Which of the following heart sounds is NOT typically associated with a myocardial infarction?

• A. S3 gallop
• B. Diminished S1
• C. Paradoxical S2 splitting
• D. Loud S2

Answer: (D)

Heart sounds in myocardial infarction reveal how the ventricle is impaired or how the conduction system is affected. An S3 gallop can appear when the ventricle is dilated or failing, indicating abnormal volume handling and systolic dysfunction after ischemic injury. A diminished S1 can occur with regional wall motion abnormalities or rapid heart rates that blunt the first heart sound, reflecting changes in how the mitral valve closes in the setting of ischemia. Paradoxical splitting of S2 happens when the aortic component is delayed, a scenario that can arise from left ventricular conduction delay such as a new left bundle branch block after MI; this split points to altered electrical activation of the heart. Loud S2 is not a typical consequence of myocardial infarction; it more often signals systemic or pulmonary hypertension or primary valvular disease. So loud S2 is the finding not typically associated with MI.