An 81-year-old woman with aortic stenosis is evaluated for increased shortness of breath and exercise intolerance. She was asymptomatic until 2 weeks ago when she noted increased shortness of breath with exertion. She reports no chest pain, orthopnea, paroxysmal nocturnal dyspnea, or palpitations. She has had no fever, chills, or recent procedures that might increase the risk for infective endocarditis. She has no other medical problems and takes no medications.
On physical examination, she is afebrile, blood pressure is 116/72 mm Hg, pulse rate is irregularly irregular at 112/min, and respiration rate is 12/min. No jugular venous distention is present. Cardiac auscultation reveals an irregular rhythm with a grade 3/6 crescendo-decrescendo systolic murmur loudest at the second left intercostal space with radiation to the carotid arteries. Bibasilar pulmonary crackles are present, as is 1+ bilateral lower extremity edema.
New-onset atrial fibrillation is the most likely cause of the patient's new symptoms. Aortic valve sclerosis, or valve thickening without outflow obstruction, is present in more than 25% of persons older than 65 years. Patients are often diagnosed when an asymptomatic murmur is auscultated or following an incidental echocardiographic finding. The progression from aortic sclerosis to stenosis is slow, and fewer than 20% of patients develop valve obstruction over the next 10 years. When mild stenosis is present, however, progressive valve stenosis proceeds more rapidly. Classic manifestations of aortic stenosis are angina, syncope, and heart failure. In early stages, aortic stenosis may present subtly with dyspnea or a decrease in exercise tolerance. Atrial fibrillation can be associated with rapid and severe clinical deterioration due to the more rapid rate and loss of atrial contribution to left ventricular filling. Angina occurs in more than 50% of patients with severe stenosis, due in part to maldistribution of coronary flow in the hypertrophied myocardium. Patients with aortic stenosis have increased sensitivity to ischemic injury, and subsequently have higher mortality. Frank syncope associated with aortic stenosis is rare, with prospective studies documenting sudden cardiac death rates less than 1% annually.
Endocarditis should be suspected if an abnormal murmur is heard on examination, particularly in patients with a compelling history or concurrent fever. Incidence is higher in patients with underlying valve abnormalities and prosthetic valves. Because of the absence of fever and the presence of atrial fibrillation as a more likely cause of clinical deterioration, infective endocarditis is unlikely.
Patients with a history of rheumatic fever may have involvement of multiple heart valves, but this is not the case in patients with degenerative aortic sclerosis. Furthermore, the physical examination findings of chronic mitral regurgitation include a holosystolic murmur, heard best at the apex, with radiation laterally or posteriorly. The auscultatory findings for mitral stenosis include an opening snap with a low-pitched middiastolic murmur that accentuates presystole. These findings are not present, making mitral stenosis or regurgitation unlikely.
Key Point
- In patients with aortic stenosis, atrial fibrillation can be associated with rapid and severe clinical deterioration due to the more rapid rate and loss of atrial contribution to left ventricular filling.
