Rate-Related Septal Infarct Pattern

A 64-year-old asymptomatic woman with a 10-year-history of hypertension was referred for blood pressure control. She had no other significant medical history. The patient denied exertional chest discomfort or dyspnea. Her medications included atenolol, lisinopril, and hormone replacement therapy.

Drs Jonathan Greenblatt, Alexander Butkevich, and Stanley Reichman of New York write that tachycardia was noted on examination. Routine laboratory test results were unremarkable. The ECG revealed sinus tachycardia of 108 beats per minute, new left axis deviation, left anterior fascicular hemiblock, and Q waves in leads II, aVF, and V4 through V6 (A). These findings were not apparent on subsequent ECGs with heart rates less than 100 beats per minute (B). The results of a treadmill thallium study were normal.

Carotid sinus massage performed at a later visit slowed the heart rate, normalized the axis, and resulted in the disappearance of the left anterior fascicular hemiblock and the septal myocardial infarction pattern (C).

There are no cardiovascular clinical implications for patients with rate-related left anterior fascicular hemiblocks. This patient's normal stress thallium study obviated the need for additional cardiac testing. She was asymptomatic and doing well 4 months later.