Ischemic cardiomyopathy (ICM) is a specific type or advanced stage of coronary artery disease (CAD). It is clinically characterized by new-onset heart failure or left ventricular dysfunction, often accompanied by various arrhythmias and cardiac enlargement resembling dilated cardiomyopathy. The underlying pathophysiology involves chronic myocardial ischemia and hypoxia caused by coronary atherosclerotic lesions, leading to myocardial cell loss, necrosis, fibrosis, and scar formation.
Clinical manifestations
Congestive ischemic cardiomyopathy
Angina pectoris is one of the common symptoms. Most patients have a clear history of coronary artery disease, and the majority have experienced one or more myocardial infarctions. However, angina is not a necessary symptom; some patients present only with silent myocardial ischemia until congestive heart failure develops. As the disease progresses, patients with angina may experience worsening congestive heart failure, while angina episodes may gradually decrease or even disappear, leaving symptoms such as chest tightness, fatigue, dizziness, and dyspnea.
Heart failure often occurs at a certain stage of ischemic cardiomyopathy. Some patients develop heart failure early during episodes of chest pain or myocardial infarction, while others develop it at later stages. This is caused by diastolic and systolic dysfunction of the myocardium due to acute or chronic ischemic necrosis. Common symptoms include exertional dyspnea, orthopnea, and paroxysmal nocturnal dyspnea in severe cases, along with fatigue and weakness. On auscultation, the first heart sound may be diminished, and a mid-to-late diastolic gallop may be heard. Scattered moist cracklings may be detected at the lung bases. In advanced stages, if right heart failure develops, symptoms such as anorexia, peripheral edema, and right upper abdominal discomfort may occur. Physical examination may reveal jugular venous distension, an enlarged cardiac silhouette, hepatomegaly with tenderness, and a positive hepatojugular reflux sign.
Chronic ischemia leads to myocardial necrosis, stunning, hibernation, and focal or diffuse fibrosis, eventually resulting in scar formation and electrical activity disturbances. Various arrhythmias may occur, with ventricular premature beats, atrial fibrillation, and bundle branch block being the most common.
Intracardiac thrombus formation with embolic events is more common in the following cases:
- Significantly enlarged cardiac chambers
- Atrial fibrillation without adequate anticoagulation therapy
- Markedly reduced cardiac output
Restrictive ischemic cardiomyopathy
Although most patients with ischemic cardiomyopathy exhibit symptoms similar to dilated cardiomyopathy, a small subset primarily presents with left ventricular diastolic dysfunction, while systolic function remains normal or only mildly impaired. This condition resembles restrictive cardiomyopathy and is therefore referred to as restrictive ischemic cardiomyopathy or stiff heart syndrome.
These patients often experience exertional dyspnea and/or angina, along with activity limitations. Recurrent episodes of pulmonary edema may also occur.
Diagnosis
The diagnosis of ischemic cardiomyopathy requires meeting the following criteria:
- Evidence of myocardial necrosis or ischemia
- Significant cardiac enlargement
- Clinical manifestations and/or laboratory findings of heart failure
Evidence of myocardial necrosis or ischemia includes:
- A history of prior cardiac events
- A history of revascularization procedures
- Objective evidence of myocardial ischemia under resting or stress conditions, even without a known history of acute coronary syndrome
Examples of objective evidence include pathological Q waves on ECG indicating myocardial necrosis, regional wall motion abnormalities observed on echocardiography, and significant coronary stenosis confirmed by coronary CTA or coronary angiography
Complications of coronary artery disease, such as ventricular septal rupture, ventricular aneurysm, and mitral regurgitation due to papillary muscle dysfunction, should be excluded. Other cardiac diseases or non-cardiac causes of cardiac enlargement and heart failure should also be ruled out.
Differential diagnosis
Other causes of cardiac enlargement and heart failure must be differentiated.
Prevention
Early prevention is crucial, focusing on aggressively managing risk factors for coronary artery disease.
Treatment goals are to:
- Improve myocardial ischemia
- Prevent recurrent myocardial infarction and death
- Correct arrhythmias
- Actively manage heart failure (treatment principles, including pharmacological and device-based therapies, are similar to those for chronic heart failure)
For patients with viable myocardium in ischemic regions, revascularization can significantly improve myocardial function.
New therapeutic techniques, such as autologous bone marrow stem cell transplantation and vascular endothelial growth factor gene therapy, have been applied in clinical practice, offering new hope for the treatment of ischemic cardiomyopathy.
For end-stage patients, artificial hearts or heart transplantation may be considered.