P <.0001), whereas LV ejection fraction was similar in both HF groups. The increased cTnIus level was also associated with a LV wall strain biologic marker (ie, an increased brain natriuretic peptide plasma level) (P <.001). CONCLUSIONS: cTnI assay is a promising biochemical method for detecting cardiac myolysis in HF, independent of the presence of coronary artery disease. This subtle myolysis could be in part related to the severely increased LV wall strain.

Effects of short-term exercise training in patients with heart failure.

Heart failure is a debilitating disorder which limits exercise capacity and produces a poor quality of life. The present study was designed to determine the effects of an exercise training program on patients with CHF NYHA functional class II-III, attributed to left ventricular systolic dysfunction and dilated left ventricle. Twenty-two ambulatory male patients with stable CHF were randomised to a training (n = 15) and a control group (n = 7). A symptom limited ramp cardiopulmonary exercise test with gas exchange analysis was performed at baseline after 4 and 8 weeks. The training group underwent an exercise training program at 50% of peak oxygen uptake for eight weeks. The control group was not exercised. After 8 weeks, compared with baseline, there were statistically significant increase in peak oxygen uptake, peak workload, anaerobic threshold, oxygen pulse, RPP, ventilation and the duration of the test only in trained patients. The reduction in scores tested by the Minnesota Living with Heart Failure questionnaire (p < 0.001) and Borg dyspnea rating score (p < 0.001) reflect the reduction of symptoms and the improvement in health-related quality of life. Carefully selected patients with moderate to severe CHF can achieve significant improvements of exercise capacity and quality of life with exercise training and can safely participate in a conditioning program.

Analysis of the results from an early low-level predischarge and late symptom-limited exercise tests and coronary angiographic examination in patients with uncomplicated myocardial infarction.

The aim of our study was to evaluate the prognostic value of an early predischarge and late symptom-limited exercise tests as opposed to the evidence from the coronary angiographic examination. Twenty patients with an uncomplicated myocardial infarction were studied with an early predischarge exercise test (14-21 days) and a following postdischarge late symptom-limited veloergometric test. All the patients underwent an exercise test designed according to the protocol of the International Health Organization. A coronary angiographic examination was carried out in all the studied patients. Thirteen of the patients were with two positive veloergometric tests and significant stenosis from the selective coronary angiography. Seven of the patients had two negative tests. Two of them did not have significant coronary stenosis from the angiografic assessment. Generally 40% of the patients undergoing late exercise test reached a higher workload. There was no significant difference between the results from an early predischarge and late symptom-limited veloergometric test. A higher physical work load reached during the late exercise test did not show an improved coronary blood flow. Positive early and late exercise tolerance tests proved significant coronary stenosis. A negative exercise test did not exclude significant coronary stenosis.

Comprehensive assessment of ventilatory functions of patients with chronic heart failure.

OBJECTIVE: A comprehensive assessment of the ventilatory functions of patients with chronic heart failure (CHF) both at rest and during a cardiopulmonary exercise test (CPET). We studied 42 males, divided into two groups--patients with CHF (n = 21) and age, weight, height and BMI matched healthy controls (n = 21). All subjects underwent a symptom-limited ramp CPET, arterial blood gas analysis, and complex functional examination of the pulmonary system. Subjective rating of dyspnea and exertion were measured by the Borg and ATS dyspnea scales. CHF patients showed a slight, but statistically significant decrease of the spirographic and diffusion parameters, as well as of the indices of respiratory muscle strength. There were no changes in blood gases and in tidal breathing parameters. The exercise capacity was markedly reduced (VO2peak ml.min-1 1352 +/- 335 CHF patients vs 2077 +/- 276 healthy controls; p < 0.001) and the anaerobic threshold occurred earlier (< 40% of predicted VO2peak) during CPET in CHF patients. The increase in VE/VCO2 in CHF patients (35.7 +/- 5.1 CHF; 28.9 +/- 2.5 HC, p < 0.001) indicates a compromised ventilatory efficiency which leads to a higher dyspneic cost of exercise (Borg peak 9.5 +/- 1.03 CHF; 6.0 +/- 1.28 HC; p < 0.001) as compared with healthy controls.

Cardiopulmonary stress test--general characteristics and clinical value.

Dyspnea on exertion and exercise intolerance are common problems in many conditions and diseases. Cardiopulmonary exercise testing makes possible to assess the exercise response in patients with abnormalities which are either underestimated or not detectable at rest. The method permits simultaneous assessment of circulatory and ventilatory reserves and can determine aerobic capacity, anaerobic threshold, the ventilatory response and the appearance of hypoxemia. Peak exercise oxygen uptake is the variable most often used, because of its physiological and prognostic value. One can use this information to evaluate the nature and severity of disease, its progression over time and its response to therapy.