Exercise testing in the indication and evaluation of pacemaker treatment.

Comparison of different methods of rate responsive' pacing with expected heart rates at the same work load in normals shows that most systems have not matched rate and effort correctly. P-wave driven pacing tends to produce too fast a rate and QT-driven pacing too slow a rate for the work load. Although there are improvements compared with exercise in fixed rate pacing, these are less impressive than expected. There appears negligible benefit from AV synchrony beyond that achieved by rate increase.