Although the effects of MDMA on the heart and blood vessels are normally an insignificant increase in blood pressure and heart rate, there have been reports of serious problems due to these effects. Hypertension (abnormally high blood pressure) can lead to organ damage such as acute renal failure (Woodrow et al. 1995). Another cardiovascular effect is abnormal heart rhythms. Although it is rare, this can become bad enough to cause heart fibrillations which can lead to death.
Impaired attention and concentration