Considerations on Safety and Treatment of Patients with Chronic Heart Failure at High Altitude

Abstract

Prognosis and quality of life of chronic heart failure (HF) patients have greatly improved over the last decade. Consequently, many patients are willing to spend leisure time at altitude, usually <3500 m, but their safety in doing so is undefined. HF is a syndrome that often has relevant co-morbidities, such as pulmonary hypertension, COPD, unstable cardiac ischemia, and anemia. HF co-morbidities may per se impede a safe stay at altitude. Exercise at simulated altitude is associated with a reduction in performance, which is greater in HF patients than in normal subjects and greater in patients with most severe HF. In normal subjects, the reduction in performance is ∼2% every 1000 m altitude increase, whereas it is 4% and 10% in HF patients with normal or slightly diminished exercise capacity and in HF patients with markedly diminished exercise capacity. On-field experience with HF patients at altitude is limited to subjects driven to altitude (3454 m) for a few hours. The data showed a reduction in exercise capacity similar to that reported at simulated altitude. "Optimal" HF treatment in patients spending time at altitude is likely different from optimal treatment at sea level, particularly as regards β-blockers. Carvedilol, a β1-β2-α-blocker, reduces the hypoxic ventilatory response through a reduction of the chemoreflex response, and it reduces alveolar-capillary gas diffusion, which is under control by β2-receptors. These actions are not shared by selective β1-blockers such as bisoprolol and nebivolol, which should be preferred for treatment of HF patients willing to spend time at altitude. In conclusion, spending time at altitude (<3500 m) is safe for HF patients, provided that subjects are free of co-morbidities that may directly interfere with the adaptation to altitude. However, HF patients experience a reduction of exercise capacity in proportion to HF severity and altitude. Finally, HF patients should undergo a specific "altitude-tailored treatment" to avoid pharmacological interference with altitude adaptation mechanisms.

Aging, High Altitude, and Blood Pressure: A Complex Relationship

“…Of note, the reduced exercise performance during HA exposure, similar to what has been shown in HF patients, may be favorably modulated by selective beta1-blockers such as bisoprolol and nebivolol (Valentini et al, 2012;Agostoni, 2013).…”

Ambulatory Blood Pressure in Untreated and Treated Hypertensive Patients at High Altitude

“…As a result, the few recommendations published on the management of hypertensive subjects planning to spend time at high altitude for either leisure or work are largely based on experts' opinion rather than on evidence. 2,[11][12][13][14] Both angiotensin receptor blockers (ARBs) and dihydropyridine calcium antagonists are widely used for the monotherapy of hypertension, and their combination has been included among the preferred therapeutic choices by recent Abstract-Blood pressure increases during acute exposure to high altitude in healthy humans. However, little is known on altitude effects in hypertensive subjects or on the treatment efficacy in this condition.…”

Altitude Travel in Patients With Pulmonary Hypertension: Randomized Pilot-Trial Evaluating Nocturnal Oxygen Therapy

“…Clinical data and particularly randomized-controlled trials on patients with cardiorespiratory disorders, such as heart failure (HF) or COPD, traveling at altitude is scarce, and no data are available for patients with PH ( 6 ). In HF, altitude exposure is not recommended if patients are unstable ( 23 ) or suffer from comorbidities that may directly interfere with the adaptation to altitude ( 24 ). Only few studies are available in clinically stable patients with HF on optimal medical treatment investigating short exposure to real altitude or normobaric hypoxia simulating altitude near sea level ( 24 , 25 ).…”

“…In HF, altitude exposure is not recommended if patients are unstable ( 23 ) or suffer from comorbidities that may directly interfere with the adaptation to altitude ( 24 ). Only few studies are available in clinically stable patients with HF on optimal medical treatment investigating short exposure to real altitude or normobaric hypoxia simulating altitude near sea level ( 24 , 25 ). One of those studies assessed exercise capacity in 29 optimally treated and stable patients with severe HF [ejection fraction <40%, peak oxygen uptake (peak VO 2 ) > 50% predicted] traveling to 3,454 m (4–5-h stay at altitude) and revealed a reduction of 22.2% in the peak VO 2 ( 26 ).…”