Striking at the heart of America: Trauma of 9/11 linked to spike in MI

Susan Jeffrey

January 13, 2005

New York, NY - A new analysis using data from the Worcester Heart Attack Study shows a transient rise in the risk for myocardial infarction on the day of and the day after the terrorist attacks in New York and Washington on September 11, 2001, as high as three times the risk seen in previous months or years.

"Our results suggest that the terrorist attacks on September 11 may have resulted in a transitory increase in the number of heart attacks occurring in greater Worcester residents," the authors, led by Dr Robert J Goldberg (University of Massachusetts Medical School, Worcester), conclude.

If the finding is real, they write, "this may have resulted in the occurrence of a considerable number of additional heart attacks nationally in the few days after the events of September 11." Although the play of chance cannot be ruled out, their findings reinforce the need to explore different mechanisms through which acute stress or other triggering factors might precipitate MI, they conclude.

The new report appears in the January 15, 2005 issue of the American Journal of Cardiology.[1]

Tragic events

The Worcester Heart Attack Study is an ongoing NIH-supported project examining changes over time in the incidence and case-fatality rates of acute MI in residents of Worcester, MA. The Worcester metropolitan area is less than 200 miles from New York City, and both planes that crashed into the towers of the World Trade Center originated from Boston, MA, the researchers note.

Although the study includes data back to 1975, they limited their comparison for this report to the decade before the attacks. They compared data from 1991-1999, the usual or endemic magnitude of MI, with the possible "epidemic" effects of the attacks on September 11. Medical records of all patients with a discharge diagnosis of MI from 11 hospitals in the area were abstracted.

In 2001, the average number of cases daily was 3.4 in the nine-month period ending on September 10. On September 11, there were seven cases, nine on September 12, and 13 additional cases during the remainder of the week. In the month after September 11, the daily mean again fell to 4.1 cases and 3.5 in the three-month period thereafter.

In contrast, the average number of cases hospitalized daily for MI in the period 1991-1999 was 2.7, with an average of 1.8 cases on September 11 and 2.6 cases on September 12 over that period.

Compared with the control period, the risk of MI was significantly increased on September 11 and on September 12, 2001. The increase appeared transient, with no increase in events evident as soon as the week afterward.

Risk of MI on September 11, 2001 and time points afterward compared with previous unexposed period

Time point Odds ratio 95% CI
September 11, 2001 3.04 1.13-8.17
September 12, 2001 2.85 1.49-5.45
One week after Sept 11 1.23 0.81-1.87
One month after Sept 11 1.20 0.97-1.48
Three months after Sept 11 1.05 0.91-1.22

A simple count of cases on consecutive days in the control period showed that on no occasion before the 9/11 attacks were there 16 cases over a two-day period, as was seen on Sept 11-12, 2001.

"That to me suggests that it's probably a real finding, when you consider the sheer number of paired days we looked at," Goldberg told heart wire . They hope to look next at the effect of the attacks on out-of-hospital deaths from heart disease, "which, subject to all the limitations of death certificates and so on, would really complete the whole story," he said.

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