The Cardiac Illness of General Lee
In the spring of 1863, Lee developed a cardiac illness characterized by severe chest pains. His physicians were Drs. Lafayette Guild and Samuel Merrifield Bemiss. His recovery from this illness was slow, and there has been much speculation regarding this illness and its relationship to the battle of Gettysburg that summer. The only reference that Lee ever made of this was in his letter to Jefferson Davis, dated August 8, 1863, from Orange, VA.
I have not yet recovered from the attack I experienced this spring. I am becoming more and more incapable of exertion, and thus am prevented from making the personal examinations and giving the personal supervision to the operations in the field which I feel to be necessary. I am so dull that in making use of the eyes of others I am frequently misled. Everything, therefore, points to the advantages to be derived from a new commander. 
Lee's health improved, and for six years he had no additional cardiac symptoms (Fig. 4). Indeed, Drs. Madison and Barton apparently were not aware of General Lee's previous illness until the fall of 1869, as evidenced by this quote:
During the campaign of 1863, General Lee contracted a severe laryngitis which culminated in pericardial inflammation... this trouble had gradually diminished, and we were not even made aware of its existence ... until October, 1869, when he had an attack of subacute pericarditis. During this attack... his respiration and rhythm of the heart were normal ... and there was no evidence of effusion. 
Lee himself described his chest pains quite precisely in this letter to his wife.
The warm weather has also dispelled some of the rheumatic pains in my back, but I perceive no change in the stricture in my chest. If I attempt to walk beyond a very slow gait, the pain is always there. 
In modern medicine, the description of exertional chest pains is unmistakable for the diagnosis of angina pectoris.[9,10] In addition to Madison and Barton, Lee was seen by at least nine other physicians during the course of his 1869-1870 illness, all of whom more or less agreed with the diagnosis of pericarditis. However, his 19th century physicians failed to recognize these signs, presumably due to the rarity of this condition in those times. It is also evident that the 1869-1870 illness had the same underlying cause as the 1863 illness based on the following letter.
My health is much better than when I left Virginia and I am quite comfortable again. I do not know that I can ever expect more. My late attack was an aggravation of the disease that I contracted during the war, and proceeded from a violent cold that seized me while the Army was before Fredericksburg. 
During the spring of 1870, Lee developed symptoms of chest pain at rest. The description in modern terms suggests the diagnosis of rest angina, which we know carries an ominous prognosis. Indeed, General Lee was to survive just six more months following the development of these symptoms.
South Med J. 2005;98(8):800-804. © 2005 Lippincott Williams & Wilkins
Cite this: The Lexington Physicians of General Robert E. Lee - Medscape - Aug 01, 2005.