Rate-responsive pacing in patients with heart failure: long-term results of a randomized study.

AIMS: Chronotropic incompetence (CI) in patients with congestive heart failure (CHF) develops frequently under beta-blocker and amiodarone therapy. It can be corrected by pacing. We performed a randomized study to test whether pacing is beneficial in CHF patients with CI. METHODS AND RESULTS: Congestive heart failure patients under combined beta-blocker and amiodarone therapy (n = 77) were randomly assigned to inhibited pacing (INH; basal rate 40 bpm/hysteresis 30 bpm; n = 38) or to DDDR pacing with optimized atrioventricular delay (OPT; stimulation rate 65-120 bpm, n = 39). Groups showed similar baseline values in NYHA class, heart rate, and ejection fraction (EF) and were followed up to 10 years. The resting and mean 24 h heart rate after 1 year decreased by -2.6/-5 bpm in INH, but increased by +3.6/+6.0 bpm in the OPT group (P < 0.001). The QRS interval after 1 year increased by 12 +/- 23 ms in the INH group, but +32 +/- 36 ms in the OPT group (P < 0.01). Patients with INH developed a greater left ventricular EF (LVEF) when compared with OPT patients (+10.6 +/- 8 vs. +2 +/- 10%, respectively; P = 0.04). Changes in LVEF were negatively correlated with heart rate, but not with QRS width changes. Prognosis and the event rate were better in the INH group. CONCLUSION: In the long-term follow-up, single-site ventricular pacing in patients with CHF and low LVEF is associated with significant clinical events and a poor prognosis.

Computerized heart allograft-recipient monitoring: a multicenter study.

Computerized heart allograft recipient monitoring (CHARM) is a unique concept of patient surveillance after heart transplantation (HTx), based on the evaluation of intramyocardial electrograms (IEGMs) recorded non-invasively with telemetric pacemakers. Previous open, single-center studies had indicated a high correlation between CHARM results and clinical findings. The present study was initiated to assess the suitability of CHARM for monitoring the absence of rejection in a blind, multicenter context. During the HTx procedure, telemetric pacemakers and two epimyocardial leads were implanted in 44 patients at four European HTx centers. IEGMs during pacing were recorded and transferred via the Internet to the CHARM computer center, for automatic data processing and extraction of diagnostically relevant information, i.e., the maximum slew rate of the descending part of the repolarization phase of the ventricular evoked response (VER T-slew). The study period comprised the first 6 months after HTx, during which the transplant centers were blind to the CHARM results. A single threshold diagnosis model was prospectively defined to assess the ability of the VER T-slew to indicate clinically significant rejection, which was defined as an endomyocardial biopsy (EMB) grade greater than or equal to 2, according to the grading system of the International Society for Heart and Lung Transplantation. All EMB slides from three centers were reviewed blind by the pathologist of the fourth center in order that agreement among the histological diagnoses at the various centers could be assessed. Totals of 839 follow-ups and 366 EMBs were obtained in 44 patients. Thirty-seven patients were alive at the end of the study period. Age at HTx, EMB grade distribution, and rejection prevalence varied significantly between the centers. Review of the EMB results showed considerable differences with respect to classification of significant rejection. Comparison of average VER T-slew values with and without rejection in the 15 patients who exhibited both states revealed significantly lower values under the influence of rejection (97+/-13% vs 79+/-15%, P<0.0001). Twenty out of the 25 cases with significant rejection were correctly identified by VER T-slew values below a threshold of 98% (sensitivity =80%, specificity =50%, negative predictive value =97%, positive predictive value =11%; P<0.0005). Of the EMBs, 48% could have been saved if the diagnosis model had been used to indicate the need for EMB. A high negative predictive value for the detection of cases with significant rejection has been obtained in a prospective, blind, multicenter study. The presented method can, therefore, be used to supplement patient monitoring after HTx non-invasively, in particular to indicate the need for EMBs. In centers with patient management similar to the ones who participated in the study, this may allow a reduction in the number of surveillance EMBs.