A 30-year-old woman is referred for a pre-insurance examination. She has no complaints. She is active and runs with her large dog about 1 hour daily (4–5 miles). She has no exercise limitations and...

A 30-year-old woman is referred for a pre-insurance examination. She has no complaints. She is active and runs with her large dog about 1 hour daily (4–5 miles). She has no exercise limitations and was hiking at an elevation of 3,030 m in the Rockies last summer. On examination, her pulse rate is 50 beats per minute, blood pressure is 120/80 mm Hg, and she is thin. On cardiac examination, there is a normal fi rst heart sound and normal splitting; an early low-pitched diastolic sound is consistent with a third heart sound (S 3 ). Th ere is a grade 1 to 2 midsystolic murmur at the left upper sternal border. Th e murmur disappears with the Valsalva maneuver. Carotid upstrokes are normal, and the jugular venous pressure is normal. No systolic clicks can be appreciated at rest or with the squat-to-stand maneuver. Th e electrocardiogram shows sinus bradycardia (heart rate 48 beats per minute) but is otherwise normal. What further cardiac testing needs to be done? a. Cardiac catheterization to measure a gradient across the mitral valve b. Stress echocardiography c. Treadmill ECG d. No additional testing e. Holter monitoring