What is the role of permanent pacing in hypertrophic cardiomyopathy?

There are broadly two categories of indications for permanent pacemaker insertion in patients with hypertrophic cardiomyopathy:

• • Standard indications for pacing which apply to any patient.
• • Reduction of left ventricular outflow tract gradient.

Indications for the use of dual chamber pacing with a short programmed atrioventricular delay for this purpose remain to be determined. Gradient reduction is thought to come about through a variety of effects on septal and papillary muscle motion and contractility. In general outflow gradients can be reduced by approximately 50% but the translation of this benefit into clinical improvement is variable and unpredictable. Initial enthusiasm has been tempered by equivocal results from clinical trials. A considerable placebo effect of the procedure has been observed in at least two randomised studies.1,2 Anecdotally, patients who may benefit are symptomatic elderly patients with significant left ventricular outflow tract obstruction who do not respond to conventional therapy with beta blockers, verapamil or disopyramide. The role of pacing in young patients is unclear and methods of identifying patients likely to benefit from the procedure have not been established.