# 5545
STEMI on EKG- credit Wikidoc.org
Admittedly, there is no good time to have a heart attack, but new research is casting light on the fact that the time of day when a person has a myocardial infarction may affect its severity.
Last November (see A Different Kind Of Holiday Tradition) I wrote about the seasonality of heart attacks (they spike as much as 33% during the holiday season - between Thanksgiving and mid-January).
The reasons for this are not entirely clear, but may be due to a variety of factors:
Colder temperatures, increased respiratory infections, over indulgence in food and alcohol, diminished activity levels, forgetting to take prescription medicines, and the combined stressors of shopping, running up debt for gifts, traveling, meal preparation, and/or the stress that comes from dysfunctional family gatherings.
But as any paramedic will tell you, mornings are prime time for cardiac calls anytime of the year.
In fact studies have shown that people are 40% more likely to experience a heart attack between 4am-10am than any other time of the day (cite).
But now there is growing evidence that myocardial infarctions that occur in the morning may cause more heart muscle damage than those that occur during other times of the day as well.
First the study which appears in the BMJ Heart Journal, then some discussion.
Heart doi:10.1136/hrt.2010.212621
Circadian variations of infarct size in acute myocardial infarction
Aida Suárez-Barrientos, Pedro López-Romero, David Vivas1,Francisco Castro-Ferreira, Ivan Núñez-Gil, Eduardo Franco, Borja Ruiz-Mateos, Juan Carlos García-Rubira, Antonio Fernández-Ortiz, Carlos Macaya, Borja Ibanez
Abstract
Background The circadian clock influences a number of cardiovascular (patho)physiological processes including the incidence of acute myocardial infarction. A circadian variation in infarct size has recently been shown in rodents, but there is no clinical evidence of this finding.
Objective To determine the impact of time-of-day onset of ST segment elevation myocardial infarction (STEMI) on infarct size.
<SNIP>
Conclusions Significant circadian oscillations in infarct size were found in patients according to time-of-day of STEMI onset. The infarct size was found to be significantly larger with STEMI onset in the dark-to-light transition period (6:00–noon). If confirmed, these results may have a significant impact on the interpretation of clinical trials of cardioprotective strategies in STEMI.
Essentially, researchers looked at cardiac enzyme levels of more than 800 patients in Madrid, Spain who were having an STEMI (ST segment elevation myocardial infarction).
STEMIs are serious heart attacks that affect a large portion of cardiac muscle and show up on EKGs (ST segment elevation) and produce a spike in cardiac enzymes (indicative of muscle damage).
The peak levels of cardiac enzymes released - Creatine kinase (CK) and troponin-I (TnI) – provide a good indication of the amount of coronary muscle damage.
By comparing peak enzyme levels in patients with their time of coronary onset, researchers were able to determine what time of day the most severe heart attacks occurred.
And the results showed that heart attacks that began during the dark-to-light transition period (6:00–noon), showed roughly 20% more tissue death, compared with heart attacks with onsets between 6pm and midnight.
The current theory as to why this might be is that the body’s circadian rhythm influences the production of cardio-protective proteins called salvage kinases, which are released in greater quantities later in the day.
The hope is that this kind of research will eventually lead to new therapies and treatments which might reduce the amount of muscle damage during heart attacks.
For now, the best defense is to remember to take your prescribed medications and to pay attention to the signs and symptoms of a heart attack, and not delay calling 9-1-1.
From the CDC’s Heart Attack Information page:
Symptoms of a Heart Attack
The five major symptoms of a heart attack are—
- Pain or discomfort in the jaw, neck, or back.
- Feeling weak, light-headed, or faint.
- Chest pain or discomfort.
- Pain or discomfort in arms or shoulder.
- Shortness of breath.
If you think that you or someone you know is having a heart attack, you should call 9–1–1 immediately.
And while you are thinking about gifts for your family and friends this year, one gift you can give them is to take a CPR course – so you can help save their life if their heart should stop due to a heart attack, electrocution, anaphylactic reaction or drowning.
Compression-only CPR is now the standard for laypeople, and is easier to do than the old way.
While it won’t take the place of an actual class, you can watch how it is done on in this brief instructional video from the American Heart Association.
A class only takes a few hours, and it could end up helping you save the life of someone you love.
To find a local CPR course contact your local chapter of the American Red Cross, the American Heart Association, or (usually) your local fire department or EMS can steer you to a class.
