84. Case Report: Hypertrophic Cardiomyop...

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The CardioNerds Cardiology Case Reports series shines light on the hidden curriculum of medical storytelling. We learn together while discussing fascinating cases in this fun, engaging, and educational format. Each episode ends with an “Expert CardioNerd Perspectives & Review” (E-CPR) for a nuanced teaching from a content expert. We truly believe that hearing about a patient is the singular theme that unifies everyone at every level, from the student to the professor emeritus.

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Patient Summary

A man in his mid-70s with history of hypertension and diabetes presented with chest pain and ST elevation in V1-V3. Two weeks prior to his presentation he was diagnosed with HoCM after several months of progressive dyspnea. TTE at that time showed HCM with resting left ventricular outflow gradient of 35 mmHg and 83 mmHg with valsava and systolic anterior motion (SAM) of the mitral valve. Join the Brown University Cardionerds as they take us through the differential of chest pain in HCM, approach to wall motion abnormalities, and the fascinating management questions that arise.

Case Media

Episode Schematics & Teaching

The CardioNerds 5! – 5 major takeaways from the #CNCR case

1. What’s the differential for LVH and what findings are more suggestive of HCM?

• Causes for LVH can be either pathological or physiological. Pathological causes include infiltrative diseases like hypertrophic cardiomyopathy (HCM), Amyloidosis, or Fabry disease and inflammatory diseases like myocarditis.
• Physiological causes are due to remodeling from increased cardiac output or workload like in athletic heart or from a high afterload state such as in aortic stenosis and hypertension.
• In hypertension, AS, and athletic heart, LV hypertrophy is more commonly concentric and rarely exceeds 15mm. In HCM, LV hypertrophy is more commonly asymmetric (basal anteroseptum > posterior wall), often >15mm, and typically involves the basal ventricular septum.
• Differentiating pathologic versus physiologic causes of LVH can typically be done from a detailed history and exam (e.g., evidence of hypertrophy out of proportion to pressure overload, multisystem involvement). Cardiac MRI can be used to differentiate between HCM and other phenocopies. In HCM, LGE is usually seen at the insertion point of the LV and RV or the most hypertrophied myocardial regions whereas in amyloidosis, endomyocardial LGE is more characteristic.

1. What are some characteristic exam findings seen in HoCM?

• Systolic murmur at the left sternal border can be heard in patients with obstructive HCM (HoCM). The murmur is a result of LVOT obstruction due to systolic anterior motion (SAM) of the mitral valve and LV basal septal hypertrophy.
  • Maneuvers that decrease preload, such as Valsalva or going from a sitting to upright position, will enhance the obstruction and increase the intensity of murmur.
  • Maneuvers that increase the preload or afterload, such as squatting or handgrip, will decrease the intensity of murmur.
  • Additionally, mitral valve pathology – whether a primary valve process or secondary to SAM/ abnormalities in the chordae – can lead to murmurs of mitral insufficiency. These murmurs will typically be best heard at the apex. The murmur associated with SAM will be mid to late peaking as the anterior leaflet is pulled away from the posterior leaflet, unlike the holosystolic murmur associated with intrinsic MV pathology.
• Pulsus bisferiens describes an aortic waveform with two peaks per cardiac cycle that’s characteristic of dynamic LVOT. The onset of systole leads to the initial peak in aortic waveform. Then the narrowing of LVOT leads to a transient occlusion, causing a midsystolic dip in the aortic waveform. Lastly, towards the end of systolic, the ventricle overcomes the obstruction, leading to the second peak in the aortic waveform.

1. What are the 4 Ps in management of HCM?

• Prevent symptoms: medical therapies with negative inotropy and chronotropy such as BB and CCB should be used. In the recent phase III EXPLORER-HCM, a cardiac myosin inhibitor, mavacamten, was shown to impressively reduce HF symptoms and LVOT gradient in patients with HoCM. In patients refractory to medical treatment, surgeries like myectomy or alcohol septal ablation are also options.
• Prevent stroke: HCM patients are at higher risk for atrial tachyarrhythmias and thus embolic stroke. All patients with atrial tachyarrhythmias should be anticoagulated regardless of their CHADSVASc score.
• Prevent sudden cardiac death (SCD) in family: HCM is an autosomal dominant genetic cardiomyopathy so all first relatives should undergo genetic testing and serial TTEs.
• Prevent SCD: HCM patients should undergo risk stratification for implantable cardiac defibrillators as VT/VF and SCD are major causes of morbidity and mortality in these patients. Some risk factors for primary prevention ICD include syncope without a clear cause, LV wall thickness > 30 mm, family history of SCD in a 1^st-degree relative, repetitive episodes of NSVT on Holter, and failure to increase SBP > 20 mmHg with exercise.

1. What’s the Brockenbrough-Braunwald-Morrow sign?

• The Brockenbrough-Braunwald-Morrow sign is a useful catheterization laboratory maneuver that describes the characteristic LV pressure tracing pattern that’s seen in dynamic LV outflow tract obstructive and can be used to differentiate obstructive HCM from other fixed valvular or subvalvular obstruction.
• Normally in patients without dynamic outflow obstruction, a compensatory pause after a PVC increases the filling time during diastole, leading to a higher stroke volume and arterial pulse pressure. Per the Frank-Starling mechanism, the expanded EDV also increases cardiac muscle stretch resulting in an increase in myocardial contractility, systolic aortic pressure, and thus an increase in pulse pressure.
• In patients with obstructive HCM, the augmented inotropic response after a PVC actually aggravates the obstruction. Thus, there is a rise in LV systolic pressure but also a rise in the LVOT gradient, resulting in a paradoxical decrease in systolic aortic pressure and pulse pressure. This is called the Brockenbrough-Braunwald-Morrow sign.

1. How do we diagnose and treat Takotsubo cardiomyopathy?

• Takotsubo cardiomyopathy leads to transient heart failure caused by severe physical or emotional stress. Most patients will recover their EF but mortality is similar to that of anterior MI. 90% of cases occur in post-menopausal women. 
• The Revised Mayo Clinic criteria, widely used to diagnose Takotsubo CM, include:
  • Transient dyskinesis of LV midsegments, with or without apical involvement
  • Regional wall motion abnormalities (WMA) extending beyond a single epicardial vascular distribution
  • Absence of obstructive coronary disease in the territory of WMA or angiographic evidence of acute plaque rupture.
  • New EKG abnormalities or modest elevation in the cardiac troponin level
  • Absence of pheochromocytoma and myocarditis
• Treatment is largely supportive and continues until the LV function recovers, usually within 21 days of onset. Anticoagulation should be started in patients with large areas of cardiac hypokinesis because major cerebral or vascular events are major complications.

References

1. Geske, J. B., Ommen, S. R., & Gersh, B. J. (2018). Hypertrophic Cardiomyopathy: Clinical Update. JACC. Heart failure, 6(5), 364–375.
2. Boyd, B., & Solh, T. (2020). Takotsubo cardiomyopathy: Review of broken heart syndrome. JAAPA : official journal of the American Academy of Physician Assistants, 33(3), 24–29.
3. Méndez, C., Soler, R., Rodríguez, E., Barriales, R., Ochoa, J. P., & Monserrat, L. (2018). Differential diagnosis of thickened myocardium: an illustrative MRI review. Insights into imaging, 9(5), 695–707.
4. Lasam G. (2018). Brockenbrough-Braunwald-Morrow Sign: An Evaluative Hemodynamic Maneuver for Left Ventricular Outflow Tract Obstruction. Cardiology research, 9(3), 180–182.
5. Cui, H., Nguyen, A., & Schaff, H. V. (2018). The Brockenbrough-Braunwald-Morrow sign. The Journal of thoracic and cardiovascular surgery, 156(4), 1614–1615.

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