2) Our expert author is Sergio Kaiser MD PhD FACC FESC 🇧🇷🇮🇱 @pabeda1, cardiologist 🫀, Professor 🎓 of #InternalMedicine, Rio de Janeiro State University. He brings the general cardiologist's perspective to our #HCM discussions. Read and learn!#FOAMed #CardioTwitter pic.twitter.com/bJOkEZjiZe
— cardio-met (@cardiomet_CE) April 4, 2023
4a) 1st description of #HCM in modern era was 1958. Dr Donald Teare named its obstructive phenotype “assimetrical septal hypertrophy”.
— cardio-met (@cardiomet_CE) April 4, 2023
He discussed 8 young pts; 7 died suddenly. Autopsies showed #septal #hypertrophy, disarray of muscle fibers & clefts between muscle bundles pic.twitter.com/oswmEUja0G
5a) 1964: seminal paper from #EugeneBraunwald et al ➡️ 64 pts w/ "Idiopathic hypertrophic subaortic stenosis" #IHSS, showing the dynamic nature of subaortic obstruction.
— cardio-met (@cardiomet_CE) April 4, 2023
Same article documented their initial efforts to perform #septal #myectomy pic.twitter.com/wQxa7x1DjY
6a) Called #HCM since 1979, then considered a rare inherited 🫀disease w/ almost no tx options & often ☠️⚰️.
— cardio-met (@cardiomet_CE) April 4, 2023
Now recognized as a much more common & treatable dz, often compatible with longevity and distributed worldwide.
7a) Presently, numerous tx options are available ➡️significant ⤵️in #HCM #morbidity & #mortality. However, as many pts may remain asx for a long time–even a lifetime–a high level of clinical suspicion is required.
— cardio-met (@cardiomet_CE) April 4, 2023
7c) ..assoc'd w/ 🫀 hypertrophy eg arterial #hypertension & characteristic physiologic #hypertrophy of #athlete’s 🫀. Each of these pathologies carries specific tx recs: another imp't reason to pursue correct dx.
— cardio-met (@cardiomet_CE) April 4, 2023
See @cardiomet author @IacopoOlivotto et al https://t.co/cfKunzvr4K
9) 🫀 muscle work is energy-consuming & is regulated by an active mechanism of Ca ion handling in & out of contractile proteins of the #sarcomere (basic contractile unit of the cadiomyocyte) to cyclically generate force & relaxation. This req's adenosine triphosphate #ATP.
— cardio-met (@cardiomet_CE) April 4, 2023
10b) … from where #actionpotential-triggered Ca currents are transmitted to the #sarcoplasmic reticulum & amplified along the myofibrils.
— cardio-met (@cardiomet_CE) April 4, 2023
Thin actin filaments are anchored at the Z line & form transient sliding interactions w/ thick myosin filaments. pic.twitter.com/Tbj7A3bTAY
10d)
— cardio-met (@cardiomet_CE) April 4, 2023
👉M Line (center)
👉I Band contains only #actin filaments
👉H zone contains only myosin filaments & is where sliding actin filaments from both sides approach each other
👉A band contains the mass of myosin filaments pic.twitter.com/hEpac9ghn1
11a) #Actin filaments are intertwined w/ helical protein #tropomyosin ➡️ major role in coordinating the sliding process. Actin cross-bridging sites to myosin are “hidden” by tropomyosin & can only be exposed when a “gate keeper” – the troponin complex – is activated by Ca ions.
— cardio-met (@cardiomet_CE) April 4, 2023
11c) Energy liberated from ATP hydrolysis ➡️ flexing of the myosin head & the strong binding (power stroke) to the nearest actin site. The power stroke is reversed once the resulting molecule of ADP is released and a new ATP binds to the myosin head pocket, ➡️ relaxation. pic.twitter.com/Dg7YCV2UEC
— cardio-met (@cardiomet_CE) April 4, 2023
12b) What molecule provides fuel to accomplish myocardial contraction?
— cardio-met (@cardiomet_CE) April 4, 2023
13) Welcome back! We are talking all about #HCM from the general #cardiologyperspective with expert author @pabeda1 🇧🇷🇮🇱 and you are earning LOTS of 🆓CE/#CME by following this 🧵#CardioTwitter #MedTwitter #MedEd @MedTweetorials @PreMedTweets @4hcm
— cardio-met (@cardiomet_CE) April 5, 2023
15a) So, as promised, let's move on to #HCM. What is hypertrophic cardiomyopathy? It is a primary disorder of the #myocardium, mainly characterized by unexplained #LV hypertrophy when no pressure or volume overload or no infiltrative or storage disorders can be deemed causative. pic.twitter.com/K4BU4u2GHC
— cardio-met (@cardiomet_CE) April 5, 2023
15c) Bonus pic: Anterior systolic motion of the mitral valve seen by M-mode echocardiography, leading to left ventricular outflow obstruction. Note the hypertrophied interventricular septum. pic.twitter.com/4swlwHR8vm
— cardio-met (@cardiomet_CE) April 5, 2023
17a) Alas, the clinical presentation of #HCM does not fit into a simplified vision of a monogenic inheritable disease. There is a wide range of phenotypic expressions w/o detectable mutations & also incomplete penetrance of a pathogenic mutation within the same family cluster. pic.twitter.com/16BqektTTC
— cardio-met (@cardiomet_CE) April 5, 2023
17c) Another: Variable phenotypic expression in the offspring of a ♂️w/ #HCM + for #MYBPC3 mutation. 3 of 4 siblings are also carriers. ♂️ B develops massive septal hypertrophy, ♀️ C shows limited hypertrophy, & ♀️ D has normal LV.
— cardio-met (@cardiomet_CE) April 5, 2023
🔓 https://t.co/KD31HL3mod pic.twitter.com/yBdnNsCHZt
18b) In children, the clinical expression of #HCM is much less frequent. Dx requires #LV wall thickness more than two standard deviations greater than the predicted mean (z-score 2, where a z-score is defined as the number of standard deviations from the population mean).
— cardio-met (@cardiomet_CE) April 5, 2023
19) As a general cardiologist, I see #HCM in 3⃣ hemodynamic categories: non-obstructive, obstructive, and latent-obstructive. In latent-obstructive, #LV outflow gradient <30 mmHg at rest but exceeds this threshold on exertion.
— cardio-met (@cardiomet_CE) April 5, 2023
🔓 https://t.co/t6qwNZChV7 pic.twitter.com/pHPfNaA4ZE
20b) Not infrequently, a diagnostic suspicion is raised by the finding, in an otherwise normal person, of deep, inverted symmetrical T waves on the electrocardiogram, mistakenly interpreted as myocardial ischemia
— cardio-met (@cardiomet_CE) April 5, 2023
(Figure from https://t.co/gz4EpSDOG5) pic.twitter.com/vWUhle5h8l
21b) Per guidelines, echo at rest & w/ valsalva are usu first imaging. Then Class I recommendation for #CMR if echo is inconclusive, if there is suspicion of alternative dx, or when a decision to proceed to #ICD for sudden death prevention is still uncertain.
— cardio-met (@cardiomet_CE) April 5, 2023
22a) It's essential to reassure patients & families that #HCM is treatable & is compatible w/ longevity, but periodic reassessment is req'd ad infinitum. Its evolution is not uniform & there are different pathways it can follow, from no progression at all to significant dis.
— cardio-met (@cardiomet_CE) April 5, 2023
22c) #HCM exerts its most significant clinical effect in midlife:
— cardio-met (@cardiomet_CE) April 5, 2023
🫀 avg age 1st #ICD to prevent #SCD = 45
🫀 first #mymectomy for #HF = 52
🫀 onset of #AFib = 54,
per 🔓https://t.co/5bTlrFAdfG
23) Thanks to advances in risk stratification, medical and interventional therapy for #HCM, mortality has sharply ⬇️from 3 – 6% per year in early referral cohorts ➡️ only 0.5% per year in contemporary referral cohorts
— cardio-met (@cardiomet_CE) April 5, 2023
🔓https://t.co/5bTlrFAdfG pic.twitter.com/IEaTo8ZN9J
24b) When LGE occupies >15% of the LV wall, adverse remodeling ensues and the risk of sudden death increases two-fold. See 🔓https://t.co/rgh7QQ4Zkh pic.twitter.com/Invh0Nu9uz
— cardio-met (@cardiomet_CE) April 5, 2023
24d) Here are potential risk factors for sudden death according to ACC/AHA guidelines (🔓 https://t.co/Rjq6llrI2r): pic.twitter.com/pq5nQFqPTq
— cardio-met (@cardiomet_CE) April 5, 2023
25b) New approaches to tx #LVOTO–surgical #myectomy & alcohol septal #ablation were introduced and addressed many sx, while #SCD episodes were largely ⬇️ after introduction of #ICD’s.
— cardio-met (@cardiomet_CE) April 5, 2023
25d) Meanwhile, 2020 ACC/AHA #guidelines for classical pharmacological therapy of patients with #oHCM are summarized here:
— cardio-met (@cardiomet_CE) April 5, 2023
🔓 https://t.co/Rjq6llrI2r pic.twitter.com/Ry4TWsTXsz
25f) Notably, there are no recommendations for pharmacological treatment in asymptomatic patients with proven non-obstructive #HCM.
— cardio-met (@cardiomet_CE) April 5, 2023
26b) Among those w/ #LVSD, sig predictors of composite all-cause death, cardiac transplantation & #LVAD implantation were
— cardio-met (@cardiomet_CE) April 5, 2023
🫀multiple pathogenic/likely pathogenic sarcomeric variants: HR 5.6 [95% CI, 2.3–13.5]
🫀 #Afib: HR 2.6 [1.7–3.5]
🫀 #LVEF < 35% HR 2.0 [1.3–2.8]
26d) 1/4 pts dev'd #AFib. Recently, ablation techniques & septal myectomy+/- #Cox_Maze surgery ➡️ 50% ⬇️in recurrent episodes over the short term (https://t.co/Wfsw7DOz2O).
— cardio-met (@cardiomet_CE) April 5, 2023
🫀 BTW, mortality attrib'd to #AF in contemp cohorts of #HCM pts is <1%/y (🔓https://t.co/08ECus0FQJ).
27b) In such centers, myectomy ➡️survival benefit w/ 99%, 98%, & 95% free from HCM-related mortality at 1, 5, & 10 yrs, respectively. See 🔓https://t.co/ZTXl5LDj2l. Lower-volume centers don't perform as well: 🔓https://t.co/a79uv9Od1z pic.twitter.com/gNFNwP0BFy
— cardio-met (@cardiomet_CE) April 5, 2023
29) Which of the following is NOT a #riskfactor for #SCD in a patient with #HCM?
— cardio-met (@cardiomet_CE) April 5, 2023
a. unexplained recent syncope
b. recent acute coronary syndrome
c. diffuse and extensive late gadolinium enhancement
d. LV apical aneurysm
Mark your answer!
31) For now, you have earned 0.75h 🆓CE/#CME and you can claim it with a few clicks of the 🖱️at https://t.co/Z0rBgtukng. I am @pabeda1 and I hope you'll join me next week for Part 2 of this tweetorial!
— cardio-met (@cardiomet_CE) April 5, 2023