Severity of heart attack is dependent on the time of day

November 21, 2011

The size of a heart attack and subsequent left-ventricular function are significantly different based on the time of day onset of ischemia, according to a first of its kind study in humans, published online Nov. 17 in Circulation Research. The greatest amount of injury to the heart occurs when individuals have a heart attack between 1:00am and 5:00am.

In previous research, the infarct size in rodents following ischemia and reperfusion exhibited a circadian dependence on the time of coronary occlusion. A circadian rhythm is an endogenously driven, roughly 24-hour cycle in biochemical, physiological or behavioral processes. Previously, it was unknown if a similar circadian dependence of infarct size occurs in humans.

"We were trying to ascertain whether the time of day of when a heart attack occurs influences the amount of damage that the heart sustains, or was this just a phenomenon exhibited in rodents," said the study's senior author Jay H. Traverse, MD, a cardiologist at the Minneapolis Heart Institute at Abbott Northwestern Hospital in Minneapolis and physician researcher with Minneapolis Heart Institute Foundation.

A of 1,031 patients in the Level 1 acute MI database with an , or ST-elevation (STEMI), referred for primary (PCI) with known ischemic times between one and six hours, identified 165 patients with their first heart attack who had occluded arteries on presentation without evidence of pre-infarction angina or collateral blood flow.

All 165 patients had well-defined ischemic times and the data were supported by a subgroup with cardiac MRI measurements of infarct size, or size of heart attack, and area-at-risk.

The researchers observed that the extent of infarct size was significantly associated with time of day onset of infarction. The greatest myocardial injury occurred at a 1:00am onset of ischemia and 5:00am onset of with the peak injury being 82 percent higher than that recorded at lowest time of injury.

What are the implications of these findings? "It is important to understand that the heart's ability to protect itself against more severe damage varies over a 24-hour cycle. Identifying those protective changes may be particularly relevant for pharmaceutical manufacturers that are seeking to develop cardioprotective drugs," Traverse explained.

Explore further: Heart attacks are more serious if they occur at certain times of the day

Related Stories

Heart attacks are more serious if they occur at certain times of the day

April 28, 2011
People who have a heart attack are likely to be more seriously affected if the attack happens in the morning, reveals research published ahead of print in Heart journal.

Study examines outcomes of erythropoietin use for heart attack patients undergoing PCI

May 10, 2011
Intravenous administration of epoetin alfa, a product that stimulates red blood cell production, to patients with heart attack who were undergoing percutaneous coronary intervention (PCI; procedures such as balloon angioplasty ...

Study shows man-made fat may limit damage to heart attack victims

August 5, 2011
A man-made fat called Intralipid, which is currently used as a component of intravenous nutrition and to treat rare overdoses of local anesthetics, may also offer protection for patients suffering from heart attacks.

Study shows balloon pump use prior to angioplasty does not reduce heart muscle damage

August 30, 2011
Inserting intra-aortic balloon pumps prior to angioplasty in patients with acute myocardial infarction (AMI) does not reduce the scope of heart muscle damage, a condition referred to as infarct size, according to a new study ...

Recommended for you

Could aggressive blood pressure treatments lead to kidney damage?

July 18, 2017
Aggressive combination treatments for high blood pressure that are intended to protect the kidneys may actually be damaging the organs, new research from the University of Virginia School of Medicine suggests.

Quantifying effectiveness of treatment for irregular heartbeat

July 17, 2017
In a small proof-of-concept study, researchers at Johns Hopkins report a complex mathematical method to measure electrical communications within the heart can successfully predict the effectiveness of catheter ablation, the ...

Concerns over side effects of statins stopping stroke survivors taking medication

July 17, 2017
Negative media coverage of the side effects associated with taking statins, and patients' own experiences of taking the drugs, are among the reasons cited by stroke survivors and their carers for stopping taking potentially ...

Study discovers anticoagulant drugs are being prescribed against safety advice

July 17, 2017
A study by researchers at the University of Birmingham has shown that GPs are prescribing anticoagulants to patients with an irregular heartbeat against official safety advice.

Protein may protect against heart attack

July 14, 2017
DDK3 could be used as a new therapy to stop the build-up of fatty material inside the arteries

Heart study finds faulty link between biomarkers and clinical outcomes

July 14, 2017
Surrogate endpoints (biomarkers), which are routinely used in clinical research to test new drugs, should not be trusted as the ultimate measure to approve new health interventions in cardiovascular medicine, according to ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.