Abnormal blood-pressure response to exercise and oxygen consumption in patients with hypertrophic cardiomyopathy.
BACKGROUND
Abnormal blood-pressure response during exercise occurs in about one third of patients with hypertrophic cardiomyopathy (HCM), and it has been associated with a high risk of sudden cardiac death. We assessed the hemodynamics of exercise in HCM patients with abnormal blood-pressure response by using ambulatory radionuclide monitoring (VEST) of left-ventricular (LV) function, and exercise tolerance by oxygen consumption.


METHODS
Twenty-two HCM patients underwent treadmill exercise during VEST monitoring. A cardiopulmonary exercise test was performed a few days after. The VEST data were averaged for 1 minute. Stroke volume, cardiac output, and systemic vascular resistance were expressed as percent of baseline. Exercise tolerance was assessed as maximal oxygen consumption.


RESULTS
In eight HCM patients (36%) with an abnormal blood-pressure response, end-systolic volume increased more (52% +/- 21% vs 31% +/- 28%, P = .012), and the ejection fraction (-31% +/- 17% vs -14% +/- 22%, P = .029) and stroke volume (-21% +/- 21% vs 3% +/- 28%, P = .026) fell more, than in patients with normal response. Cardiac output increased less in the former patients (49% +/- 44% vs 94% +/- 44%, P = .012). Systemic vascular resistance decreased similarly, irrespective of blood-pressure response (-28% +/- 26% vs -34% +/- 26%, P = N.S.). Percent of maximal predicted oxygen consumption was lower in HCM patients with an abnormal blood-pressure response (63% +/- 11% vs 78% +/- 15%, P = .025).


CONCLUSIONS
In HCM patients, abnormal blood-pressure response was associated with exercise-induced LV systolic dysfunction and impairment in oxygen consumption. This may cause hemodynamic instability, associated with a high risk of sudden cardiac death.
Ciampi
Quirino
Q
Department of Clinical Medicine, Federico II University School of Medicine, Naples, Italy.
Betocchi
Sandro
S
Losi
Maria Angela
MA
Ferro
Adele
A
Cuocolo
Alberto
A
Lombardi
Raffaella
R
Villari
Bruno
B
Chiariello
Massimo
M
D000293:Adolescent; D000328:Adult; D001794:Blood Pressure; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications* / Q000503:physiopathology*; D005080:Exercise Test / Q000009:adverse effects*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000209:etiology* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption