Heart failure
Effects of Exercise Training on Myocardial Blood Flow Reserve in Patients With Heart Failure and Left Ventricular Systolic Dysfunction

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Exercise training has been shown to be effective in improving exercise capacity and quality of life in patients with heart failure and left ventricular (LV) systolic dysfunction. Real-time myocardial contrast echocardiography (RTMCE) is a new technique that allows quantitative analysis of myocardial blood flow (MBF). The aim of this study was to determine the effects of exercise training on MBF in patients with LV dysfunction. We studied 23 patients with LV dysfunction who underwent RTMCE and cardiopulmonary exercise testing at baseline and 4 months after medical treatment (control group, n = 10) or medical treatment plus exercise training (trained group, n = 13). Replenishment velocity (β) and MBF reserves were derived from quantitative RTMCE. The 4-month exercise training consisted of 3 60-minute exercise sessions/week at an intensity corresponding to anaerobic threshold, 10% below the respiratory compensation point. Aerobic exercise training did not change LV diameters, volumes, or ejection fraction. At baseline, no difference was observed in MBF reserve between the control and trained groups (1.89, 1.67 to 1.98, vs 1.81, 1.28 to 2.38, p = 0.38). Four-month exercise training resulted in a significant increase in β reserve from 1.72 (1.45 to 1.48) to 2.20 (1.69 to 2.77, p <0.001) and an MBF reserve from 1.81 (1.28 to 2.38) to 3.05 (2.07 to 3.93, p <0.001). In the control group, β reserve decreased from 1.51 (1.10 to 1.85) to 1.46 (1.14 to 2.33, p = 0.03) and MBF reserve from 1.89 (1.67 to 1.98) to 1.55 (1.11 to 2.27, p <0.001). Peak oxygen consumption increased by 13.8% after 4 months of exercise training and decreased by 1.9% in the control group. In conclusion, exercise training resulted in significant improvement of MBF reserve in patients with heart failure and LV dysfunction.

Section snippets

Methods

From June 2005 to November 2007, we prospectively enrolled 31 consecutive patients with stable primary heart failure and LV dysfunction who underwent stress RTMCE before and after 4-month exercise-based rehabilitation with medical treatment or medical treatment alone. Inclusion criteria were symptoms of heart failure for ≥1 year,5 optimized medical treatment, and LV ejection fraction <45%. Exclusion criteria were inability to exercise, malignant arrhythmias, ischemic cardiomyopathy, second- or

Results

Of the 31 enrolled patients, 16 were randomized to the trained group and 15 to the control group. Of the 16 patients in the trained group, 1 had intense dyspnea during dipyridamole resulting in stress interruption and 2 did not complete the training program due to noncardiac reasons. Of the 15 patients in the control group, 5 did not agree to repeat RTMCE and cardiopulmonary exercise testing after 4 months and were excluded. The final population was constituted by 23 patients. Their clinical

Discussion

In this study we demonstrated, for the first time, that exercise training in a supervised hospital-based setting resulted in a significant increase of microvascular reserve, despite no improvement in LV ejection fraction in patients with heart failure and LV dysfunction. Heart failure is a major public health problem in the entire world. In 1990, Coats et al11 demonstrated a beneficial effect of exercise training on exercise tolerance, peak oxygen consumption, and symptoms in a crossover trial

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    This study received a grant from the Fundação de Amparo à Pesquisa do Estado de São Paulo, São Paulo, Brazil.

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