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Heart attack timing crucial

People who suffer heart attacks in the morning are at a higher risk of suffering more long-term damage, according to a study.

A team of Spanish researchers found that patients who had an attack between 6am and noon suffered 20% more damage.

They linked the results to circadian rhythms, the 24-hour body clock processes that influence many biological functions.

Heart attacks were known to occur more often when a person awakes from sleep, but it was unclear to what extent timing affected their severity.

Analysing data on 811 patients admitted to the Hospital Clinico San Carlos in Madrid, the researchers measured the amount of dead heart tissue left by attacks.

The size of the dead area was calculated by looking at levels of enzymes in the patients.

Timing of heart attacks was divided into four six-hour periods running in phase with 24-hour circadian rhythms.

Patients with the largest infarct size were those whose heart attacks occurred in the dark-to-light transition period between 6am and noon.

In total, 269 patients had their heart attack during the morning danger period. Another 240 suffered attacks between noon and 6pm, 161 between 6pm and midnight, and 141 between midnight and 6am.

The findings have been published online in the journal Heart.

Copyright © Press Association 2011


Your comments (terms and conditions apply):

"It would be interesting to know if there is a difference in the number of infarct victims who survive at different times of day in the same catchment area and also if there are influences of the healthcare system - rota changes etc. The idea of a 'Dark to Light Transition' lasting six hours until mid-day in Spain seems a little 'broad strokes' too" - Name and address supplied