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The highest power sustainable in VO2 and blood lactate steady-state conditions is named "critical power" (CP) and marks the upper limit for prolonged aerobic exercise performance. CP is thus of particular interest for continuous aerobic training prescription, but no data are available as to CP in chronic heart failure (CHF) patients, that is, a population in which aerobic training is a widely accepted nonpharmacologic treatment. The aim of this study was to evaluate CP in a group of CHF and in two groups of age-matched untrained (UT-N) and trained (TR-N) normal subjects.Fifteen untrained CHF, five UT-N, and five TR-N underwent one incremental and five very high/severe-intensity constant-power cardiopulmonary exercise tests (CPT). Power versus time to exhaustion data from CPT were fitted by a hyperbola, whose power asymptote is CP. Subsequently, all participants exercised at CP with blood lactate sampling every 2 min.CP was 80 ± 21, 129 ± 17, and 199 ± 35 W in CHF, UT-N, and TR-N, respectively (all comparisons P0.005). These values corresponded to 66% ± 6%, 66% ± 6%, and 74% ± 3% of peak power in CHF, UT-N, and TR-N, respectively (TR-N vs both CHF and UT-N, P0.05) and to 81% ± 26%, 91% ± 11%, and 83% ± 9% of HR reserve in CHF, UT-N, and TR-N, respectively (NS). All participants exercised for 30 min in VO2, blood lactate, ventilation, and HR steady-state conditions at CP but not at the lowest-power CPT (CP ~ 10%).The upper intensity limit for prolonged aerobic exercise, that is, CP, is equal to 65% of peak power in CHF patients. This finding provides a physiologically meaningful reference for continuous aerobic training prescription in this population.

To investigate the effects of exercise training (ET) on left ventricular (LV) volumes, cardiopulmonary functional capacity and N-terminal pro-brain natriuretic peptide (NT-proBNP) levels in postinfarction patients with moderate LV dysfunction.Sixty-one postinfarction patients were randomized into two groups: group T [n=30, LV ejection fraction (EF) 41.6+/-11.3%, mean+/-SD] entered a 6-month ET programme, whereas group C (n=31, EF 42.0+/-7.6%, P=NS) did not. NT-proBNP assay, Doppler-echocardiography and cardiopulmonary exercise test were performed upon enrolment and at sixth months.At sixth months, trained patients showed an improvement in workload (+26%, P0.001), Vo2peak (+31%, P0.001), LV end-diastolic volume index (LVEDVI; -9%, P0.001), a reduction in NT-proBNP (-71%, P0.001) and a significant correlation between changes in NT-proBNP and in LVEDVI (r=0.858, P0.001). Baseline NT-proBNP correlated with changes in LVEDVI in both trained (r=0.673, P0.001) and untrained (r=0.623, P0.001) patients. Group C showed unfavourable LVEDVI dilation (+8%, P0.001; T vs. C group, P0.001) and a smaller reduction in NT-proBNP (-40%, P0.001; T vs. C group, P0.001).Six month ET induced a favourable LV remodelling and a marked fall in NT-proBNP that could predict LV remodelling in postinfarction patients with moderate LV dysfunction.

Background: This study was addressed to verify if Telecardiology (TC) improves the results of Cardiac Rehabilitation in patients following a home-based Cardiac Rehabilitation Program (CRP) after acute myocardial infarction (AMI). Materials and Methods: We studied three groups of patients after AMI: Group A (control group): 15 patients, who followed a standard in-hospital CRP of 3 weekly sessions of 2 months duration; Group B (study group): 15 patients, who were enrolled in a home-based CRP of similar duration and were monitored by TC with the aid of an ecg-device (Sorin Life Watch CG 6106); Group C (second control group): 15 patients, who followed a home-based CRP without ecgmonitoring by TC. All patients performed a symptom-limited exercise testing at the beginning of the CRP. Psychometric data (STAI-Y1, STAI-Y2, BDI) were also evaluated. At the end of the CRP all patients underwent repeated exercise testing and psychometric evaluation. Results: TC applied to the home-based CRP was associated with a good compliance to the program. Compared to Group C, in Group B we observed an increase of maximal heart rate, exercise duration, maximal work-load, and an improvement of anxiety, a trend to reduction of depression, and an improvement of quality of life. These results were very similar to Group A patients following a hospital-based CRP. Conclusions: TC improves compliance, functional capacity and psychological profile of patients undergoing a home-based CRP, compared to patients enrolled in a homebased CRP without ecg-monitoring by Telecardiology.

Introduction N-terminal-pro-brain (B-type) natriuretic peptide (NT-pro-BNP) is a peptide hormone released from ventricles in response to myocyte stretch. The aim of the study was to investigate the influence of exercise training on plasma NT-pro-BNP to verify if this parameter could be used as a biological marker of left ventricular remodelling in myocardial infarction patients undergoing an exercise training programme.Methods Forty-four patients after myocardial infarction were enrolled into a cardiac rehabilitation programme, and were randomized in two groups of 22 patients each. Group A patients followed a 3-month exercise training programme, while group B patients received only routine recommendations. All patients underwent NT-pro-BNP assay, and cardiopulmonary exercise test before hospital discharge and after 3 months.Results In Group A, exercise training reduced NT-pro-BNP levels (from 1498 +/- 438 to 470 +/- 375pg/ml, P = 0.0026), increased maximal (V-O2peak +4.3 +/- 2.9 ml/kg per min, P < 0.001; Power(max) +38 +/- 7, P < 0.001) exercise parameters and work efficiency (Power(max)/V-O2peak + 1.3 +/- 0.4 Power/ml per kg per min, P < 0.001); there was also an inverse correlation between changes in NT-pro-BNP levels and in V-O2peak (r = -0.72, P < 0.001), E-wave (r = -0.51, P < 0.001) and E/A ratio (r = 0.59, P < 0.001). In group B, at 3 months, no changes were observed in NT-pro-BNP levels, exercise and echocardiographic parameters.Conclusion Three months exercise training in patients with moderate left ventricular systolic dysfunction after myocardial infarction induced a reduction in NT-pro-BNP levels, an improvement of exercise capacity and early left ventricular diastolic filling, without negative left ventricular remodelling. Whether the reduction of NT-pro-BNP levels could be useful as a surrogate marker of favourable left ventricular remodelling at a later follow-up remains to be further explored.

Heart rate recovery (HRR) is a marker of vagal tone that is a powerful predictor of mortality in patients with coronary artery disease.This study aims at evaluating the effects of long-term exercise training on HRR after acute myocardial infarction (AMI), in order to clarify whether prolonged exercise training could maintain a long-term improvement of HRR.Forty-four patients after AMI were enrolled in a 3-month hospital-based exercise training programme. At the end, patients were subdivided into two groups: group A (n=22), patients discharged with a specific home-based exercise training programme and instructions for improving leisure-time physical activity; group B (n=22), patients discharged with generic instructions to maintain physical activity. All patients underwent a cardiopulmonary exercise test before, at the end of 3 months exercise training and at 6 months follow-up.At the end of the hospital-based exercise training programme we observed an increase in peak oxygen consumption [VO2peak; from 13.9+/-3.6 to 18+/-2.7 ml/kg per min (A) and from 14.1+/-3.9 to 17.9+/-2.1 ml/kg per min (B), P0.001] and in HRR [from 17.1+/-1.8 to 23.4+/-1.4 beats/min (A), and from 18.8+/-2.1 to 24.3+/-1.9 beats/min (B), P0.001]. At 6 months' follow-up we observed a further improvement in VO2peak (from 18.0+/-2.7 to 20.3+/-2.7 ml/kg per min, P0.001) and in HRR (from 23.4+/-1.4 to 27.8+/-2.1 beats/min, P0.001) in group A, but a significant decrease in VO2peak and in HRR in group B (P0.001).Long-term exercise training is useful for maintaining or improving the beneficial results of the standard 3-month exercise training programme on cardiovascular capacity and HRR. This observation may bear beneficial prognostic effects on patients after AMI.