A 28-year-old man with a hypertrophic cardiomyopathy presents to your clinic to establish care. His last visit to his previous health care provider was one year ago. Since moving, he reports, he has had “difficulty” finding the time for an office visit.

Five years ago, the patient underwent a myomectomy to correct left ventricular outflow tract obstruction; he has subsequently been asymptomatic—at least, until about two months ago. He reports that in general he can do anything he wishes without limitations, but he now has more fatigue than usual, adding “some days are worse than others.” He has had recent episodes of lightheadedness, particularly with exertion, and now notices occasional palpitations. 

Medical records accompanying the patient include an echocardiogram performed one-and-a-half years ago, documenting a left ventricular (LV) ejection fraction of 68% with an LV peak gradient of 25 mm Hg at rest, increasing to 60 mm Hg with the Valsalva maneuver.  The interventricular septum measures 2.2 mm, compared to a posterior wall measurement of 1 mm. 

Medical and surgical histories are significant only for the diagnosis and procedure listed above. The social history is remarkable for occasional tobacco and marijuana use and weekend alcohol binges. The patient has never had alcohol-related blackouts. His medication list includes atenolol and verapamil.

Vital signs include a height of 6’2”; weight, 230 lb; blood pressure, 110/62 mm Hg; pulse, 60 beats/min; respiratory rate, 14 breaths/min; and O2 saturation, 97% on room air. The patient is pleasant and in no distress. The lungs are clear in all fields, there is no jugular venous distention, and the cardiac exam reveals a regular rate and rhythm, no gallops, and a grade III/VI systolic ejection murmur heard throughout the precordium. There is no peripheral edema. The remainder of the physical exam is normal.

As part of the establishment of care, an ECG is obtained and shows: a ventricular rate of 60 beats/min; PR interval, 184 ms; QRS duration, 178 ms; QT/QTc intervals, 506/506 ms; P axis, 74°; R axis, 51°; and T axis, 183°. What is your interpretation of this ECG?

ANSWER

The ECG shows normal sinus rhythm, left atrial enlargement (LAE), and a left bundle-branch block (LBBB). Left atrial enlargement is characterized by a P-wave duration of 0.12 seconds or more in the frontal plane (best seen in lead II), broad or notched P waves in the limb leads, and/or negative terminal P waves with a duration of 0.04 seconds or more and a depth of 1 mm or more. General ECG criteria for left ventricular hypertrophy include tall R waves in LV leads (V₄ to V₆), deep S waves in RV leads (V₁ to V₃), delayed intrinsic deflections in V₆ (onset of QRS to peak R 0.05 seconds or more), widened QRS/T angle (left ventricular strain pattern), and a leftward shift of the frontal plane QRS axis. LAE may also be associated with LBBB, as in this case.