Clinical Implications for Exercise at Altitude Among Individuals With Cardiovascular Disease: A Scientific Statement From the American Heart Association.

An increasing number of individuals travel to mountainous environments for work and pleasure. However, oxygen availability declines at altitude, and hypoxic environments place unique stressors on the cardiovascular system. These stressors may be exacerbated by exercise at altitude, because exercise increases oxygen demand in an environment that is already relatively oxygen deplete compared with sea-level conditions. Furthermore, the prevalence of cardiovascular disease, as well as diseases such as hypertension, heart failure, and lung disease, is high among individuals living in the United States. As such, patients who are at risk of or who have established cardiovascular disease may be at an increased risk of adverse events when sojourning to these mountainous locations. However, these risks may be minimized by appropriate pretravel assessments and planning through shared decision-making between patients and their managing clinicians. This American Heart Association scientific statement provides a concise, yet comprehensive overview of the physiologic responses to exercise in hypoxic locations, as well as important considerations for minimizing the risk of adverse cardiovascular events during mountainous excursions.

Blood pressure and hypertension in people living at high altitude in Nepal.

This study aimed to describe blood pressure (BP) and hypertension (HT) in samples of high altitude populations of Nepal and to explore associations of systolic and diastolic BP with altitude. This was a cross-sectional survey of cardiovascular disease and associated risk factors among 521 people living at four different altitude levels, all above 2800 m, in the Mustang and Humla districts of Nepal. Data on BP was available for all 521 participants. Systolic and diastolic BP levels were highest at the altitude of 3620 m (the highest area surveyed) but did not consistently increase with altitude. Using the cut-point of ≥ 140/90 mmHg (systolic/diastolic), the prevalence of HT (or on anti-hypertensive medication) was 46.1%, 40.9% and 54.5%, respectively, at 2800, 3270 and 3620 m of Mustang district, and 29.1% at 2890 m of Humla district. In a multivariate model adjusting for potential confounders, there was strong evidence of a relationship between systolic BP and altitude; mean systolic BP increased by 15.6 mmHg (95% CI: 4.0-27.2), P = 0.009 for every 1000 m elevation. Although diastolic BP and the probability for HT or on anti-hypertensive medication also tended to increase with increasing altitude levels, there was no evidence of a relationship. In the present study three out of four communities living at higher altitude levels showed a greater prevalence of HT among those aged 30 years or older compared with the overall national data. These findings indicate a probable high risk of raised BP in high altitude populations in Nepal.

Lipid Profiles, Glycated Hemoglobin, and Diabetes in People Living at High Altitude in Nepal.

This study aimed to describe lipid profiles and the distribution of glycated hemoglobin (HbA1c) in a sample of a high altitude population of Nepal and to explore associations between these metabolic risk variables and altitude. A cross-sectional survey of cardiovascular disease and associated risk factors was conducted among 521 people living at four different altitude levels, all above 2800 m, in the Mustang and Humla districts of Nepal. Urban participants (residents at 2800 m and 3620 m) had higher total cholesterol (TC) and triglyceride (TG) than rural participants. A high ratio of TC to high-density lipoprotein-cholesterol (HDL) (TC/HDL ≥ 5.0) was found in 23.7% (95% CI 19.6, 28.2) and high TG (≥1.7 mmol/L) in 43.3% (95% CI 38.4, 48.3) of participants overall. Mean HbA1c levels were similar at all altitude levels although urban participants had a higher prevalence of diabetes. Overall, 6.9% (95% CI 4.7, 9.8) of participants had diabetes or were on hypoglycaemic treatment. There was no clear association between lipid profiles or HbA1c and altitude in a multivariate analysis adjusted for possible confounding variables. Residential settings and associated lifestyle practices are more strongly associated with lipid profiles and HbA1c than altitude amongst high altitude residents in Nepal.

Electrocardiography in people living at high altitude of Nepal.

OBJECTIVE: The main objective of this study was to estimate the prevalence of coronary heart disease (CHD) of high-altitude populations in Nepal determined by an ECG recordings and a medical history. METHODS: We carried out a cross-sectional survey of cardiovascular disease and risk factors among people living at four different altitude levels, all above 2800 m, in the Mustang and Humla districts of Nepal. 12-lead ECGs were recorded on 485 participants. ECG recordings were categorised as definitely abnormal, borderline or normal. RESULTS: No participant had Q waves to suggest past Q-wave infarction. Overall, 5.6% (95% CI 3.7 to 8.0) of participants gave a self-report of CHD. The prevalence of abnormal (or borderline abnormal) ECG was 19.6% (95% CI 16.1 to 23.4). The main abnormalities were: right axis deviation in 5.4% (95% CI 3.5 to 7.7) and left ventricular hypertrophy by voltage criteria in 3.5% (95% CI 2.0 to 5.5). ECG abnormalities were mainly on the left side of the heart for Mustang participants (Tibetan origin) and on the right side for Humla participants (Indo-Aryans). There was a moderate association between the probability of abnormal (or borderline abnormal) ECG and altitude when adjusted for potential confounding variables in a multivariate logistic model; with an OR for association per 1000 m elevation of altitude of 2.83 (95% CI 1.07 to 7.45), p=0.03. CONCLUSIONS: Electrocardiographic evidence suggests that although high-altitude populations do not have a high prevalence of CHD, abnormal ECG findings increase by altitude and risk pattern varies by ethnicity.

Injury and Mortality in Young Nepalese Migrant Workers: A Call for Public Health Action.

Approximately 3.5 million Nepalese are working as migrant workers in the Gulf countries, Malaysia, and India. Every year there are more than 1000 deaths and many hundreds cases of injuries among Nepalese workers in these countries excluding India. A postmortem examination of migrant workers is not carried out in most of these countries, and those with work-related injuries are often sent back to home. Uninsured migrant workers also do not have easy access to health care services in host countries due to the high medical and hospital fees. Greater efforts are needed to protect the health and well-being, labor rights, and human rights of migrant workers from Nepal and other South-Asian nations. There is a need to enforce universal labor laws in these countries and to develop accurate records of mortality and morbidity and their causes.

Blood Pressure and Hypertension in Adults Permanently Living at High Altitude: A Systematic Review and Meta-Analysis.

Aryal, Nirmal, Mark Weatherall, Yadav Kumar Deo Bhatta, and Stewart Mann. Blood pressure and hypertension in adults permanently living at high altitude: a systematic review and meta-analysis. High Alt Med Biol. 17:185-193, 2016.-The objective of this study was to estimate the associations between altitude and mean blood pressure (BP) (or prevalence of hypertension [HT]) in adults who live permanently at high altitude. A literature search was conducted in December 2014 using PubMed, Scopus, and OvidSP (MedLine and EMBASE) databases to identify relevant observational studies. Inclusion criteria were reports of studies in populations permanently living at an altitude of ≥2400 m and in those 18 years or older. Meta-regression was used to estimate the association between average BP and HT and altitude. We identified 3375 articles and inclusion criteria were met for 21 reports, which included a total of 40,854 participants. Random-effects meta-regression estimated that for every 1000 m elevation the average systolic BP (SBP) (95% confidence interval [CI]) increased by 17 mmHg (0.2 to 33.8), p = 0.05 and diastolic BP (DBP) by 9.5 mmHg (0.6 to 18.4), p = 0.04 in participants with Tibetan origin. By contrast, in participants with non-Tibetan origin, average SBP decreased by 5.9 mmHg (-19.1 to 7.3), p = 0.38 and DBP by 4 mmHg (-13 to 5), p = 0.38. The odds ratios (95% CI) for the proportion of participants with HT per 1000 m increment in the altitude were 2.01 (0.37 to 11.02), p = 0.446 and 4.05 (0.07 to 244.69), p = 0.489 for Tibetan and non-Tibetan participants, respectively. Sensitivity analysis excluding two studies with older participants (≥60 years) reversed the direction of this effect in non-Tibetans with odds ratio (95% CI) of 0.10 (0.004 to 2.22) per 1000 m, p = 0.143. Overall, this review suggests weak association between BP and altitude in Tibetan origin populations.