Any condition causing left ventricular hypertrophy may produce left atrial enlargement as a secondary condition. Inadditon to what is stated by va_tony left atrial enlargement can occur in association with systemic hypertension, but, also aortic stenosis (restricted opening of the valve increasing gradient pressure), and hypertrophic cardiomyopathy.
Has hypertrophic cardiomyopathy been ruled out? Was the enlarged LA the result of an EKG output? Hypertrophic cardiology (chamber size is decreased and restricted), MVR and stenosis can/will compromise the filling phase and the reduction of cardiac output can cause chest pain, muscle fatique, shortness of breath, etc. if serious.
The atria are the upper chambers of the heart. Normal size range for the left atrium is between 2.0 and 4.0 cm. If the LA is larger than 4 cm, it's considered enlarged.
Enlarged atria are usually caused by untreated high blood pressure or leaky heart valves (e.g., mitral valve regurgitation). If you are fairly tall, there is a natural tendency towards enlarged atria.
At first, there are no sysmptoms of enlarged atria. However, as one ages, atrial fibrillation often develops (fast irregular heartbeat and palpatations) along with associated increased chances of a stroke.