Understanding a Complex Heart Case: Shortness of Breath After Previous Heart Attack

Table of Contents

• Background: Why This Case Matters
• Patient History and Medical Background
• Current Symptoms and Examination Findings
• Diagnostic Approach in Primary Care
• Differential Diagnosis: Considering All Possibilities
• ECG Analysis and Final Diagnosis
• Clinical Implications for Patients
• Limitations of This Case Analysis
• Patient Recommendations and Action Steps
• Source Information

Background: Why This Case Matters

This detailed case study from Massachusetts General Hospital demonstrates how doctors approach complex cardiac cases in patients with extensive heart histories. The patient had multiple serious heart conditions including previous heart attacks, heart failure, and dangerous heart rhythms that required an implanted defibrillator.

When such patients develop new symptoms like shortness of breath, the diagnostic process becomes particularly challenging. Doctors must balance the urgency of potentially life-threatening conditions with the need for careful consideration of all possible causes.

This case is especially relevant for patients with similar cardiac histories because it shows how subtle symptoms can indicate serious problems requiring immediate attention. The diagnostic reasoning process illustrated here can help patients understand how their doctors might approach similar situations.

Patient History and Medical Background

The patient was a 69-year-old man with an extensive cardiac history spanning several decades. His heart problems began unusually early in life when he experienced his first myocardial infarction (heart attack) in his third decade of life.

His medical history included:

• Premature coronary artery disease with first heart attack in his 30s
• Coronary artery bypass grafting (CABG) and stenting in his 50s
• Ischemic cardiomyopathy with chronically reduced ejection fraction of 31%
• Ventricular tachycardia (dangerously fast heart rhythm) leading to cardiac arrest
• Implantable cardioverter-defibrillator (ICD) placed 3 years earlier
• Bioprosthetic mitral valve replacement with subsequent valve deterioration
• Transcatheter valve-in-valve replacement 2.5 years earlier
• History of pulmonary embolism (blood clot in lungs) 4 years earlier
• Hypertension, iron-deficiency anemia, and other conditions

His medication regimen was complex, including aspirin, coumadin (warfarin, a blood thinner), furosemide (a diuretic), metoprolol (beta blocker), lisinopril (ACE inhibitor), dapagliflozin (diabetes medication), ranolazine (angina medication), atorvastatin (cholesterol medication), and several other drugs.

Notably, he had recently discontinued amiodarone (a powerful anti-arrhythmia medication) 6 months before this presentation due to concerns about liver function test abnormalities. His last echocardiogram showed a left ventricular ejection fraction of 31% with significant wall motion abnormalities.

Current Symptoms and Examination Findings

The patient developed symptoms suddenly 2 days before his clinic visit. While working and moving boxes, he experienced dyspnea (shortness of breath) on exertion that was worse than his usual baseline symptoms.

His usual baseline involved shortness of breath after climbing two to three flights of stairs, but this new symptoms occurred with minimal activity. The next day, he developed palpitations (awareness of heart beating) and felt lightheaded throughout the day.

Additional symptoms included:

• Nausea with intermittent retching
• Loss of appetite (only ate a slice of cheese all day)
• Fatigue and general feeling of being unwell
• Vision changes in his right eye described as "out of focus"

Importantly, he reported no chest pain or pressure, no presyncope (feeling faint) or loss of consciousness, no ICD discharge, no edema (swelling), orthopnea (shortness of breath when lying flat), or other concerning symptoms.

On physical examination, doctors found:

• Heart rate: 124 beats per minute (significantly elevated)
• Blood pressure: 84/59 mm Hg while sitting, 99/67 mm Hg while lying down (low)
• Temperature: 35.7°C (slightly low)
• Oxygen saturation: 99% on room air (normal)
• Appearance: diaphoretic (sweaty) and clammy but alert and lucid
• Heart sounds: possible S3 sound (associated with heart failure), minimal basilar rales (crackles in lung bases)
• Extremities: mild symmetric pedal edema (swelling in feet)

Laboratory tests from 2 weeks earlier showed mostly normal results including sodium 139 mmol/L, potassium 4.1 mmol/L, creatinine 0.91 mg/dL, hematocrit 44.0%, and NT-proBNP 669 pg/mL. His INR (measure of blood thinning) was 2.9, which was therapeutic for his condition.

Diagnostic Approach in Primary Care

The doctors faced a significant challenge in evaluating this complex patient in a primary care clinic setting. They recognized that the clinic environment might not have all the necessary tools to manage unstable cardiac conditions, and they needed to determine whether immediate emergency department transfer was necessary.

The diagnostic approach focused on several key considerations. First, the doctors acknowledged the patient's concerning history of ventricular tachycardia and ischemic cardiomyopathy—both dynamic and dangerous conditions that required immediate attention.

However, they also recognized the importance of not "anchoring" only on these obvious cardiac issues and remaining open to other diagnostic possibilities. This balanced approach is crucial in complex cases where multiple conditions could explain the symptoms.

The initial evaluation prioritized assessing hemodynamic stability given the patient's elevated heart rate and low blood pressure. Despite these concerning vital signs, the patient remained alert and lucid, suggesting adequate cerebral perfusion.

The physical examination provided additional clues that helped narrow the diagnostic possibilities. The absence of significant fluid overload signs (only minimal edema and rales) and the presence of warm skin without narrow pulse pressure helped guide the diagnostic reasoning.

Differential Diagnosis: Considering All Possibilities

The doctors systematically considered multiple possible causes for the patient's symptoms, organizing them into categories based on body systems and mechanisms.

Cardiac causes included:

• Arrhythmia (abnormal heart rhythm) - particularly likely given his history
• Decompensated heart failure (worsening heart function)
• Acute coronary syndrome (new heart blood flow problems)
• Valve failure or dysfunction

Pulmonary causes considered included pulmonary embolism (blood clot in lungs), but this seemed less likely given his therapeutic INR on warfarin and no missed doses. Pneumothorax (collapsed lung) was also considered but lacked supporting symptoms.

Other categories included hematologic causes like acute anemia, but no bleeding history was present. Metabolic causes like thyroid problems were possible given his recent amiodarone use, which can affect thyroid function.

The doctors paid particular attention to the patient's gastrointestinal symptoms (nausea, retching, loss of appetite) and visual symptoms, considering whether these might point to a unifying diagnosis. However, the chronic nature of the visual symptoms and absence of specific abdominal findings made gastrointestinal or neurological causes less likely.

After thorough consideration, the doctors determined that arrhythmia remained the most probable diagnosis, specifically slow ventricular tachycardia given the patient's history of this condition and recent discontinuation of amiodarone therapy.

ECG Analysis and Final Diagnosis

The critical diagnostic test was an electrocardiogram (ECG) performed during the clinic visit. The ECG showed a regular wide-complex tachycardia (fast heart rhythm with abnormal electrical patterns) consistent with ventricular tachycardia.

Doctors used the Brugada criteria, a well-established algorithm for distinguishing ventricular tachycardia from other arrhythmias. The patient's ECG met several key criteria:

• RS interval (measurement of electrical activity) of approximately 130 milliseconds in certain leads (normal is less than 100 milliseconds)
• Evidence of atrioventricular dissociation (upper and lower heart chambers beating independently)
• Specific QRS morphological features not typical of normal conduction patterns
• Extreme northwest axis on electrical mapping

Additional supporting evidence included the presence of a fusion beat (seventh beat in the tracing), which occurs when the heart is activated simultaneously by the abnormal rhythm and a normal beat. Intracardiac electrograms from the patient's ICD confirmed the diagnosis showing clear atrioventricular dissociation.

The final diagnosis was slow ventricular tachycardia, a potentially dangerous arrhythmia that can cause the symptoms the patient experienced—shortness of breath, palpitations, lightheadedness, and nausea due to reduced cardiac output.

Clinical Implications for Patients

This case has several important implications for patients with similar cardiac histories. First, it demonstrates that even subtle symptom changes can indicate serious cardiac issues requiring prompt attention.

Patients with complex cardiac histories should be particularly attentive to:

• New or worsening shortness of breath, especially with minimal exertion
• Palpitations or awareness of heart rhythm changes
• Lightheadedness or dizziness
• Unexplained nausea or gastrointestinal symptoms
• Changes in exercise tolerance or daily activity capacity

The case also highlights the importance of medication adherence, especially for blood thinners like warfarin, and regular follow-up with cardiology specialists. The recent discontinuation of amiodarone may have contributed to the recurrence of ventricular tachycardia in this patient.

For patients with implanted devices like ICDs, regular device checks are essential. This patient had his last ICD check 3 months before presentation, which was within appropriate monitoring intervals.

Limitations of This Case Analysis

While this case provides valuable insights, it's important to recognize its limitations. This is a single case study, which means the findings cannot be generalized to all patients with similar conditions.

The diagnostic process occurred in a specific clinical context at a major academic medical center with specialized expertise. The availability of immediate ECG and expertise in interpreting complex arrhythmias may not be available in all clinical settings.

Some diagnostic tests that might have provided additional information, such as thyroid function tests, were not available during the initial evaluation. The chronic nature of some symptoms (like visual changes) made interpretation more challenging.

The case also demonstrates how experienced clinicians can sometimes reach accurate diagnoses based on pattern recognition and clinical experience, which may be difficult to replicate in less specialized settings.

Patient Recommendations and Action Steps

Based on this case, patients with similar cardiac histories should consider the following recommendations:

1. Seek immediate medical attention for new or worsening cardiac symptoms, especially shortness of breath, palpitations, or lightheadedness
2. Maintain regular follow-up with your cardiologist and primary care physician, including regular device checks if you have an ICD
3. Adhere strictly to medication regimens, especially blood thinners and anti-arrhythmia medications
4. Keep detailed records of your symptoms, including when they occur, what makes them better or worse, and associated symptoms
5. Understand your specific cardiac condition and what symptoms might indicate worsening
6. Have an action plan for when symptoms develop, including knowing when to go to the emergency department versus when to call your doctor

For patients with implanted devices, it's important to understand how your device works and what to expect if it detects or treats an arrhythmia. Regular device checks are essential for ensuring proper function.

Source Information

Original Article Title: Case 34-2024: A 69-Year-Old Man with Dyspnea after Old Myocardial Infarction

Authors: Kevin Heaton, M.D., Emily K. Zern, M.D., Aferdita Spahillari, M.D., and Conor D. Barrett, M.D.

Publication: The New England Journal of Medicine, October 31, 2024

DOI: 10.1056/NEJMcpc2402505

This patient-friendly article is based on peer-reviewed research from the Case Records of the Massachusetts General Hospital. The original case discussion involved multiple specialists who contributed to the diagnostic reasoning and analysis.