Uncommon Presentations of Acute Coronary Syndrome

Introduction:

Acute coronary syndrome is a potentially life-threatening emergency that occurs due to insufficient blood supply to the heart tissue, which is accompanied by a heart attack or unstable angina. This happens either due to rupture of the plaque formed in the arteries causing clot formation, which clogs the arteries and hampers the blood flow. Timely diagnosis and effective management can result in positive treatment outcomes. Treatment options include medications and surgical interventions.

What Is Acute Coronary Syndrome?

Acute coronary syndrome is a condition that is associated with a significant reduction in the blood flow or sudden stoppage of blood supply to the heart, causing damage to the coronary tissues that may commonly present as a heart attack or unstable angina.

How Does Acute Coronary Syndrome Develop?

The plaque builds up in the arteries, which mainly consist of fat, cholesterol, and cells, blocking the blood supply. This atheromatous plaque may rupture due to inflammation releasing the thrombogenic material, which initiates platelet aggregation through a series of coagulation events, eventually forming a thrombus. The thrombus formed disrupts the blood supply to the coronary tissue. When the coronary tissue is deprived of the blood supply, it manifests in varied clinical symptoms.

What Are the Types of Acute Coronary Syndrome?

ACS (acute coronary syndrome) is classified into,

1. Unstable Angina:

• Refers to sudden, prolonged, unexpected chest pain or pressure at rest (stays more than 20 minutes).

• It is indicative of heart attack as there is acute coronary insufficiency.

• Increased, more frequent, and severe angina.

• ECG (electrocardiogram) changes include ST-segment depression, ST-segment elevation, or T-wave inversion.

• Cardiac markers like troponin levels are elevated.

• Unstable angina usually leads to myocardial infarction or arrhythmia or even sometimes may lead to death.

2. Non–ST-Segment Elevation Myocardial Infarction (NSTEMI):

• A non-ST-segment elevation myocardial infarction (NSTEMI) refers to a heart attack that is detected through blood tests and not by ECG changes.

• Coronary arteries are blocked partially.

• Detected by elevated cardiac markers like troponin I or troponin C and creatine kinase in the blood.

3. ST-Segment Elevation Myocardial Infarction (STEMI):

• An ST-segment elevation myocardial infarction (STEMI) refers to a severe heart attack that is detected both by blood tests and ECG changes.

• Blood flow to the coronary tissue is completely blocked for a long period, and a larger area of the myocardial tissue is affected.

• ECG changes show ST-segment elevation and also cardiac markers like troponin I or troponin C, and creatine kinase levels are elevated.

What Are the Atypical Clinical Features of Acute Coronary Syndrome (ACS)?

• Epigastric or back pain.

• Burning or stabbing pain, similar to pain during indigestion.

• Dyspnea.

• Jaw pain.

• Generalized weakness.

• Sweating.

• Syncope (fainting).

• Palpitation.

• Autonomic neuropathy in diabetic people may also end up having atypical features.

• Atypical symptoms associated with ACS usually mislead the diagnosis, and most of the delays in the treatment can negatively affect the treatment outcomes.

Typical symptoms are,

• Radiating pain in the shoulder, arm, neck, back, or belly region.

• Discomforts like tightness, squeezing, burning, choking, and an aching sensation.

• Discomfort is not relieved even after taking medication.

• Anxiety.

• Nausea.

• Arrhythmias.

• Women and the elderly are more commonly affected.

What Are the Complications of ACS?

• Electrical dysfunction like arrhythmias (irregular heartbeat).

• Myocardial dysfunction involves heart failure, interventricular septum rupture, ventricular aneurysm, formation of mural thrombus, and cardiogenic shock.

• Valvular dysfunction such as mitral regurgitation.

• Pericarditis (inflammation of the membrane covering the heart).

What Are the Risk Factors of ACS?

• Elderly people.

• High blood pressure.

• High blood cholesterol.

• Smoking tobacco.

• Unhealthy lifestyle activities like sedentary life and unhealthy diet choices.

• Obesity or overweight.

• Diabetes.

• Familial history of having chest pain, heart attacks, or stroke.

• COVID-19 infection.

How Is ACS Diagnosed?

1. ECG (Electrocardiogram) Changes:

• ECG is a vital diagnostic tool in the case of ACS and should be initiated as soon as the patient presents in the department.

• It helps in differentiating STEMI (ST-segment elevation myocardial infarction) and NSTEMI (non–ST-segment elevation myocardial infarction).

• The decision-making becomes easy, as fibrinolytic therapy and immediate catheterization are employed to treat STEMI, thus initiating timely management.

• For STEMI, initial ECG changes are of great importance as they show ST-segment elevation ≥ 1 mm in 2 or more contiguous leads.

• The ST-segment elevation is consistent with the QRS complex; ST-segment elevation in at least two precordial leads greater than 5 mm strongly suggests myocardial infarction.

2. Cardiac Markers:

• Cardiac enzymes such as CK-MB (creatine kinase- MB isoenzyme).

• Cell contents such as troponin I, troponin T, and myoglobin are important diagnostic aids.

• These markers are released into the bloodstream as a result of myocardial degeneration. These markers appear at specific times based on the time of injury and at specific levels.

• Troponins (cTn) is the most sensitive and specific marker test available.

• Very low levels of troponin (T or I), such as 0.003 to 0.006 ng/mL (3 to 6 pg/mL), can be detected.

• Patients suspected of having an ACS should undergo a hs-cTn assay as soon as possible again after two to three hours. Troponin levels should be assessed from zero to six hours if a standard cTn assay is used.

3. Coronary Angiography:

• Coronary angiography usually is accompanied by PCI (percutaneous coronary intervention), such as angioplasty and stent placement, as soon as possible, immediately after myocardial infarction, to avoid morbidity and mortality rates.

• Angiography is indicated immediately in patients with STEMI, patients suffering from consistent chest pain despite medical therapy, and patients with certain complications such as elevated cardiac markers, cardiogenic shock, acute mitral regurgitation, ventricular septal defect, and unstable arrhythmias.

• Patients with uncomplicated NSTEMI or unstable angina with resolved symptoms should get the angiography done within 24 to 48 hours of hospitalization so that lesions can be detected and treated.

• Coronary angiography is also useful in patients suffering from ischemia, detected by ECG findings and symptoms, hemodynamic instability, and recurrent ventricular tachyarrhythmias. Also, angiography is indicated in STEMI patients who are susceptible to ischemia, on stress imaging, or if the ejection fraction is less than 40 percent before getting discharged from the hospital.

How Is ACS Treated?

• Anticoagulants or blood thinners, like Aspirin or Heparin, are administered to dissolve the clots and prevent further formation.

• Angiotensin-converting enzyme (ACE) inhibitors such as Ramipril, Trandolapril, Captopril, and Lisinopril are used to lower blood pressure.

• Beta-blockers such as Metoprolol succinate, Carvedilol, or Bisoprolol are given to regulate blood pressure and decrease the heart rate.

• Nitroglycerin is given to improve blood flow and relieve chest pain.

• Painkillers such as Morphine or Fentanyl are administered.

• Statins such as Atorvastatin and Simvastatin are used to lower blood cholesterol levels.

• Thrombolytic agents such as Tenecteplase, Alteplase, Reteplase, Streptokinase, and Anistreplase are given to dissolve blood clots within the first 12 hours after a heart attack.

Conclusion:

Acute coronary syndrome is an emergency condition with an increased risk of certain complications and sometimes even death if misdiagnosed or not treated promptly. Often, atypical symptoms may mislead the diagnosis and effective management. A healthcare provider should have adequate knowledge of typical and atypical features, diagnosis, and management to ward off complications. ACS can be prevented if the underlying risk factors are checked and managed effectively.