Role of increases in heart rate in determining the occurrence and frequency of myocardial ischemia during daily life in patients with stable coronary artery disease.
J Am Coll Cardiol
; 20(5): 1092-8, 1992 Nov 01.
Article
em En
| MEDLINE
| ID: mdl-1401608
ABSTRACT
OBJECTIVES:
The goal of this study was to investigate the role of increases in heart rate in the development of ischemic episodes recorded during ambulatory electrocardiographic (ECG) monitoring in patients with stable coronary artery disease and to establish the importance of such increases in determining the frequency of ambulatory myocardial ischemia.BACKGROUND:
The factors that determine the occurrence and frequency of episodes of myocardial ischemia that patients with stable coronary artery disease experience during daily life have not been clearly defined. In particular, the role of increases in heart rate in the development of myocardial ischemia is controversial.METHODS:
To address these issues, 54 patients (42 men and 12 women, mean age 60.5 +/- 8 years) with proved coronary artery disease who had > or = 1 mm ST segment depression during exercise testing underwent an exercise treadmill test with use of the National Institutes of Health combined protocol and a 48-h period of ambulatory ECG monitoring. The exercise ischemic threshold was determined as the heart rate at the onset of ST segment depression during exercise testing.RESULTS:
During monitoring, 48 (89%) of the 54 patients had at least one episode of ST segment depression (mean +/- SD 6.6 +/- 5 episodes, range 0 to 22). The majority (320 of 359 or 89%) of ischemic episodes were preceded by an increase in heart rate > or = 10 beats/min; the most significant increase (22.3 +/- 10 beats/min) occurred during the 5-min period before the onset of the episode. An ischemic episode occurred 80% of the times the heart rate reached the exercise ischemic threshold. A strong correlation was observed between the number of times the exercise ischemic threshold was reached during monitoring and both the number and the duration of ischemic episodes (r = 0.90 and 0.71, respectively, p < 0.0001).CONCLUSIONS:
Increases in heart rate that exceed the exercise ischemic threshold are commonly observed before the onset of episodes of ambulatory myocardial ischemia in patients with stable coronary artery disease. Moreover, such increases constitute an important determinant of the frequency of myocardial ischemia during daily life. These findings may explain the variability observed in the number of ischemic episodes and may have important implications for the mechanisms that contribute to myocardial ischemia in daily life and for the clinical evaluation of patients with coronary artery disease.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Atividades Cotidianas
/
Isquemia Miocárdica
/
Doença das Coronárias
/
Frequência Cardíaca
Tipo de estudo:
Guideline
/
Incidence_studies
/
Prognostic_studies
Limite:
Adult
/
Aged
/
Female
/
Humans
/
Male
/
Middle aged
Idioma:
En
Revista:
J Am Coll Cardiol
Ano de publicação:
1992
Tipo de documento:
Article