Korean Circ J.  1990 Sep;20(3):283-289. 10.4070/kcj.1990.20.3.283.

Painful and Silent Myocardial Ischemia during Daily Activity in Stable Angina Pectoris

• Oh DJ
• Seo HS
• Choi SJ
• Choi IS
• Ro YM

• KMID: 1938091
• DOI: http://doi.org/10.4070/kcj.1990.20.3.283

Abstract

To investigate frequency of painful and/or silent myocardial ischemia(SMI) determined by ECG ST-segment depression(more than 1.0mm depression for 0.08 second after J point over 60 seconds) during unrestricted daily activities, 24-hour dynamic ECG was performed in 19 patients(11 males, 8 females) with chronic stable angina pectoris, aged 57.4 years(44 to 73 years). During 456 hours of recording, there were 154 episodes of SMI. Of these, 139 episodes(90.3%) were silent and 15 episodes(9.7%) accompaned chest pain. The higher incidence of SMI than previously published data is probably influenced by 1 patient who disclosed 56 episodes (excluding this, SMI 84.7%). Sixty one percent of episodes of SMI occurred during light activities such as slow walk, hand labor, eating or at rest(sitting at ease), smoking and sleep, and 39% during more strenuous activites such as walk, climbing stairs and physical exercise. In contrast, most of the painful myocardial ischemia(PMI) developed during climbing stairs, walk and physical exercise. Heart rate during episodes of SMI varied ranging from 85.2+/-13.7/min at rest to 115.5+/-19.2/ min druing climbing stairs. Mean ST-segment depressions during episodes of SMI and PMI were 2.0(1.0-4.0)mm and 2.6(1.2-7.0)mm, respectively, in 6 patients who disclosed both SMI and PMI on 24-hour ECG recordings. However, frequency of ischemic episodes was higher(9.0 vs 2.5/day) and duration was longer(13.8min vs 3.0min) in SMI. These findings indicate that transient SMI in patients with chronic stable angina pectoris occurs more frequently than painful myocardial ischemia. In addition, SMI develops during activities that increase heart rate(increased O2 demand) as well as during activites that do not increase heart rate(decreased O2 supply). Therefore, both O2 demand and supply mechanisms may be involved in the pathogenesis of transient SMI in Patients with chronic stable angina pectoris.

MeSH Terms

Angina, Stable*
Chest Pain
Depression
Eating
Electrocardiography
Exercise
Hand
Heart
Heart Rate
Humans
Incidence
Male
Myocardial Ischemia*
Smoke
Smoking
Smoke