Hypertrophic CM Flashcards
What characterizes hypertrophic cardiomyopathy?
LV hypertrophy + absence of another cardiac, systemic, or metabolic disease producing the magnitude of hypertrophy
What is the prevelance of hypertrophic CM?
0.20%
How is hypertrophic CM passed on?
Autosomal dominant with variable expression and age-releated penetrance
What is the pathophysiology of hypertrophic CM?
11 different sarcomeric mutations have been identified but only 30% of hypertrophic CM patients have a genetic etiology
Who should get tested for hypertrophic CM?
Hypertrophic CM screening is recommended for 1st-degree and other close relatives; they should get an echo and a cardiac MRI (not genetic testing)
What is the histologic pathognomonic finding for hypertrophic CM?
Myocardial fiber disarray with interstitial and perivascular fibrosis
What is the most common phenotypic variant for hypertrophic CM?
Asymmetric hypertrophy (septum and anterior wall, 70%) > isolated basal septal hypertrophy (15-20%) > midventricdular septal hypetrophy (8-10%) > apical hypertrophy (<2%)
Who do you see apical hypertrophy more often in?
East Asian patients (<2% of overall patients)
What is the most common location of hypertrophy in hypertrophic CM?
Basal anterior septum with continuity with the anterior free wall
What are patients with hypertrophic CM at risk for?
Sudden cardiac death, LVOT obstruction, diastolic dysfunction, heart failure with systolic dysfunction, ventricular arrhythmias, atrial fibrillation with increased risk of stroke
What imaging findings are suggestive of increased risk of sudden cardiac death in patients with hypertrophic CM?
- Massive LVH (>/= 30mmHg)
- LV apical aneurysm
- systolic dysfunction (LVEF <50%)
- history of suspected cardiac syncope or family history of sudden cardiac death
Which patients with hypertrophic CM are at a higher risk of lifelong adverse events?
Patients with pathogenic sarcomeric gene variants and those diagnosed earlier in life
What % of patients have LVOT obstruction with hypertrophic CM?
75%
What is the peak LVOT gradient indicative of obstruction?
> /= 30mmHg (>/= 50mmHg is severe obstruction)
What is the most common cause of obstruction in hypertrophic CM?
Mitral-septal contact secondary to systolic anterior motion (SAM)
What are the principal mechanisms responsible for LVOT obstruction?
- Septal hypertrophy with narrowing of the LVOT; 2. Anatomic alterations in the MV apparatus (i.e. longer leaflets, anterior displacement of the pap muscles and MV apparatus)
What does systolic anterior motion of the MV lead to?
LVOT obstruction and MR (due to loss of leaflet coaptation)
What do you see on CW through the AV with LVOT obstruction?
Dagger-shaped or Shark-toothed profiled
What are other causes of LVOT obstruction outside of SAM?
- Anomalous papillary muscle (causes obstruction because of systolic apposition of the pap muscle and septum); 2. Apical hypertrophic CM (systolic apposition of the mid-LV walls leads to apical blood trapping with high apical chamber pressures leading to apical akinesis)
Why does diastolic dysfunction occur with hypertrophic CM?
Secondary to myocardial hypertrophy + ischemia + fibrosis + delayed inactivation from abnormal intracellular Ca reuptake + altered systolic-diastolic coupling
What does the MR jet look like with SAM?
The regurgitant jet is during mid-systole and posteriorly or laterally directed
Why do you get myocardial ischemia with hypertrophic CM?
Mismatch between O2 supply and demand; there is hypertrophy and microvascular dysfunction with impaired coronary flow reserve + arteriolar intimal and medial hyperplasia + myocardial bridging
What is myocardial bridging?
Overlying myocardial causing systolic compression of an epicardial coronary artery (can impair blood flow and cause ischemia)
What types of autonomic dysfunction do you see with hypertrophic CM?
Impaired HR recovery + inappropriate vasodilation + abnormal BP response to exercise (failure to increase SBP by 20mmHg or a drop in SBP during exercise > 20mmHg is a poor prognostic factor)
