Deaths from heart disease and stroke likely climb in Mass. during heat waves

The current three-day heat wave baking much of Massachusetts will likely cause six to eight more deaths in the state from heart attacks, strokes and cardiac arrest than would be expected in that same timeframe without excessive heat. That prediction is based on research and analysis from Dr. Dhruv Kazi, director of cardiac critical care at Beth Israel Deaconess Medical Center.

With major cities like Boston experiencing up to six heat waves a year on average, the toll from heat-related cardiac deaths climbs.

“It’s the equivalent of a busload of people careening into a ravine,” Kazi said, of these excess heat-related cardiac deaths. “That would almost certainly make headlines and yet this incremental cardiovascular risk due to heat, we’ve kind of come to accept as normal.”

Heat stresses the heart, making the organ work harder to pump blood through the body and cool the skin. Dehydration and cellular changes can thicken blood and reduce the flow, making clots and a heart attack or stroke more likely. Shifts in the body’s electrolyte balance can trigger abnormal heart rhythms in some patients.

During a heat wave, Kazi said warm nights are a problem in addition to unusually hot days because they don’t allow the body to cool down.

“They amplify the physiologic effects of extreme heat on the body,” said Kazi, who is also associate director at the Smith Center for Outcomes Research in Cardiology at Beth Israel.

That nighttime effect explains why some doctors say to put an AC window unit, if you only have one, in the bedroom to make sure you get a good night’s sleep.

During the day, many municipalities have a library or other cooling center where residents can find relief. But Kazi and others worry about patients with heart disease who have to work outdoors or in un-airconditioned buildings.

“The outcomes of heat waves as with the outcomes of climate change affect us all but they do not affect us all equally,” he said.

Research shows the number of nonfatal heart attacks and strokes also rises during a heat wave. But it’s not clear how often cardiologists routinely discuss these risks with their patients.

Chrissy Gaffney of Worcester has largely figured out how to cope on her own. She was born with a heart defect and manages a diagnosis of acute heart failure.

This week’s heat wave has triggered many of the symptoms Gaffney has come to associate with temperatures in the 90s. She’s short of breath, nauseous, sweats excessively and gets headaches. Gaffney adjusts her schedule as a merchandise associate with the WooSox baseball team so she can work days in the air-conditioned team store. She stays out of the heat as much as possible.

Gaffney, who volunteers with the American Heart Association, says she’s not surprised by the predictions for excess cardiac-related deaths during a heat wave.

“If people are unaware of how to take precautions or know when to seek medical help, I can see how that could happen,” she said.

Heat is rarely listed as an official cause of death, but Kazi said this insidious threat must still be taken seriously, especially in the Northeast and other parts of the country where residents are less prepared and more vulnerable. He said it’s time to consider mandating that landlords provide air-conditioning in line with required heating.

“We know how to protect people from the effects of heat,” he said. “We have to do it.”