Blood leaks back into the chambers rather than flowing forward through the heart or into an artery. In the United States, backflow most often is due to prolapse. Prolapse is when the flaps of the valve flop or bulge back into an upper heart chamber during a heartbeat. Prolapse mainly affects the mitral valve.
NSTEMI is a shorthand medical term for non-ST segment elevation myocardial infarction. It is one type of myocardial infarction also called heart attack.
The main difference between UAP and NSTEMI is that in the setting of NSTEMI, macro or microvascular coronary flow is reduced enough to produce detectable myocardial necrosis. Using troponin assays, about 30% of patients who were once classified as having unstable angina are now classified as NSTEMI.