Changes in subendocardial viability ratio with acute high-altitude exposure and
protective role of acetazolamide.
Author(s): Salvi P(1), Revera M, Faini A, Giuliano A, Gregorini F, Agostoni P, Becerra CG,
Bilo G, Lombardi C, O'Rourke MF, Mancia G, Parati G.
Affiliation(s): Author information:
(1)Department of Cardiology, San Luca Hospital, IRCCS Istituto Auxologico Italiano,
Milan, Italy.
Publication date & source: 2013, Hypertension. , 61(4):793-9
High-altitude tourism is increasingly frequent, involving also subjects with
manifest or subclinical coronary artery disease. Little is known, however, on the
effects of altitude exposure on factors affecting coronary perfusion. The aim of
our study was to assess myocardial oxygen supply/demand ratio in healthy subjects
during acute exposure at high altitude and to evaluate the effect of
acetazolamide on this parameter. Forty-four subjects (21 men, age range: 24-59
years) were randomized to double-blind acetazolamide 250 mg bid or placebo.
Subendocardial viability ratio and oxygen supply/demand ratio were estimated on
carotid artery by means of a validated PulsePen tonometer, at sea level, before
and after treatment, and after acute and more prolonged exposure to high altitude
(4559 m). On arrival at high altitude, subendocardial viability ratio was reduced
in both placebo (from 1.63±0.15 to 1.18±0.17; P<0.001) and acetazolamide (from
1.68±0.25 to 1.35±0.18; P<0.001) groups. Subendocardial viability ratio returned
to sea level values (1.65±0.24) after 3 days at high altitude under acetazolamide
but remained lower than at sea level under placebo (1.42±0.22; P<0.005 versus
baseline). At high altitude, oxygen supply/demand ratio fell both under placebo
(from 29.6±4.0 to 17.3±3.0; P<0.001) and acetazolamide (from 32.1±7.0 to
22.3±4.6; P<0.001), its values remaining always higher (P<0.001) on
acetazolamide. Administration of acetazolamide may, thus, antagonize the
reduction in subendocardial oxygen supply triggered by exposure to hypobaric
hypoxia. Further studies involving also subjects with known or subclinical
coronary artery disease are needed to confirm a protective action of
acetazolamide on myocardial viability under high-altitude exposure.
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