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cardiac magnetic resonance ; left ventricle ; physical training
Abstract:
Chronic heart failure due to its incidence and unfavorable prognosis is an increasingly important clinical, epdemiological and economic problem. Despite progress in pharmacological and invasive treatment the outcomes are still unsatisfactory and long-term prognosis is poor. Physical training is a well-known complementary modality in the treatment of chronic heart failure, however many aspects require further studies. One of them is the impact on myocardial morphology and function. Available evidence shows that physical training modifies the failing heart. The purpose of the present study was to evaluate the effect of out-patient 6-month physical training on left ventricle, exercise capacity, skeletal muscle metabolism in lower extremities and safety issues in patients with chronic ischemic heart failure. Material and Methods: the study was conducted in 50 patients (38 men, 12 women, man age 60.1±9.2 years) with chronic ischemic heart failure NYHA class II and III and left ventricular ejection fraction < 35%. The entry criterion was clinical stabilization on standard treatment at least 6 weeks prior to the study. All patients received a beta-blocker (carvedilol) and ACE inhibitor (lisinopril) in the highest tolerated doses. Drugs from other classes were used optionally. The patients, according to place of residence, were divided into two groups: undergoing 6-month physical tr ; aining (A - 25 patients) and without training - control group (B - 25 patients, who lived far from the training center). In both groups the following studies were performed at baseline: spiroergometric test, echocardiography, MRI with evaluation of selected morphological and functional left ventricular parameters and MR spectroscopy of femoral skeletal muscles (’HMRS). At baseline the groups were comparable. Physical training in group A was carried out in the Out-patient Rehabilitation Clinic of the I Cardiac Department CMUJ in Krakow for 6 months, three times a week, with sessions of 60 min each (a mean of 72 training units for each patient). Each training unit consisted of general exercises and bicycle training with gradually incremented workload limited by the achievement of 80% predicted heart rate at VOzpeak achieved at baseline spiroergometry. Results: All patients completed the 6-month observation. No unwanted effects were found in either group. In 10 training patients and 13 controls (40% vs. 52%, p=NS) it was necessary to modify the pharmacological therapy due to transient aggravation of heart failure symptoms. At 6 months exercise capacity improved significantly in group A: peak oxygen consumption increased from 14.6±2.9 to 19.2±3.8.ml/kg/min (p<0.01), and ventilatory equivalent for carbon dioxide decreased from 38.4±4.1 to 34.3±3.9 (p<0.05). The aerobic phase was ; longer: maximum oxygen consumption at anaerobic threshold at baseline was 10.4±2.5, whereas after training 12.9±3.2 ml/kg/min (p<0.05). The duration o f exercise testing was also markedly prolonged from 378±44 to 752±85 s (p<0.01) and maximal workload increased from 105.6±23.4 at baseline to 143.8±31.7 Watts after training (p<0.01). Left ventricular parameters did not change significantly in trained patients at 6 months, although there was a trend toward better functional indices, global and regional wall motion (ejection fraction increased from 27.4±4.7 to 31.2±5.6%, p = 0.065; end-diastolic volume decreased from 122.6±24.3 to 111.8±28.2 ml/m2, p = 0.061; segmental wall motion index decreased from 2.17±0.6 to 1.84±0.4, p = 0.056). In the controls, exercise capacity and left ventricular parameters both on echocardiography and MR remained unchanged. MR spectroscopy of femoral skeletal muscles ('HMRS) in trained patients showed a significant increase in Crtot/TMA+Crtot+Lip (0.18±0.06 before vs. 0.29±0.08 after training, p< 0.05) corresponding to muscle total creatine content which plays an important role in skeletal muscle energy metabolism. There were no changes in the contents indexes for lipids and substances composed of trimethylamine groups. The controls did not show significant differences in parameters relating to biochemical composition of femoral skeletal muscles. C ; onclusions: an out-patient 6-month physical training in patients with ischemic, chronic heart failure is a safe modality. Training significantly improves exercise capacity and favorably affects skeletal muscle metabolism in lower extremities. There was no negative impact on left ventricular morphological parameters, and a trend towards improvement of functional parameters in MR may suggest an antiremodelling effect of training in patients with chronic ischemic heart failure. Magnetic resonance appears a useful tool for monitoring changes in the myocardium and skeletal muscles in heart failure patients undergoing regular physical training.