In August 2003, Puglisi A et al first published the results of the Burden I trial in the European Heart Journal. This randomised study, presented some interesting findings with regards to atrial tachyarrhythmia burden in Brady-Tachy Syndrome. To accomplish this, the study compared overdrive pacing, the DDDR pacing mode and Closed Loop Stimulation (CLS).

It is widely accepted that long term RV apical pacing has detrimental effects on the myocardial function and, as a result, the clinical outlook for patients. RV apical pacing facilitates an unnatural and unfamiliar depolarisation pathway giving an electrophysiological left bundle branch block appearance on the surface ECG. It is this unusual pathway that allows for remodelling of the LV. Le Clercq et al 1 reported this remodelling as thinning of the areas of myocardium which were activated earlier than normal and a characteristic thickening of the areas which were activated later than normal. The clinical picture of such patients is one of reduced systolic function, increased hospital admissions, worsening of CHF and increased incidence of AF. It is widely accepted that haemodynamically significant intrinsic activation is the gold standard where possible in patients requiring permanent pacing.