Base over apex: does site matter for pacing the right ventricle?

Pacing for the relief of bradycardia might be considered a ‘mature’ therapy, having now been available for 50 years, so it is refreshing to see that there are still many unanswered questions relating to the practice of pacing the ventricle. Although it seems clear from population-based studies that ventricular pacing increases the risk of left ventricular dysfunction and that the cumulative percentage of pacing is directly related to that risk,1 it is unclear whether it is simply pacing the ventricle or the site of ventricular pacing that is the real problem. Perhaps, the most compelling evidence that right ventricular (RV) apical pacing may be deleterious came from the DAVID study2 which compared back-up VVI pacing at 40 ppm and DDDR pacing at 70 ppm. The VVI group did not require much ventricular pacing compared with the DDDR group. Although many patients had impaired LV function, only 12% had NYHA class III or IV symptoms and patients who were paced more frequently were more likely to have an adverse outcome in terms of heart failure. The debate about RV pacing is further confused by clinical anecdote (many patients seem to remain perfectly well despite RV apical pacing) and variable results from previous studies.3–5 These discrepancies have usually been put down to duration of pacing, differences in study design, variation in pacing site studied, and inadequate duration of …