Low temperature, low pressure and strong wind related to the risk of infarction

A range of weather conditions was linked to an increased risk of myocardial infarction (MI), a large prospective Swedish population-based study.

The presence of MI varied according to air temperature, atmospheric pressure, wind speed, and sunshine hours on a given day. The most obvious relationship was air temperature, in which an increase of 1 standard deviation (SD) (7.4 ° C or 13.32 ° F) was related to a 2.8% decrease. the risk of IM (unadjusted incidence rate ratio of 0.972, 95% CI 0.967 -0.977, P<0.001), said David Erlinge, MD, Ph.D., of Lund University in Sweden, and his colleagues from JAMA Cardiology.

The researchers noted that previous reports had highlighted an association between colder climates and the risk of MI, but that these documents relied on proxy variables "as MI indicators, and many studies have focused solely on the temperature of the air and snow, and other meteorological parameters have largely studied. "

The current study aimed to evaluate all meteorological parameters and the incidence of MI, "by combining clinical data with meteorological variables from meteorological stations collected near the coronary care units (CCUs)", so that authors can "examine the associations of the main meteorological parameters and the risk of MI."

These findings are "consistent with previous studies showing that heart attacks seem to occur more frequently in more extreme weather, especially in cold winter weather," said Kim Eagle, MD, of the University of Michigan at Ann. Arbor, who has not been involved in the study.

"We believe that the coronary arteries may have less reserve of vasodilators in the cold or, for diseased segments, may even constrict in the cold, which may be associated with a rupture of the coronary artery plaque "said Eagle. MedPage today.

The researchers evaluated 274,029 patients with MI, aged on average 71.2 years in Sweden. The Erlinge group collected weather data and merged it with each MI according to the date the symptom first manifested and the CCU.

For atmospheric pressure (kilopascal or kPa) and duration of sunshine, an increase in 1-SD of each was associated with a reduced risk of myocardial infarction:

• Atmospheric pressure 10.9 kPa: adjusted TRI 0.987 (95% CI 0.981-0.993, P<0.001)
• Sunshine duration 4.2 hours: IR 0.987 unadjusted (95% CI 0.983-0.992, P<0.001)

An increase in 1-SD of wind speed (1.9 m / s) was associated with an increased risk of MI (adjusted IRR 1.012, 95% CI 1.005-1.018, P<0.01).

Even within a relatively localized geographic area, these changes are noticeable, said Robert Bonow, MD, of Northwestern Memorial Hospital in Chicago. However, these findings "may or may not be generalizable to a person living in Italy," said Bonow.

Another limitation of the study is that it is not very exploitable; It is difficult to make interventions based on these findings, noted Mr. Bonow, but he added that it was important that patients with heart disease and their caregivers know that there are times of the year when the risks are greater.

Clinicians prefer patients who exercise in warm weather and generally advise patients with known coronary heart disease to avoid intense exercise in cold weather, noted Eagle. "If they sand or blow the snow, [we] prefer wearing a scarf over the nose and mouth to warm the air before it hits the lungs. Patients should absolutely warm up and calm down if they are exercising in cold weather. "

2018-10-24T17: 00: 00-0400