RELIABILITY OF COMPUTER-AIDED HOLTER MONI TORING ANALYSIS IN DETECTING PACEMAKER DYSFUNCTIONS IN PATIENTS WITH PERMANENT VENTRICULAR INHIBITED DEMAND PACEMAKERS

The importance of the pacemaker follow-up clinic has markedly increase d in the face of the currently available multiprogrammable pacemakers. In contrast to the common standard techniques in assessing pacemaker dysfunctions, Holter monitoring allows the detection of transient pace maker dysfunctions during a long period of time. Especially computer-a ided analysis provides a considerable progress, because different pace maker dysfunctions can be detected during prolonged time periods, and - in contrast to visual analysis - a reliable survey of the real exten t of transient pacemaker dysfunctions in the individual patient is ass essed. The reliability of computer-aided analysis by a specially desig ned module was prospectively investigated in 100 consecutive patients with permanent ventricular inhibited demand pacemakers. It could be de monstrated that the positive predictive accuracy of this analysis was limited to 60.2 % in detecting failures to sense and 63.2 % in detecti ng inappropriate inhibitions, respectively. All detected failures to c apture were false positive events. The positive predictive accuracy, t herefore, was not calculated for this category of event. The overall p ositive predictive accuracy was 59.9 %. In contrast, the sensitivity o f computer-aided analysis was remarkably high. Possible causes of fals e positive and false negative findings are described. The reliability of pacemaker pulse detection was also investigated. Out of 100 analyze d Holter recordings five showed a temporary total loss of pacemaker pu lses. Loss of single pacemaker pulses was found in 30 patients. False positive pacemaker pulses were seen in three patients. These results s how that visual control and validation by an experienced Physician are mandatory. This is further emphasized by the fact that all questions exceeding the computer decision ''pacemaker dysfunction'' and its clas sification as failure to sense, inappropriate inhibition, or failure t o capture, up to now can be answered by visual control only. To date, computer-aided analysis of ECG recordings obtained from patients with VVI pacemakers is feasible. Dual-chamber pacing systems, however, can be analyzed only visually, because automatic P-wave detection in Holte r monitoring remains a problem to be solved. There are similar problem s with atrial, rate-adaptive, and antitachycardia devices because of m issing computer algorithms. In conclusion, Holter monitoring does not replace common standard techniques in investigating pacemaker function at the pacemaker follow-up clinic, but is an additional tool often us eful in detecting suspected pacemaker dysfunctions, particularly in pa tients with unexplained symptoms.