Heart attack between 1am to 5am causes greatest injury

 Heart attack between 1am to 5am causes greatest injuryWashington, Nov 22 : A new study has found that severity of heart attack is dependent on the time of day the attack occurs.

The researchers said the size of a heart attack and subsequent left-ventricular function are significantly different based on the time of onset of ischemia.

The greatest amount of injury to the heart occurs when individuals have a heart attack between 1:00am and 5:00am.

"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.

A retrospective analysis of 1,031 patients in the Level 1 acute MI database with an acute heart attack, or ST-elevation myocardial infarction (STEMI), referred for primary percutaneous coronary intervention (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.

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 reperfusion with the peak injury being 82 percent higher than that recorded at lowest time of injury.