A 62-year-old woman with chronic stable angina is being evaluated for the efficacy of her current antianginal regimen. She reports persistent chest discomfort on moderate exertion despite taking amlodipine and isosorbide mononitrate. Her physician suspects inadequate antianginal effect and wants to objectively assess myocardial ischemia and left ventricular function. Which investigation is most appropriate for this purpose?

## Investigation of Choice for Assessing Antianginal Efficacy and Ischemia ### Clinical Context The patient is on dual antianginal therapy (calcium channel blocker + long-acting nitrate) but has breakthrough symptoms. The goal is to: 1. Confirm persistent myocardial ischemia 2. Assess left ventricular function and wall motion 3. Guide escalation of therapy or referral for revascularization ### Why Dobutamine Stress Echocardiography is Correct **Key Point:** Dobutamine stress echocardiography (DSE) is the investigation of choice when exercise stress testing is contraindicated, inconclusive, or when simultaneous assessment of ischemia AND ventricular function is needed. **High-Yield:** DSE combines two critical assessments: 1. **Ischemia detection** — inducible wall motion abnormality (hypokinesis → akinesis) indicates ischemia 2. **Functional assessment** — directly visualizes LV ejection fraction, wall thickness, and diastolic function **Clinical Pearl:** In this patient, DSE is superior because: - She is already on antianginal drugs; DSE can be performed on therapy to assess residual ischemia - It provides real-time imaging of wall motion during increasing cardiac stress (dobutamine infusion) - Results guide decision to escalate medical therapy vs. refer for angiography/revascularization - No radiation exposure (unlike nuclear stress imaging) ### Advantages Over Alternatives | Investigation | Ischemia Detection | LV Function | When to Use | | --- | --- | --- | --- | | Dobutamine stress echo | Yes (wall motion) | Yes (real-time imaging) | Dual assessment needed; exercise contraindicated; on therapy | | Exercise stress test | Yes (ST changes) | No | Baseline screening; patient able to exercise | | Nuclear stress test | Yes (perfusion defect) | Yes (LVEF) | When echo windows poor; prior MI | | Resting echo | No | Yes | Baseline LV function; not diagnostic for ischemia | ### Interpretation **Positive DSE:** New or worsening wall motion abnormality at lower doses of dobutamine = residual ischemia despite current therapy → consider angiography for revascularization. **Negative DSE:** No inducible wall motion abnormality = adequate antianginal effect; continue current therapy.