Clinical Significance of Nonsustained Ventricular Tachycardia on Routine Monitoring of Pacemaker Patients.

BACKGROUND: Permanent pacemakers (PPMs) are capable of recording tachyarrhythmic events including nonsustained ventricular tachycardia (NSVT), though the clinical significance of NSVT on routine PPM evaluation is unknown. Our goals: assess the prevalence of NSVT on routine PPM follow-up and survival of PPM patients with NSVT, without NSVT, and with ventricular high rate (VHR) episodes of undefined origin. METHODS: A single-center retrospective, cohort study was performed on patients implanted with PPMs capable of recording NSVT, defined as ≥5 consecutive ventricular beats at ≥170/minutes lasting <30 seconds. Patients were categorized: (1) no NSVT; (2) NSVT; or (3) VHR episodes of uncertain etiology. The primary endpoint was all-cause mortality within 6 months of last follow-up. RESULTS: Note that in 1,125 enrollees (51.8% male, age 74.2 ± 15.5 years, ejection fraction 57.0 ± 9.0%), 742 (66%) had no NSVT, 223 had NSVT (20%), and 160 (14%) had VHR. There were no differences in ejection fraction, diabetes, hypertension, coronary disease, prior myocardial infarction, baseline creatinine, QRS duration, prevalence of left bundle branch block, or ß-blocker use among groups. "No NSVT" patients were older (P = 0.013), NSVT patients had more males (P = 0.012); atrial fibrillation and digoxin use were more prevalent in VHR patients (P < 0.01). During median follow-up of 2.8 years there were 93 deaths within 6 months of last follow-up with no differences in survival among groups (log rank P = 0.47). Age, ejection fraction at time of implant, and ß-blocker use were independent predictors of survival. CONCLUSION: NSVT detected on routine PPM follow-up in this patient population with a preserved ejection fraction is not associated with long-term mortality.

Interactive Multimodal Curriculum on Use and Interpretation of Inpatient Telemetry.

Introduction: Inpatient telemetry monitoring is a commonly used technology designed to detect and monitor life-threatening arrhythmias. However, residents are rarely educated in the proper use and interpretation of telemetry monitoring. Methods: We developed a training module containing an educational video, PowerPoint presentation, and hands-on interactive learning session with a telemetry expert. The module highlights proper use of telemetry monitoring, recognition of telemetry artifact, and interrogation of telemetry to identify clinically significant arrhythmias. Learners completed pre- and postcurriculum knowledge-based assessments and a postcurriculum survey on their experience with the module. In total, the educational curriculum had three 60-minute sessions. Results: Thirty-two residents participated in the training module. Residents scored higher on the posttest (77% ± 12%) than on the pretest (70% ± 12%), t(31) = -4.3, p < .001. Wilcoxon signed rank tests indicated PGY-3s performed better on the posttest (Mdn = 0.86) than on the pretest (Mdn = 0.72), z = -2.19, p = .031. PGY-2s also performed better on the posttest (Mdn = 0.86) than on the pretest (Mdn = 0.76), z = -2.04, p = .042. There was no difference between pretest (Mdn = 0.66) and posttest (Mdn = 0.71) scores for PGY-1s, z = -1.50, p = .142. The majority of residents reported that the telemetry curriculum boosted their self-confidence, helped prepare them to analyze telemetry on their patients, and should be a required component of the residency. Discussion: This module represents a new paradigm for teaching residents how to successfully and confidently interpret and use inpatient telemetry.

Electrocardiographic poor R-wave progression: analysis of multiple criteria reveals little usefulness.

BACKGROUND: Poor or reverse R-wave progression (PRWP) is a common statement on electrocardiogram (ECG) interpretations, but its value in diagnosing anterior myocardial infarction (MI) is disputed. We assessed the accuracy of PRWP criteria in diagnosing anterior MI. METHODS: We searched MEDLINE (1960-1998) and found 3 criteria for PRWP. We included a modified version of the Marquette Muse system's criteria and multiple novel criteria. We interpreted resting ECGs of consecutive patients undergoing pharmacologic stress tests with dual isotope gated single photon emission computed tomography. Subjects with Q-wave anterior MI, bundle branch block, or Wolf-Parkinson-White syndrome were excluded. We established whether patients met the PRWP criteria. A nuclear cardiologist blinded to PRWP classifications reviewed the scintigrams. Chi2 methods were used for statistical analysis. RESULTS: Inclusion criteria were met by 122 subjects. The standard PRWP criteria were met in 15% to 42% of ECGs. Of subjects meeting PRWP criteria, 2% to 9% had anterior MI and 27% to 33% had anterior MI or ischemia. These proportions were similar to those expected by chance. The performance of PRWP criteria did not improve when subjects with electrocardiographic left ventricular hypertrophy were excluded or when more stringent criteria for right precordial R-wave amplitude were tested. CONCLUSIONS: In our study of patients undergoing cardiac stress tests, only a small percentage of patients who met various criteria for PRWP (a proportion no different than would be expected by chance) had anterior MI. Conclusions about the presence of anterior MI solely on the basis of PRWP have little usefulness.

Does heart rate identify sudden death survivors? Assessment of heart rate, QT interval, and heart rate variability.

The objective was to test whether the circadian variability of several electrocardiographic variables distinguishes sudden cardiac death survivors from heart disease patients without a history of cardiac arrest and from normal subjects. Heart rate, heart rate variability, and QT interval have been reported to identify survivors of sudden cardiac death. Computer-assisted continuous QT measurement and heart rate variability analysis were performed on 24-hour Holter records for three groups: (1) 14 sudden death survivors; (2) 14 control patients with diagnosis and therapy matched to survivors; and (3) 14 healthy subjects. There were no significant differences in 24-hour mean RR and QT intervals between groups. However, heart rate was significantly different between the three groups at night but not during the day because the expected nighttime decline was markedly blunted in survivors and somewhat blunted in control patients. The QT interval and frequency domain heart rate variability measures followed a similar circadian pattern. The mean QTc was significantly longer in control patients. The QTc had a wide range in all groups, but less in sudden death survivors. Of ten common time and frequency domain heart rate variability indices, only SDANN and SDNN were significantly lower in sudden death survivors. Reduced circadian variation of heart rate, with marked blunting of the nighttime heart rate decline, identifies sudden cardiac death survivors as well as does SDANN and SDNN, and, in contrast to heart rate variability measures, can easily be obtained from a Holter report without complex calculations.