In a 58-year-old patient with progressive dyspnea, paroxysmal nocturnal dyspnea, anterior wall hypokinesia, left ventricular ejection fraction 30%, and a new left bundle branch block, what is the next best investigation?

Coronary Angiography (Option C)

In this 58-year-old patient with heart failure symptoms (progressive dyspnea, paroxysmal nocturnal dyspnea), severely reduced left ventricular ejection fraction (30%), anterior wall hypokinesia, and new left bundle branch block, coronary angiography is the next best investigation to determine if ischemic heart disease is the underlying cause and whether revascularization could improve mortality and quality of life. 1, 2

Clinical Reasoning

Why Ischemia Must Be Excluded First

• Coronary artery disease is the most common cardiac cause of dyspnea and the major source of heart failure with reduced ejection fraction, making it the priority diagnosis to establish or exclude 1, 3
• The combination of anterior wall hypokinesia with severely reduced LVEF (30%) strongly suggests a regional wall motion abnormality consistent with coronary artery disease affecting the left anterior descending territory 1
• Patients with history of risk factors (age 58, presenting with heart failure) warrant evaluation for CAD as the underlying cause, as identifying ischemic etiology fundamentally changes management and prognosis 1

The New LBBB Changes Everything

• New LBBB in the setting of acute heart failure symptoms raises concern for acute coronary syndrome or acute myocardial infarction 4
• The European Society of Cardiology guidelines specifically state that new or presumed new left bundle branch block requires reperfusion therapy consideration, and measures to initiate treatment must be taken as soon as possible 4
• LBBB is generally associated with poorer prognosis and may be the first manifestation of more diffuse myocardial disease 5, 6
• The presence of left bundle branch block on ECG markedly increases the likelihood of underlying structural heart disease and left ventricular systolic dysfunction 4

Why Non-Invasive Testing Is Inadequate Here

• Myocardial perfusion imaging (Option A) has severely limited diagnostic accuracy in the presence of LBBB 4
• Exercise perfusion imaging with LBBB has specificity of only 33% and diagnostic accuracy of 36-60% due to false-positive septal defects from abnormal septal activation 4
• Even pharmacologic stress testing, while better than exercise, cannot definitively exclude significant coronary disease requiring revascularization in this high-risk presentation 4
• CT coronary angiography (Option B) has limited utility in high-risk patients and when revascularization is being considered—guidelines recommend proceeding directly to invasive angiography 1

Treatment Implications Drive the Decision

• If coronary revascularization is indicated (>10% of LV ischemia), it improves both symptoms and prognosis in heart failure with reduced ejection fraction 2
• The patient has LVEF ≤35% with new conduction abnormality—if ischemia is excluded, this patient may be a candidate for cardiac resynchronization therapy (CRT) or implantable cardioverter-defibrillator (ICD), but ischemia must be ruled out first 4
• Establishing whether this is ischemic versus non-ischemic cardiomyopathy fundamentally changes the treatment algorithm 4, 1

Why Other Options Are Incorrect

Chest X-Ray (Option D)

• Chest radiography is an initial diagnostic test that should have already been performed 4, 3
• While useful for identifying cardiomegaly and pulmonary congestion, normal chest radiography does not exclude cardiac disease, particularly early heart failure or diastolic dysfunction 1, 7
• This patient already has echocardiographic confirmation of severe LV dysfunction—chest X-ray adds no diagnostic value at this stage 3

Critical Clinical Pitfalls

• Do not delay coronary angiography in favor of non-invasive testing when new LBBB presents with heart failure symptoms—this combination suggests possible acute coronary syndrome requiring urgent evaluation 4
• Do not rely on stress testing in the presence of LBBB—the false-positive rate is unacceptably high and will lead to diagnostic confusion 4
• Do not assume non-ischemic cardiomyopathy without excluding coronary disease—CAD remains the most common cause of HFrEF and is potentially reversible with revascularization 1, 2

The Algorithm

1. Immediate coronary angiography to establish ischemic versus non-ischemic etiology 1, 2
2. If significant coronary disease found → revascularization (PCI or CABG) based on anatomy 2
3. If no significant coronary disease → optimize guideline-directed medical therapy (ACEI/ARB, beta-blocker, mineralocorticoid receptor antagonist) 4
4. After 3 months of optimal medical therapy, if LVEF remains ≤35% with LBBB and QRS ≥150 ms → consider CRT-D (cardiac resynchronization therapy with defibrillator) 4