Beta-blockers and inspiratory pulmonary function in chronic heart failure

Area of Science:

• Cardiology
• Pulmonology
• Exercise Physiology

Background:

• Chronic heart failure (CHF) is associated with breathlessness and fatigue, potentially due to impaired respiratory muscle function.
• Beta-blockers are standard CHF treatment but can cause fatigue, necessitating investigation into their respiratory effects.

Purpose of the Study:

• To explore the relationship between respiratory muscle power and functional impairment in CHF patients.
• To assess the impact of long-term beta-blockade on respiratory muscle function and exercise capacity in CHF.

Main Methods:

• Evaluated 52 CHF patients and 25 controls using echocardiography, peak exercise testing, and spirometry (FVC, FEV1, PIF, FIV1).
• 35 CHF patients initiated beta-blocker therapy and were reassessed after one year.
• Analyzed correlations between exercise parameters (pV(O2), anaerobic threshold), respiratory measures (FIV1), and symptom scores (Borg/V(E) slope).

Main Results:

• CHF patients showed significantly lower peak oxygen consumption, exercise time, and anaerobic threshold compared to controls.
• Patients exhibited reduced FEV1, FVC, and FIV1, with FIV1 correlating with exercise capacity and breathlessness perception.
• Beta-blocker therapy improved echocardiographic variables but did not alter pV(O2), PIF, or FIV1; FEV1 significantly decreased.

Conclusions:

• Inspiratory flow rates are diminished in CHF patients, linked to functional capacity and potentially respiratory muscle weakness or reduced lung compliance.
• Long-term beta-blockade does not improve, and may worsen, inspiratory capacity in CHF patients.
• Impaired inspiratory function in CHF is a significant factor contributing to exercise limitation and symptoms.