A 62-year-old man with a history of rheumatic heart disease presents to your office with complaints of exertional dyspnea. No constitutional complaints are present. He had undergone a mitral valve replacement with a bileaflet tilting disk mechanical valve 11 years prior. He is normotensive with a heart rate of 73 bpm. On examination, you note a grade II/VI holosystolic murmur at the apex. An echocardiogram is performed, which reveals normal LV and RV function. Peak mitral gradient is 30 mmHg. Mean transmitral gradient is 7 mmHg. Pressure half-time is 80 milliseconds.
What is your next diagnostic step?
Transesophageal echocardiogram. By examination, the patient has mitral insufficiency. The echocardiogram is consistent with this, with an elevated peak transmitral gradient. Pressure half-time is not prolonged; thus there does not appear to be any significant stenosis (gradients elevated owing to increased flow from regurgitant volume). A TEE would be the most useful to confirm the diagnosis. Fluoroscopy may identify partial dehiscence, but would not be helpful if there were a leak in the setting of a well-seated valve. There is no evidence for stenosis, where fluoroscopic evaluation of leaflet motion could be diagnostic. There is no clinical evidence for endocarditis.
Which of the following would be the expected physical findings in this patient if the valve were functioning normally?
Prominent closing click, soft and brief diastolic rumble. The bileaflet mechanical valves do not typically produce a loud opening sound, but do have prominent closing sounds. A brief diastolic rumble may be heard in a normally functioning prosthetic valve in the mitral position.
If the patient had a ball-and-cage valve instead, what would you expect to hear?
Prominent opening and closing clicks, soft and brief diastolic rumble. With the ball-and-cage valves, one would expect to hear the opening click as well.
Recommended antithrombotic therapy for a patient with a mechanical mitral valve replacement without a prior thromboembolic event or other high-risk features is:
Warfarin therapy with a target INR of 2.5 to 3.5 plus aspirin 75 to 100 mg. All patients with a mechanical valve require warfarin. The risk of thromboembolic events is higher for prosthetic valves in the mitral position; therefore, the recommended therapeutic range is higher than that for mechanical valves in the aortic position. The addition of low-dose aspirin (75 to 100 mg) further reduces the risk of thromboembolic event and reduces mortality from cardiovascular disease. Therefore, aspirin is recommended for all patients with valvular prostheses. Higher doses of aspirin have not been shown to be beneficial and increase the bleeding risk.
A 65-year-old man presents to your office for evaluation of valvular heart disease. He is asymptomatic. He walks 5 miles a day without difficulty. An echocardiogram reveals severe AS, with a maximum aortic jet velocity of 4.7 m/s by Doppler echocardiography. LV systolic function is preserved. There is mild LV hypertrophy (wall thickness 1.4 cm). He walks on a treadmill for 9 minutes, with a normal hemodynamic response.
Continued observation is recommended. What do you tell him is his yearly risk of sudden death, provided he remains asymptomatic?
<2%. In the absence of symptoms, natural history studies would suggest a relatively low risk of sudden death.