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Seismic scale of earthquakes, aftershocks tied to frequency of acute MI
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The increase in acute MI events after a massive earthquake in Japan varied depending on the seismic scale of the earthquake and each aftershock, according to the results of a population-based study.
Previous research had suggested a relationship between large earthquakes and ACS events, but had yielded conflicting results, according to the study background. The researchers aimed to clarify the influence of the magnitude-9.0 earthquake that hit northeast Japan in 2011 and its aftershocks on the risk for acute MI, including sudden cardiac death.
They analyzed acute MI events in the northeastern region of Japan’s Iwate prefecture, comparing the incidence of acute MI in the area from 4 weeks before to 8 weeks after the earthquake with the incidence during the same period in 2009 and 2010.
Fumitaka Tanaka, MD, and colleagues found that compared with the corresponding period in 2009 and 2010, the RR for acute MI in the area increased twofold during the 4-week period after the earthquake (2009, 20.7 per 100,000 people; 2010, 16.1 per 100,000; 2011, 35.2 per 100,000; RR = 2.03; 95% CI, 1.55-2.66).
Tanaka, from the department of internal medicine at Iwate Medical University, Morioka, Japan, and colleagues determined that acute MI was positively correlated with seismic scale (r = 0.75; P < .01). Specifically, the incidence of acute MI peaked during the first week after the disaster (RR = 2.77; 95% CI, 1.73-4.43), dropped to levels consistent with previous years in the second week, and increased again in the third week (RR = 1.84; 95% CI, 1.05-3.24) and fourth week (RR = 2; 95% CI, 1.13-3.55), related closely to the weekly maximum seismic intensity. From the fifth week onward, acute MI incidence did not differ from that observed during previous years.
“The relationship found in this analysis between weekly seismic activity and cardiac events that occurred in the same week will be relatively novel,” Tanaka and colleagues wrote. “This suggests a rapid causal effect in seismic activity, the associated stress, and cardiac events. The aftershocks, most of which caused little environmental damage, could apparently also cause significant psychological distress.”
They suggested three measures for risk prevention: maintaining or restoring medical supports as quickly as possible; increasing provision of defibrillators and rapid cardiac resuscitation capability to reduce incidence of sudden cardiac death; and avoidance or modification of physical and emotional distress induced by disaster. An example of the latter is adding beta-blockers to the medication regimens of those at high CV risk when aftershocks are predicted, they wrote. – by Erik Swain
Disclosure: The study was supported in part by the Takeda Science Foundation. The researchers report no relevant financial disclosures.
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