With the recent record-breaking heat, doctors are reminding heart patients that high temperatures can take a toll on their health and even cause a cardiac crisis.

They say the heat can be uncomfortable for people with existing heart disease and dangerous – especially if they have multiple medical problems such as high blood pressure.

Doctors say the heat can strain a person's heart and put them at risk of a heart attack or an irregular heartbeat, also known as an arrhythmia. The heat can also exacerbate heart failure.

There are three factors that can lead to people suffering from heart issues during the summer.

Your heart has to work harder to pump blood to the skin to cool you off.

People become dehydrated and sweat more in the summer. Doctors say sweating leads to loss of fluids, which can thicken the blood and make it harder on the heart. That can increase the risk of blood clots.

The heat can impact a person's electrolytes – the natural chemicals found in body fluid like potassium and sodium that are needed to maintain fluid balance, regular nerve and muscle function and contribute to a person's overall health. An electrolyte imbalance can lead to arrhythmias.

Doctors suggest people with heart issues avoid the outdoors once the temperatures increase.

New data shows that there are 90% fewer deaths from heart attacks in the U.S. since 1970. The findings, published in the in the Journal of the American Heart Association, are based on 50 years of statistics. The study's lead author says advances in diagnosis and treatment have helped people survive cardiac events that were once considered fatal.