Differential Diagnosis
- Single most likely diagnosis
- Hypertrophic Cardiomyopathy (HCM): The presence of a small left ventricular size, mild concentric left ventricular hypertrophy, and an LVOT gradient that increases with Valsalva maneuver are all characteristic findings of HCM. The recurrent syncope following coughing can be attributed to the dynamic outflow obstruction that worsens with decreased preload (e.g., during Valsalva) or increased contractility, which can occur with the increased intrathoracic pressure during coughing.
- Other Likely diagnoses
- Aortic Stenosis: Although less likely given the description of "mild concentric left ventricular hypertrophy," significant aortic stenosis could lead to an LVOT gradient and symptoms of syncope, especially if the stenosis is severe. However, the increase in gradient with Valsalva is more characteristic of HCM.
- Cardiac Sarcoidosis: This condition can lead to left ventricular hypertrophy and dysfunction, potentially causing an outflow tract obstruction. However, it would be less likely to present with the specific findings of increased LVOT gradient with Valsalva.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Aortic Dissection: Although the clinical presentation does not strongly suggest aortic dissection, any condition that causes chest pain or syncope and involves the aorta must be considered due to its high mortality rate. The increase in LVOT gradient with Valsalva could potentially be seen in the context of a dissection affecting the aortic root, but this would be an uncommon presentation.
- Pulmonary Embolism: While less directly related to the cardiac findings, recurrent syncope following coughing could potentially be related to a pulmonary embolism, especially if the coughing is a result of a pulmonary issue. This diagnosis is critical to consider due to its potential for high mortality if untreated.
- Rare diagnoses
- Fabry Disease: A genetic disorder that can lead to left ventricular hypertrophy, but it would be an uncommon cause of the specific combination of findings presented, including the dynamic LVOT obstruction suggested by the increase in gradient with Valsalva.
- Left Ventricular Non-Compaction: A rare cardiomyopathy characterized by a spongy appearance of the left ventricle. While it could potentially lead to outflow tract obstruction, it is less likely to present with the specific features described, such as an increase in LVOT gradient with Valsalva maneuver.