People with weak hearts should avoid riding roller-coasters as they could be risking their lives, cardiologists say.
Healthy people should not be affected by a ride, researchers say
The thrill of the ride can spark irregular beats in those with heart disease and put them at risk of a heart attack, a study argues.
Emotional stress seems to be a strong contributing factor, said German researchers who monitored 55 people who volunteered to take a ride.
The findings were presented at an American Heart Association meeting.
The researchers studied 37 men and 18 women who volunteered to take a roller-coaster ride while having their heart and blood pressure monitored.
The ride involved a two-minute journey, starting with a slow ascent to 62 metres above the ground, followed by a free fall, big changes in gravity and a maximum speed of 75 miles per hour.
Even though all the volunteers were healthy, many experienced dramatically increased heart rates during the ride.
Some experienced irregular heart beats and one experienced a heart rhythm disorder called atrial fibrillation - a rapid chaotic electrical activity in the upper chambers of the heart. This corrected itself.
Although such changes should not be a problem for those with healthy hearts, they could be dangerous in those with cardiovascular disease, believe the study authors.
Dr Jurgen Kuschyk, from the University Hospital in Mannheim, which is affiliated to the University of Heidelberg, said: "Individuals who have suffered a heart attack, have heart disease or irregular heart rhythms should not ride a roller-coaster.
"The rising heart rate in riders with pre-existing heart disease could result in heart attack, irregular heart rhythms and possibly sudden cardiac death."
June Davison, medical spokeswoman for the British Heart Foundation, said: "For the majority of people, fairground rides are a fun part of a trip to a theme park and not something to be unduly concerned about.
"However, anyone with an underlying heart condition or at high risk of heart disease should seek medical advice from their GP or specialist about whether they're fit enough to go on certain rides and should always take notice of cautionary signs.
"In the very rare cases where someone has an underlying, undetected heart condition...they may encounter problems."