Implantable Cardiac Monitors in Low Risk Hypertrophic Cardiomyopathy: To
Protect and Serve, or Observe and Report?
Abstract
HCM is associated with an increased risk of various cardiac arrhythmias,
including atrial fibrillation (AF), nonsustained ventricular tachycardia
(NSVT), and sustained ventricular tachycardia (VT). Furthermore, the
presence of cardiac arrhythmias has an important effect on the prognosis
of HCM patients, especially with respect to ventricular arrhythmias as a
major cause of sudden cardiac death (SCD). In this issue of Journal of
Cardiovascular Electrophysiology, Magnusson and Mörner describe the
incidence of NSVT, AF, and bradycardia in thirty patients at relatively
low risk of SCD by utilizing an implantable cardiac monitor (ICM). These
data are useful in demonstrating a fairly significant arrhythmia burden
in a low risk population. The ramifications of these findings are a bit
unclear, however. Certainly, atrial fibrillation is important to detect
in order to mitigate the increased stroke risk by instituting
anticoagulation. Detection of NSVT was less useful in this low risk
population, but could be potentially more actionable in intermediate
risk HCM patients. Thus, although further investigation is needed, the
authors have taken the first step in determining appropriate treatment
strategies for arrhythmias in HCM by helping to define the scope of the
problem.