Hypertrophic Cardiomyopa...
Highlights
- Hypertrophic cardiomyopathy is one of the most common causes of Sudden Cardiac Arrest in young adults. What is #HCM exactly?
A 🧵 on Hypertrophic Cardiomyopathy...1/24
We'll cover:
- Dx criteria
- Pathophys
- Prevalence
- Natural hx & Clinical clues
- Management & NEW Tx
(View Tweet)
- First, what is #HCM?
Clinically diagnosed: unexplained LVH
➡️ Not accounted by pressure overload: HTN, aortic stenosis
➡️ Not accounted by infiltration: amyloid or Fabry’s
By ECHO in adults:
➡️ Ventricular wall ≥15 mm in absence of other dx
➡️ Family hx of HCM: wall ≥13 mm
/2 (View Tweet)
- What is the pathophys of HCM?
- Pathogenic variants in sarcomere gene
- 75% of “+ve genetic testing” have mutations:
➡️ Myosin binding protein C (MYBPC3)
➡️ Myosin binding heavy chain (MYH7)
📌 Mutations ⬆️ force & ⬇️ sarcomere relaxation
❓ 50% no identified genetic cause
/3
(View Tweet)
- Moving on to Prevalence.
What is the population estimate of hypertrophic cardiomyopathy prevalence?
/4 (View Tweet)
- Answer: The estimate is 1:500. Around 600,000 cases in the US.
🚨 HCM is the most common monogenic heart disease
How about symptoms to look out for?
- Exertional dyspnea
- Angina
- Palpitations
- Orthopnea/PND
- Syncope or presyncope (esp in pts w/ LVOT obstruction)
/5 (View Tweet)
- How about physical exam findings?
- Systolic murmur LSB
- Radiates to RUSB & apex
- Murmur intensify w/ ⬇️ preload (Valsalva, squat-to-stand; see @BradLander18 @mmartinezheart @ACCinTouch
- Murmur soften w/ ⬆️ afterload (passive ⬆️ LE, clench fists)
/6
https://t.co/GoBU9PiEM8 (View Tweet)
- What is the natural history of HCM?
➡️ Most are asymptomatic (~60%)
➡️ Cumulative burden: those dx earlier, ⬆️ events
🚨 Most common dx burden:🫀Failure & Afib
➡️ LVOT: systolic anterior motion of MV & MR
🔑 Outcomes most prevalent after 50y
/7
(View Tweet)
- What EF defines LV w/ systolic dysfunction or “burned-out” phase in HCM?
/8 (View Tweet)
- Answer: <50%
HCM is normally associated w/ a hyperdynamic LV...so when EF <50%, end-stage HCM has a poor prognosis. Prevalence ~8%.
Natural history of "burned-out" HCM:
🚨 75% experienced adverse event
☠️ 35% death/transplant/LVAD
➡️ At median time 8.4 yrs from recognition
/9
(View Tweet)
- Moving on to types of HCM:
- Non-obstructive HCM (nHCM) ~1/3 of pts
- Obstructive HCM (oHCM) ~2/3 of pts
➡️ gradients at rest or exercise >30 mmHg
This is an important distinction as this will guide management discussed later.
/10 (View Tweet)
- What imaging/tests to order to distinguish nHCM & oHCM?
➡️ Exercise ECHO: provokable gradients
➡️ CMR: identify SAM, LVOT
➡️ LHC: +ve Brockenborough-Braunwald-Morrow sign (1961)
+ve sign: s/p PVC induction⚡️, LV SBP ⬆️ & aortic pulse pressure ⬇️ (see below Fig 2 vs in AS)
/11
(View Tweet)
- Moving on to management.
Symptoms drive management.
No symptoms? No need for therapy.
For patients with oHCM and symptoms, what is the first line treatment?
/12 (View Tweet)
- A: Metoprolol
2020 ACC/AHA Guidelines (oHCM + symp):
✅ BB 1st-line
✅ Non-dihydropyrid CCBs (if ineffective)
✅ Disopyramide or SRT (symp persist)
Optimize pre + after-load:
⚠️ Cautious w/ diuretics
⛔️ Avoid vasodilators
❗️ Treat tachycardia
✅ IV phenylephrine for acute hypo
(View Tweet)
- Moving on to invasive treatment of symptomatic patients w/ oHCM.
What are the indications for septal reduction therapy? /14 (View Tweet)
- A: Both.
Symptoms impair QoL despite medical therapy.
Usually NYHA functional class III or IV.
2 options:
1⃣ Surgical Myectomy
2⃣ Septal Ablation
Choice depends:
➡️ suitable coronary anatomy (septal perf. artery for ablation)
➡️ extensive LVH or MV dx (favors myectomy)
/15 (View Tweet)
- How about for patients with end-stage non-obstructive HCM (nHCM)?
A pt w. nHCM + afib p/w volume overload. LVEF <50%.
What changes in management are you considering? /16 (View Tweet)
- A:
✅ Anticoagulation for ALL HCM pts w/ afib
✅ Consider GDMT (ARNi/ACEi/ARB, MRA)
🚫 Stop -ve inotropic agents (verapamil, diltiazem, disopyramide) unless for rate-control AF
✅ Consider ICD for primary prevention
⚠️ RCTs excluded HCM & HF pts; consider on a case-by-case /17 (View Tweet)
- Moving on to risk stratification for sudden cardiac death.
Which HCM patient below should be considered for an ICD? /18 (View Tweet)
- Answer: All of the above.
All are Class 2A recommendations ("ICD is reasonable") from the ACC/AHA 2020 HCM Guidelines.
If patient has had a prior event (SCD, VF, Sustained VT)
✅ Class 1: ICD recommended
/19
(View Tweet)
- How about family screening and genetic testing?
A 35 yo man is diagnosed with genetic HCM. You recommend genetic testing and surveillance for his 12 yo son. How often should his son receive surveillance screening? /20 (View Tweet)
- Answer: Every 1-2 yrs
There is an age-dependent penetrance to HCM. Serial screening is required:
✅ Physical exam
✅ ECHO
✅ ECG
The younger the age of diagnosis, the more frequent the surveillance for 1st degree relatives.
For pt's 50 yo sister. Surveillance every 3-5 yrs
(View Tweet)
- How about sports & exercising with HCM?
✅ Mild-mod intensity recreational exercise is recommended
Recently (May 2023), LIVE-HCM Study @JAMACardio showed vigorous exercise in pts w/ HCM did not ⬆️ mortality or ⬆️ incidence of ventric. arrhythmias
Shared decision w/ pts 🔑
/22
(View Tweet)
- Finally, how about disease-modifying therapy?
In April 2022, @US_FDA approved the only current therapy for symptomatic oHCM:
✅ Mavacamtem: cardiac myosin inhibitor
Dr. Braunwald 1st described "hypertrophic subaortic stenosis” in 1964, elaborates here: https://t.co/AD7aP6L93j (View Tweet)
- The approval was based on:
EXPLORER-HCM:
➡️ Mavacamten vs placebo ⬆️ exercise capacity & health status in oHCM (LVOT>50 mmHg)
VALOR-HCM:
➡️ Mavacamten ⬇️ eligibity for needing SRT vs placebo among oHCM (considering SRT + on max tx)
Aficamten (another CMI) is promising...
/24
(View Tweet)
- 🚨 Takeaways 🚨
📌 Key diagnostic feature: unexplained LVH
📌 Mgmt for symptoms depends on pathophys (oHCM, nHCM, restrictive, LVSD)
📌 Importance of family surveillance + genetic testing
📌NEW + other exciting disease-modifying txs to come...
/Fin (View Tweet)
- That was a lot. Thanks for following along!
And thank you to everyone who has played a part in revolutionizing/raising awareness on #HCM
@MasriAhmad @MKIttlesonMD @srihariNaiduMD @ReshadGaranMD @UTahirMD @MJAckermanMDPhD @MartinMaronMD @LindenfeldJoann (View Tweet)
- My main source in addition to links in thread:
https://t.co/wW4VjNSyJ4
@YevgeniyBr @HanCardiomd @AHajduczok @akhadilkarMD @DrJohnMcP @VUMCMedicineRes @vumccardsfit @HollyGHeartMed (View Tweet)