What is the cause of increasing shortness of breath, worsened by lying down, in an elderly woman with a history of diabetes (Diabetes Mellitus), hypertension (High Blood Pressure), and ischemic heart disease (Coronary Artery Disease), presenting with pulmonary edema on chest X-ray and ST-elevation on ECG (Electrocardiogram)?

Acute ST-Elevation Myocardial Infarction (STEMI) Causing Acute Decompensated Heart Failure

This patient is experiencing an acute ST-elevation myocardial infarction (STEMI) with resultant acute decompensated heart failure and pulmonary edema, which is the direct cause of her orthopnea and shortness of breath. 1, 2

Clinical Reasoning

The combination of ST-elevations in inferior (II, III, aVF) and lateral leads (V5, V6) with pulmonary edema on chest X-ray in an elderly woman with multiple cardiac risk factors (diabetes, hypertension, ischemic heart disease) represents an acute myocardial infarction causing left ventricular dysfunction and backward heart failure. 3, 2

Why This Is STEMI-Induced Heart Failure

• Elderly patients with diabetes frequently present with atypical symptoms of acute coronary syndrome, including dyspnea without chest pain as an anginal equivalent 3, 4
• Acute pulmonary edema is predominantly a complication of elderly hypertensive patients with acute coronary syndromes (82% of cases), particularly non-ST elevation MI (NSTEMI) and unstable angina, though STEMI causes higher mortality 2
• The American Heart Association notes that patients with coronary heart disease presenting with acute pulmonary edema are generally older than those manifesting typical anginal symptoms, with dyspnea frequently substituting for chest pain in elderly patients 3
• Acute myocardial ischemia or infarction is a frequent cause of left-heart backward failure presenting with pulmonary edema and shortness of breath worsened by lying down (orthopnea) 3, 1

Pathophysiology

The ST-elevations indicate acute transmural myocardial ischemia causing acute systolic and diastolic dysfunction, which increases left ventricular end-diastolic pressure, leading to elevated pulmonary venous pressure and fluid shift into the pulmonary interstitium and alveoli 5, 3

• Pulmonary edema in acute coronary syndromes results from fluid redistribution rather than fluid accumulation, directed into the lungs because of acute heart failure with marked increase in systemic vascular resistance superimposed on insufficient myocardial functional reserve 5
• The European Society of Cardiology identifies acute myocardial ischemia/infarction as requiring specific urgent intervention when presenting with left-heart backward failure 3, 1

Critical Diagnostic Pitfalls to Avoid

Do not dismiss the absence of chest pain as ruling out acute myocardial infarction in this elderly diabetic woman—dyspnea is a well-recognized anginal equivalent in this population 3, 4

• The combination of ST-elevations on ECG with pulmonary edema mandates immediate consideration of acute coronary syndrome requiring urgent cardiac catheterization 1
• Normal vital signs do not exclude STEMI—elderly patients with diabetes and hypertension may not mount typical hemodynamic responses 3
• Clear lung sounds on initial examination do not rule out pulmonary edema, as radiographic findings may precede auscultatory findings 4

Immediate Management Algorithm

First Priority: Confirm STEMI and Activate Catheterization Lab

• Obtain high-sensitivity troponin immediately to confirm myocardial necrosis 4
• Activate cardiac catheterization lab for urgent percutaneous coronary intervention—this is the definitive treatment for STEMI 1
• Perform urgent transthoracic echocardiography to assess for regional wall motion abnormalities, ejection fraction, and mechanical complications (mitral regurgitation, ventricular septal defect) 3, 4

Second Priority: Treat Acute Pulmonary Edema

The European Society of Cardiology recommends immediate IV loop diuretics combined with vasodilators, supplemental oxygen or non-invasive ventilation for acute decompensated heart failure with pulmonary edema 1, 3

• Initiate non-invasive positive pressure ventilation (CPAP or BiPAP) immediately for pulmonary edema, which improves oxygenation and reduces work of breathing while medical therapy takes effect 1, 5
• Primary treatment consists of vasodilation plus diuretics, with vasodilators being the primary therapy for left-heart backward failure 3, 1
• IV loop diuretic dose should be equivalent to or higher than any chronic oral daily dose 1
• Add bronchodilators if wheezing ("cardiac asthma") is present 3, 1
• Morphine may be considered for severe dyspnea and anxiety, though use cautiously 3, 1

Critical Management Caveats

Do not use inotropes in this patient—they are indicated only for forward failure with low cardiac output and hypotension, not for pulmonary edema with normal blood pressure 1

• Do not give excessive fluids—this patient has backward failure with pulmonary edema requiring diuresis, not volume expansion 1
• Invasive ventilation with endotracheal intubation should be reserved for patients who fail non-invasive ventilation 1
• Monitor for hypotension with vasodilator therapy, particularly in elderly patients who may have volume depletion 6

Prognostic Considerations

Patients with STEMI complicated by acute pulmonary edema have significantly higher 30-day mortality (26%) compared to NSTEMI with pulmonary edema (9%) 2

• Ejection fraction <40% and peak creatine kinase MB concentration >100 μg/L are the main prognostic markers for 30-day mortality 2
• The larger infarct size in STEMI patients with pulmonary edema suggests more extensive acute systolic loss despite similarly reduced ejection fraction compared to NSTEMI 2
• In-hospital mortality predictors include diabetes, orthopnea, moderate-to-severely depressed left ventricular systolic function, acute myocardial infarction, hypotension/shock, and need for mechanical ventilation 7