Narcotics like cocaine and meth increase the heart rate, as they cause a sympathetic surge (adrenaline rush).
It not only causes an increased heart rate but it can cause your coronary arteries (the blood vessels to your heart) to constrict (squeeze), resulting in heart attacks due to not enough blood and oxygen getting to the cardiac tissue.
Additionally, cocaine has been shown to accelerate the process of atherosclerosis (plaque build-up inside arteries) which can lead to heart attacks as well.
In other words, you can make your 20 year old arteries look like those of a 60 year old.
[Read more…] about Why Is Exercise That Increases Heart Rate Considered Good, But Narcotics That Increase Heart Rate Considered Bad?