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Cardiomyopathy and Myocarditis

Hypertrophic Cardiomyopathy- ESC 2008


Genetic Testing

Prevalence 1:500 on echo. 60% of these will have sarcomeric mutations. note it is not uncommon to have two mutations in the same family. Double hits are present in about 5% of probands- need to take cae with counselling and be careful to assess for all known mutations.

May find a variance in a gene but this does not definitely mean that this is disease causing.

Note with HCM mostly dealing with missense or nonsense mutations, when screening
  • do not rely on genetic testing only, clinical screening also important
  • be prepared to screen for at least five major sarcomere genes
  • note those that are genotype positive, do not know what proportion will develop phenotypic abnormality- it could be around 70% but not sure.

Imaging

About 70% have assymmetric hypertrophy and remaining have concentric or apical hypertrophy.

Septal hypertrophy patterns
  • sigmoid septum- usually in elderly- only about 8% are genotype positive
  • reverse- 79% are genotype positive
  • apical - commoner in Asians- 30% are genotype positive
  • neutral- 40% are genotype positive
  • reference: Binder J et al, Mayo Clinic Proc 2008;81:459-457
Note after surgical myectomy- if do good echo study should see colour doppler jet arising form septum into LV cavity from area of resection- this will represent the bleeding septal perforator that will often have been severed with myectomy procedure.

Risk stratification
Desai from Cleveland Clinic- see articles

HCM and pacing

AV synchronous pacing can be effective in some with LVOT obstruction by inducing dyssynchrony. But of note is that there are only three crossover randomised trials- all three found improvement of symptoms with pacing, but in 2/3 there was no objective improvement in terms of exercise time.

Pacing may well be most effective in those with a sigmoid shaped LV and not those with severe concentric LVH. These are also the same group that do not respond well to myectomy.

Clearly should not consider asymptomatic patients with no gradient.

HCM and surgery- still the gold standard

Reference- JACC 2004;44:2329-32 (have this article)

Alcohol septal ablation leads to RBBB in 30-60% of cases and risk of CHB.
With myectomy tend to get LBBB.