Related Experiment Videos
Patterns and behavior of transient myocardial ischemia in stable coronary disease are the same in both men and women:
1Cardiology Branch of Biostatistics Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
Insights
Women with coronary artery disease show similar daily patterns of ischemic activity and heart rate variations as men. These findings highlight the importance of myocardial oxygen demand in ischemia for both genders.
Area of Science:
- Cardiology
- Circadian Biology
- Gender Differences in Health
Background:
- Circadian variations influence ischemic activity, myocardial infarction, and sudden cardiac death in coronary artery disease (CAD).
- Previous ischemia studies have largely focused on male populations, limiting understanding of gender-specific patterns.
Purpose of the Study:
- To compare circadian variations in transient ischemic activity, mean heart rate, and ischemic threshold between women and men with CAD.
- To investigate potential gender differences in the pathophysiological mechanisms of ischemia.
Main Methods:
- Ambulatory ST segment monitoring for at least 48 hours in 31 women and 45 men with CAD.
- Analysis of circadian variations in ischemic activity, heart rate, and heart rate at the onset of ischemia (ischemic threshold).
Main Results:
- Both women and men exhibited significant circadian variations in ischemic activity, with a nocturnal trough and a peak in the early afternoon.
- Mean heart rate and the ischemic threshold showed similar circadian patterns in both genders, with no significant differences.
- Heart rate consistently increased before ischemic episodes, with no gender-specific differences in this pre-ischemic heart rate elevation.
Conclusions:
- Women with CAD demonstrate ischemic activity patterns and underlying mechanisms comparable to men.
- Increased myocardial oxygen demand, reflected by heart rate surges before ischemia, plays a crucial role in both genders.
- A lower ischemic threshold during nighttime, coinciding with lower blood pressure, suggests a circadian influence on coronary vascular tone.
Objectives:
This study sought to compare the circadian variations in transient ischemic activity, mean heart rate and ischemic threshold between women and men with coronary artery disease.
Background:
There is a circadian variation in ischemic activity, onset of myocardial infarction and sudden cardiac death in patients with coronary artery disease, but studies assessing ischemia have incorporated predominantly male subjects.
Methods:
Thirty-one women and 45 men underwent at least 48 h of ambulatory ST segment monitoring.
Results:
There was a similar and significant circadian variation in ischemic activity in both women and men (p < 0.0001 and p < 0.0001, respectively), with a trough at night, a surge in the morning and a peak between 1 and 2 PM, corresponding to a similar circadian variation in mean hourly heart rate (p < 0.0001) that was not different between men and women (p = 0.28, power to detect a shift 99.9%). Mean heart rate at onset of ischemia (ischemic threshold) had similar variability in women and men (p = 0.96), and harmonic regression analysis confirmed a significant circadian variation (p < 0.0001), with a trough at night and a peak during activity hours. Heart rate increased significantly in the 5 min before ischemia throughout the 24 h (p < 0.0001), with no gender differences in the pattern of preonset to onset heart rate changes over time (p = 0.52); the smallest differences were recorded in the middle of the night. The majority of ischemic episodes (80%) had a heart rate increase > 5 beats/min in the 5 min before ischemia, but there were no gender differences.
Conclusions:
Women with coronary artery disease have a pattern of ischemic activity and underlying pathophysiologic mechanisms very similar to men. The importance of increase in myocardial oxygen demand in the genesis of ischemia in both men and women is reflected by similar magnitude of heart rate increases before ischemia. The lower ischemic threshold during the nocturnal hours, when blood pressure is also lower, is consistent with a circadian variation in underlying coronary vascular tone.