Survival in second degree atrioventricular block

Sir, The important paper by Shaw et al (1985;53: 587-93) showed that elderly patients with persistent type I second degree heart block have a poor prognosis. They concluded that in the absence of special circumstances these patients should receive permanent pacemakers. Indications for pacemaker implantation have changed and we need to consider the findings of Shaw et al in the light of current practice. Thirty of their 77 patients with type I block survived to develop complete heart block and in many centres would have received pacemakers. Thirty five patients had experienced Adams-Stokes attacks during follow up; however, only 33 patients received pacemakers, in 29 cases for disturbance of consciousness or other major cardiac symptoms. Thus as many as 13 of 77 patients remained without pacemakers despite having symptoms of disturbed consciousness that may have been bradycardia related. Furthermore, at entry 25% of patients had cardiac dyspnoea and 23% had angina, both symptoms that may have reflected inadequate chronotropic responses to exercise and might be amenable to modem pacemaker treatment. Before advising permanent pacemaker implantation in these patients we need to be reassured that their sudden deaths were more likely to have been caused by progression of conduction disorder than from other causes. Serious concurrent medical conditions in their group I patients included previous myocardial infarction (16%), rheumatic fever (12%), diabetes mellitus (6%), stroke (12%), and rheumatoid arthritis (13%). Was the favourable outcome in paced group I patients the result of pacing or freedom from other medical conditions? Shaw and colleagues have demonstrated that in some patients type I heart block is a predictor of progressive conduction disorder. These patients require careful evaluation and follow up, which will certainly involve ambulatory monitoring and possibly evaluation of chronotropic responses to exercise. This valuable study has led us to change our views on the management of these patients but has not yet convinced us that they should all receive pacemakers at presentation.