Which heart sounds are typically heard with myocardial infarction?

Which heart sounds are typically heard with myocardial infarction?

• A. S3 gallop, diminished S1, paradoxical S2 splitting
• B. S4 Gallop Only
• C. Midsystolic Click
• D. Distant Heart Sounds

Answer: (D)

The key idea is that acute ischemia from a myocardial infarction often makes the left ventricle stiffer, so atrial contraction against a noncompliant ventricle produces a fourth heart sound (S4), a late diastolic gallop that signals diastolic dysfunction. This S4 can appear newly with MI as the ventricle loses compliance due to ischemia. An S3 would point more to volume overload and systolic failure developing later, not the initial MI. A midsystolic click is associated with mitral valve prolapse and is not related to MI. Distant or muffled heart sounds suggest pericardial effusion or tamponade, not MI by itself. So the finding most typical of myocardial infarction is an S4 gallop.

The key idea is that acute ischemia from a myocardial infarction often makes the left ventricle stiffer, so atrial contraction against a noncompliant ventricle produces a fourth heart sound (S4), a late diastolic gallop that signals diastolic dysfunction. This S4 can appear newly with MI as the ventricle loses compliance due to ischemia. An S3 would point more to volume overload and systolic failure developing later, not the initial MI. A midsystolic click is associated with mitral valve prolapse and is not related to MI. Distant or muffled heart sounds suggest pericardial effusion or tamponade, not MI by itself. So the finding most typical of myocardial infarction is an S4 gallop.