Question

A $62$-year-old woman presents to the outpatient cardiology office for evaluation of chest discomfort. Over the past month, she has experienced multiple episodes of a dull, left-sided chest ache that consistently occurs when climbing the two flights of stairs to her apartment. The pain reliably resolves after $5$ minutes of rest. She has a history of type 2 diabetes mellitus, hypertension, and chronic kidney disease stage 4. Her current medications include amlodipine, lisinopril, and insulin glargine.

Vital signs are temperature $36.8^\circ$ C ($98.2^\circ$ F), blood pressure $146/86$ mmHg, heart rate $74$/min, and respiratory rate $14$/min. Physical examination reveals a normal point of maximal impulse, normal $S_1$ and $S_2$, and no murmurs or gallops. Lungs are clear to auscultation. There is no lower extremity edema.

Recent laboratory studies show:

A resting $12$-lead electrocardiogram shows sinus rhythm with a QRS duration of $145$ ms, broad notched R waves in leads I, aVL, $V_5$, and $V_6$, and deep S waves in leads $V_1$ and $V_2$. No prior electrocardiograms are available for comparison.

Which of the following is the most appropriate next step in the diagnostic workup for this patient's chest pain?