Anyone who has ever lived in New York City or visited it can attest to the high-octane existence of its inhabitants. Twenty-four-hour activity, cabbies screaming at each other, and bodies packed onto the subways. Even visitors don’t seem immune from the frenzy. A tourist strolling down 42nd Street, for instance, stuck his hand in his back pocket, only to encounter another hand already there, reaching for his wallet.

Thus, it will probably come as no surprise that New Yorkers are dying from heart attacks in dramatic numbers. But it may come as a jolt that visitors to the " Big Apple" are also dying from heart attacks in larger numbers than would be expected. In other words, it looks as if the " Big Apple" may be toxic to your health, even in limited doses, a study reported in the November/December Psychosomatic Medicine implies.

In 1994, some researchers reported the first tantalizing suggestion that New Yorkers might be at especially high risk of fatal heart attacks due to ischemic heart disease. So Nicholas Christenfeld, Ph.D., a psychologist with the University of California at San Diego, and his colleagues decided to see whether they could confirm this finding, and if so, get a better idea of why New Yorkers might be at so much greater a risk. In brief, they attempted to answer these questions: Do New Yorkers die more from heart attacks provoked by ischemic heart disease than one would expect, do visitors to New York City die more from heart attacks than one would anticipate, and do New Yorkers who succumb away from New York City die more from such heart attacks than one would reckon?

They used as their research material U.S. death certificates from 1985 to 1994, since 1994 was the latest year for which computerized death certificates were available. These certificates list cause and location of death and location of the decedent’s residence. The types of analyses they performed on the certificates were proportional mortality analyses (PMRs). The PMR allows one to assess the overrepresentation of a disease in a population whose precise size is not known, but for which all deaths are recorded. Thus, in their first analysis, they compared the observed number of ischemic heart disease–triggered deaths for New York City residents who died in New York City with the expected number of such deaths, which was calculated from the proportion of iscehmic heart disease deaths in the rest of the United States among those who died in their county of residence.

In their second analysis, they compared the observed number of ischemic heart disease deaths for visitors who died in New York City with the expected number, which was calculated from the proportion of such deaths in the rest of the U.S. population among those who died outside their county of residence. And for the third analysis, they compared the observed number of deaths caused by ischemic heart disease among New York City residents dying outside the city with the expected number, which was calculated from the proportion of these deaths of New York City residents who died in the city. And in each analysis, adjustments were made for differences in age, race, sex, and education.

The researchers found, on the basis of these analyses, that a lot more New Yorkers were dying each year from ischemic heart disease than expected—8,074 more than anticipated, to be precise, or 155 percent of the expected number. The investigators also found that more visitors to New York City were dying from ischemic heart disease each year than anticipated—262 more, or 134 percent of the expected proportion. At the same time, the scientists discovered that 310 fewer New Yorkers were succumbing from heart attacks away from New York than was expected, or only 80 percent of the predicted number. All these results were statistically significant, implying that they were not due to chance.

Thus, there seems to be something in New York City itself, not in New Yorkers, that leads to a fatal heart attack, the researchers concluded, because if it were something in New Yorkers themselves, then visitors would not be affected, and just as many New Yorkers would be dying away from New York City from heart attacks as if they had stayed home.

But what is it in New York City that might predispose one to a heart attack? Although air quality has been linked to heart disease, New York City does not have unusually high levels of air pollution, the researchers point out. However, both chronic stress and acute stress have been linked with ischemic heart disease, and as few will contest, New York City can be a very stressful place. Thus, the investigators believe, it could well be the stress of the Big Apple that can do the heart in. In native New Yorkers, they hypothesize, chronic stress could lead to hardening of the arteries, reduced blood flow to the heart, and then a heart attack, whereas in visitors to New York, the stress of the city could trigger a fatal heart attack in those already having ischemic heart disease.

In any event, the scientists reported, " If stress is in part responsible for our findings, the data do not indicate whether it is the fast pace, late nights, excitement, fear, or some other aspect of New York City that is critical."

Whatever is toxic about America’s largest city, though, doesn’t seem to exist in America’s other metropolises, because Christenfeld and his team ran similar anlyses on the 10 largest cities after New York—Los Angeles, Chicago, Houston, Philadelphia, San Diego, Dallas, Phoenix, Detroit, San Antonio, and San Jose—and found very little elevation in ischemic heart disease deaths among residents or visitors beyond what was statistically expected. In fact, when residents of these cities left home, they tended to die somewhat more from ischemic heart disease, not less.

In an accompanying editorial, George A. Kaplan, Ph.D., of the department of epidemiology at the University of Michigan at Ann Arbor, pointed out that PMRs, the types of analyses that Christenfeld and his colleagues used, have their weaknesses. Nonetheless, he conceded that the " New York City effect" on the heart might be real and concludes that " there seems to be considerable accumulating evidence that where one lives does influence one’s health." — J.A.T.