Spontaneous ventricular defibrillation.

SIR,-Scott et al reported that only a few patients given a permanent pacemaker subsequently needed long-term rate support.' This accords with our experience and that of other groups.2 We recently leamed, however, that what appears to be transient sinus node dysfunction may not be.3 Only one out of six patients fitted with AAI(R) pacemakers that allowed for follow-up determination of sinus node recovery time also had a normal recovery phenomenon. One patient who had been in slow junctional escape rhythm until late in the postoperative period had permanent pacemaker placement before discharge. One year later he was in sinus rhythm at a rate of about 85 beats/min and a Holter recording showed that he was overriding the pacemaker most of the day. This accorded with the findings of Scott et al and Markewitz et al.' 2 The recovery phenomenon, however, was grossly abnormal with a postpacing pause of more than 4 s during which he had symptoms.3 While it is clear that an abnormal recovery time is not in itself an indication for pacemaker placement, as we stated in our original version of our paper,3 this may not be true in a patient with a cardiac transplant who has had symptoms. Though much is known about the incidence of sinus node dysfunction after cardiac transplantation, the actual incidence of symptoms remains unknown and may be underestimated because of the low threshold for postoperative pacemaker placement. In our series of 90 patients three recipients had to be given