While atrial flutter can sometimes go unnoticed, its onset is often marked by characteristic sensations of regular palpitations. Such sensations usually last until the episode resolves, or until the heart rate is controlled.
Atrial flutter is usually well tolerated initially (a high heart rate is for most people just a normal response to exercise), however, people with other underlying heart disease or poor exercise tolerance may rapidly develop symptoms, which can include shortness of breath, chest pains, lightheadedness or dizziness, nausea and, in some patients, nervousness and feelings of impending doom.
Prolonged fast flutter may lead to decompensation with loss of normal heart function (heart failure). This may manifest as effort intolerance (exertional breathlessness), nocturnal breathlessness, or swelling of the legs or abdomen.
Atrial flutter is recognized on an electrocardiogram by presence of characteristic flutter waves at a regular rate of 240 to 440 beats per minute. Individual flutter waves may be symmetrical, resembling p-waves, or may be asymmetrical with a “sawtooth” shape, rising gradually and falling abruptly or vice versa. If atrial flutter is suspected clinically but is not clearly evident on ECG, acquiring a Lewis lead ECG may be helpful in revealing flutter waves.