Can moderate mitral valve regurgitation cause syncope and fatigue?

Can Moderate Mitral Regurgitation Cause Syncope and Fatigue?

Yes, moderate mitral regurgitation can cause both fatigue and, less commonly, syncope, though syncope is not a typical presenting symptom and should prompt evaluation for other causes including arrhythmias or concurrent structural disease.

Fatigue in Moderate Mitral Regurgitation

Fatigue is a well-recognized symptom of moderate mitral regurgitation and results from reduced forward cardiac output and chronic volume overload.

• The predominant clinical symptoms in chronic mitral regurgitation include dyspnea and fatigue resulting from pulmonary venous hypertension and low cardiac output 1
• Patients with mitral regurgitation commonly present with fatigue as a cardinal symptom, along with dyspnea and orthopnea 2, 3
• The pathophysiology involves reduced forward stroke volume due to the regurgitant fraction, which compromises systemic perfusion and causes exercise intolerance and fatigue 1
• Even moderate mitral regurgitation can cause significant symptoms in some patients, especially during exertion, when the regurgitant volume may worsen dynamically 4

Mechanism of Fatigue

• Mitral regurgitation causes blood to flow backward from the left ventricle into the left atrium during systole, leading to elevated left atrial and pulmonary venous pressures, which contributes to both pulmonary congestion and reduced forward output 4
• Exercise or catecholamine stimulation worsens symptoms by decreasing diastolic filling time and potentially increasing myocardial ischemia, leading to increased dyspnea and fatigue 5, 4
• The chronic left ventricular volume overload leads to left ventricular dilation and, over time, contractile dysfunction, which further compromises cardiac output 2

Syncope in Moderate Mitral Regurgitation

Syncope is NOT a typical symptom of isolated moderate mitral regurgitation and should raise suspicion for alternative or concurrent diagnoses.

When Syncope Occurs with Mitral Regurgitation

• Arrhythmias are the most important cause of syncope in patients with mitral regurgitation, particularly in those with mitral valve prolapse who may develop malignant ventricular arrhythmias 6
• Patients with mitral valve prolapse and mild-to-moderate mitral regurgitation can present with syncope, presyncope, or cardiac arrest due to ventricular tachycardia, even with normal left ventricular function 6
• Syncope in patients with moderate mitral regurgitation may indicate mitral valve prolapse syndrome, where symptoms such as palpitation, chest pain, fatigue, orthostatic phenomena, and syncope occur due to metabolic neuroendocrine abnormalities rather than the valve lesion itself 3
• The development of atrial fibrillation or other tachyarrhythmias in patients with mitral regurgitation can precipitate syncope, particularly if there is concurrent left ventricular dysfunction 7

Critical Pitfall to Avoid

• Do not attribute syncope to moderate mitral regurgitation without excluding arrhythmias, concurrent structural disease (especially aortic stenosis or hypertrophic cardiomyopathy), or neurally-mediated reflex mechanisms 7
• Syncope occurring during exercise in a patient with valvular disease warrants hospitalization and urgent evaluation, as it may indicate severe underlying pathology 7
• Structural cardiac disease is often present in older syncope patients, but it is more often the arrhythmias associated with structural disease that cause symptoms rather than the structural lesion itself 7

Clinical Evaluation Algorithm

For Fatigue in Moderate Mitral Regurgitation:

1. Confirm the severity and mechanism of mitral regurgitation with echocardiography, assessing left ventricular size, left atrial size, and left ventricular ejection fraction 4
2. Assess for left ventricular dysfunction, as even mildly reduced LVEF may indicate reduced ventricular reserve in mitral regurgitation (LVEF overestimates true LV performance in regurgitant lesions) 7, 5
3. Consider stress echocardiography if symptoms seem disproportionate to resting severity, as mitral regurgitation can worsen dynamically with exercise 7, 4
4. Initiate medical therapy with afterload reduction (ACE inhibitors or ARBs) and diuretics for symptomatic relief 7

For Syncope in a Patient with Moderate Mitral Regurgitation:

1. Obtain 12-lead ECG immediately to assess for arrhythmias, conduction abnormalities, or signs of ischemia 7
2. Perform ambulatory ECG monitoring (Holter or event monitor) to detect paroxysmal arrhythmias, particularly in patients with mitral valve prolapse 6
3. Reassess mitral regurgitation severity with echocardiography, as dynamic worsening may occur with stress or tachycardia 7
4. Evaluate for concurrent structural disease, particularly aortic stenosis, hypertrophic cardiomyopathy, or pulmonary hypertension, which are more typical causes of syncope 7
5. Consider electrophysiology study if malignant ventricular arrhythmias are suspected, especially in patients with mitral valve prolapse, inferolateral repolarization changes, or complex ventricular ectopy 6
6. Hospitalize patients with syncope and known significant heart disease, syncope during exercise, or family history of sudden death 7

High-Risk Features Requiring Urgent Evaluation

• Syncope in patients with mitral valve prolapse, particularly with inferolateral repolarization changes, complex ventricular ectopy, or markedly myxomatous valve, may indicate higher risk of sudden death 6
• Patients presenting with syncope, out-of-hospital cardiac arrest, or recurrent presyncope with mitral valve prolapse and mild mitral regurgitation are at risk despite normal left ventricular function 6
• Mitral valve surgery may not provide control of ventricular arrhythmias in these high-risk patients, and antiarrhythmic therapy or implantable cardioverter-defibrillator may be necessary 6