Hypertrophic cardiomyopathy (HCM) manifests with or without obstruction. Obstructive HCM , (ie HOCM) is more often symptomatic .However , the risk of arrhythmias, sudden death, and some degree of diastolic dysfunction are common in both.
ECG, clinical examination are generally not sensitive to identify obstruction in HCM .Echocardiogram is the easiest way to identify the obstruction (gradients> 3o mmhg across LVOT are considered significant ).LV angiogram ,MRI, CT scans are rarely necessary today.
However , the following clinical clues will help us to suspect significant obstruction in HCM
- Class 2 or 3 dyspnea.
- Exertional syncope
- Exertional angina
- Pulsus bisferiens (Two peaks in systole )
- Sustained , double apical impulse often indicate obstruction.
- Presence of Mitral regurgitation ( 20% can have MR without obstruction due to intrinsic abnormalities of mitral valve )
* It should be realised , valsalva induced MR /LVOTO may occur in many of the non obstructive HCM.
What happens to clinical signs of obstruction with medical therapy(Beta blockers etc)
One would expect these signs to regress or disappear, but it rarely happens. The pulse , the murmur show little change . This implies , the main mechanism of beneficial effect could be in heart rate reduction , and improvement in the diastolic properties of left ventricle.