Freezing
outdoor temperatures is associated with an elevated risk for heart attack but
weather conditions independent of the cold can also be triggers, suggests a
cohort study from across Sweden.
For STEMI and
NSTEMI combined, lower daily air temperature, lower atmospheric air pressure,
higher wind velocity, and shorter duration of sunshine appeared to be
independent triggers among the 274,029 patients in
the SWEDEHEART registry cohort.
The strongest
association was observed for air temperature, with a higher incidence of MI on
days with air temperatures less than 0°C, with rates of MI declining when
temperatures rose to greater than 3°C to 4°C," (October 24
in JAMA Cardiology)
In the
analysis, a one-standard-deviation rise in air temperature that is by 7.4°C,
corresponded to a 2.8% reduction in risk for MI.
Pollution and Heart Attack
Every 10 mcg/m3
increase in pollution there is significant increases in the risk of
a cardiovascular event, (hazard ratio 1.24), death from heart
disease (HR 1.76), and stroke (HR 1.35). (N Engl J Med 2007;
356:447). PM2.5 concentration is associated with the risk of cardiac death
(relative risk 1.2). (N Engl J Med 2009; 360:1085).
CO, NO2, SO2
and PM 2.5 are also linked to an increased risk of acute heart attack with risk
ranging from 1 to 5 percent (JAMA 2012; 307:713).
PM < 10 increases the risk by raising the
blood pressure through an increase in sympathetic tone (Circulation
2002; 105:1534), transient increases in plasma viscosity and impaired
endothelial dysfunction (Circulation 2002; 106:933.) and the initiation of
atherosclerosis (Circulation 2010; 121:2755, J Am Coll Cardiol 2010;
56:1803)
Dr KK Aggarwal
Padma Shri Awardee
President Elect Confederation of Medical
Associations in Asia and Oceania (CMAAO)
Group Editor-in-Chief IJCP Publications
President Heart Care Foundation of India
Immediate Past National President IMA
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