Long-term mortality in patients with pauses in ventricular electrical activity.

BACKGROUND: The long-term significance of ventricular pauses of > or =3.0 seconds observed on Holter monitor is unclear, as previously conducted retrospective studies have been poorly controlled. We compared the prognosis of patients with pauses > or =3.0 seconds on Holter monitor with a well-matched control group without such pauses. METHODS: Scanning the Holter database at Ochsner Clinic (n = 11,730; January 1998 to June 2003) for pauses > or =3.0 seconds identified 70 patients (pause group). Of those, 29 (37.1%) received a permanent pacemaker (PPM group) and 41 (62.9%) did not (No-PPM group). For each No-PPM patient, two patients without pauses (<2.0 seconds) exactly matched for age, sex, ejection fraction (EF), rhythm, and duration of follow-up were randomly chosen from the Holter database (control group, n = 82) and survival of the two groups was compared. RESULTS: Mean age was 72.5 +/- 15.0 years, mean EF was 52.2 +/- 12.7%, and 68.3% were men. Mean follow-up was 2.2 years (0.5-4.5 years). There was no difference in survival between the No-PPM and the control groups (82.9% vs 84.1%, P = NS). Compared with the PPM group, pauses in the No-PPM group were more commonly asymptomatic, nocturnal, and due to sinus pauses or atrial fibrillation (AF) with slow ventricular response. CONCLUSIONS: Pauses in ventricular electrical activity > or =3 seconds on Holter monitor due to sinus pauses or AF with slow ventricular response are not predictive of heightened mortality.

Relation between left ventricular geometry and transmural dispersion of repolarization.

Studies have shown an association between left ventricular (LV) geometry and complex ventricular ectopic activity. Increased transmural dispersion of repolarization (TDR), which correlates to the interval from the peak to the end of the T wave (Tpe) on the surface electrocardiogram, is linked to ventricular tachyarrhythmias. The relation between LV geometry and TDR is unknown. The mean Tpe interval, measured from leads V(1) to V(3) of the surface electrocardiogram, was assessed in 300 patients (50% men) who had normal LV systolic function and QRS duration and were categorized into 3 equal groups, which were matched by age and gender, according to echocardiographically determined LV geometry (normal structure, concentric remodeling, and LV hypertrophy). The Tpe interval was corrected for the QT interval using Tpe/QTc and was compared among the 3 groups. Compared with those who had normal LV structure, the Tpe interval was significantly prolonged in those who had LV hypertrophy and significantly shortened in those who had concentric remodeling (p = <0.0001 for the 2 comparisons). Correcting for the QT interval using Tpe/QTc yielded similar results. Thus, TDR was increased in patients who had LV hypertrophy but decreased in concentric remodeling compared with those who had normal cardiac structure. Although LV hypertrophy represents a maladaptive geometric process that results in an unfavorable electrical substrate, concentric remodeling may represent a structural adaptation that has a more favorable electrical milieu.