Syncopal episodes for pregnant pt

[Nova1300]

Again, let me reiterate that a patient with asymptomatic HCM coming into a pregnancy usually will do fine. The difference is that this patient was experiencing frequent syncope prior to the pregnancy, making her higher risk for decompensating during the pregnancy.


The most common way they present is chest pain/myocardial ischemia, arrhythmia, palpitations, fatigue and dyspnea - all due to heart failure. Specifically, they tend to have LVH and resultant diastolic dysfunction. The EKG changes usually reflect these processes. In patients with worsening of their disease or a new physiologic stress, these symptoms worsen producing the higher-class NYHA symptoms. But HCM is dynamic, so these symptoms may only be temporary and a stress that provoked symptoms 2 weeks ago may not do so today.

The malignant ventricular arrhythmias are likely due to the histologic changes you spoke of. However, they also have a-fib which is probably more related to high atrial end-diastolic pressures.

Unfortunately, HCM is not a well-studied entity in this (pregnant) population.

There is a 2002 cohort study in Am. J Cardio with a very small patient population. I don't find a study of that size to be of much use, however in that study only 4% of asymptomatic patients progressed to advanced heart failure during pregnancy. 42% of those symptomatic prior to pregnancy went on to progress to NYHA 3-4 HF during pregnancy. There were no instances of malignant ventricular arrhythmia in this study. Now, these are small numbers of patients so these results must be taken with a grain of salt.

However, muscular hypertrophy is not usually the lone cause of the obstruction and resulting HF. The hypertrophy actually changes the position of the mitral valve which predisposes both to mitral dysfunction and to a phenomena known as "SAM" or systolic anterior motion in which the mitral valve's anterior leaflet flops down into the LVOT during systole which further worsens obstructive symptoms.


Overall, I think it very unlikely that this patient would make it to the end of pregnancy with no physiologic decline if we attributed her pre-existing frequent syncope to HCM.

 

[mycrofft]

No offense meant, but this is not at all what I've heard, taught, or been taught.

The textbook answer -- in my understanding -- is that while hypertrophic cardiomyopathy can present with heart failure, the most important manifestation is palpitations, syncope, and death from arrhythmia. Not so much from the structural obstruction as from the histological irregularities that predispose to abnormal conduction. Most importantly, young folks who do have syncope are exactly the ones waving a flag that they're high risk for sudden death.

But I've been wrong before and am open to correction if you have a lot of experience with peds cardiology.

Just to go farther afield, I wonder how many "healthy" young athletes' (undiagnosed) hypertrophic cardiomegaly presents initially as clinical death during physical stress?

 

[Nova1300]

Thanks to screening in families with known HCM, not too many.

 

[Brandon O]

Okay, I gotcha. I think we're on a similar page.

I know diddle about HCM in pregnancy, so I was speaking more generally. The key point being that a young person with episodes of sudden syncope, palpitations, etc (provoked by exertion, as you pointed out) should raise suspicion for HCM, along with its buddies -- WPW, Brugada, Long QT, ARVD, etc. No question than there is heart failure in these patients, but that's not what kills them... although it would unquestionably complicate a pregnancy.