Q. Atrial Fibrillation or Flutter?

Transient atrial fibrillation or flutter is seen frequently and can be associated with CAD, rheumatic heart disease, thyrotoxicosis, or myocarditis. It is also seen in people of all ages who have no other abnormalities. Upon testing a subject with atrial fibrillation or further, the ventricular response tends to accelerate very rapidly, probably due to inadequate left ventricular filling resulting in a decreased stroke volume. The ST-segment changes associated with ischaemia are similar to those observed with a sinus rhythm and may be seen in rheumatic heart disease and other cardiac abnormalities. In these cases, the ST-segment depression may indicate left ventricular dysfunction due to primary muscle changes rather than coexisting CAD. In addition the very short diastolic intervals may produce subendocardial ischaemia because of inadequate perfusion time in the face of an otherwise normal ventricular function. When atrial fibrillation or flutter is initiated by exercise, it does not necessarily implicate CAD as the underlying cause, although this is often the primary factor in older subjects.