Limited data are available on inappropriate shocks in Korean patients implanted with an implantable cardioverter-defibrillator (ICD). We investigated the impact of inappropriate shocks on clinical outcomes. This retrospective, single-center study included 148 patients treated between October 1999 and June 2011. The primary outcome was a composite event of all-cause mortality or hospitalization for any cardiac reason. The median follow-up duration was 29 months (interquartile range: 8 to 53). One or more inappropriate shocks occurred in 34 (23.0%) patients. A history of atrial fibrillation was the only independent predictor of inappropriate shock (hazard ratio [HR]: 4.16, 95% confidence interval [CI]: 1.89-9.15, P < 0.001). Atrial fibrillation was the most common cause of inappropriate shock (67.7%), followed by supraventricular tachycardia (23.5%), and abnormal sensing (8.8%). A composite event of all-cause mortality or hospitalizations for any cardiac reason during follow-up was not significantly different between patients with or without inappropriate shock (inappropriate shock vs no inappropriate shock: 35.3% vs 35.4%, adjusted HR: 1.06, 95% CI: 0.49-2.29, P = 0.877). Inappropriate shocks do not affect clinical outcomes in patients implanted with an ICD, although the incidence of inappropriate shocks is high.
Adult ; Aged ; Atrial Fibrillation/complications ; Defibrillators, Implantable/*adverse effects ; Equipment Failure ; Female ; Hospitalization ; Humans ; Kaplan-Meier Estimate ; Male ; Middle Aged ; *Predictive Value of Tests ; Republic of Korea ; Retrospective Studies ; Risk Factors ; Shock/*etiology/mortality ; Tachycardia, Supraventricular/complications

BACKGROUND AND OBJECTIVES: It has been suggested that lead impedance measurements with using real-time telemetry may offer a good estimation of the lead system integrity, and the serial measurement of the pacing lead impedance over time is a useful tool to monitor the pacing lead performance. However, there has been no consistent data about the changes of lead impedance over time. Therefore, we investigated the correlation of the direct lead impedance and the telemetered lead impedance, and the changes of lead impedance over time in both the atrial and ventricular leads. SUBJECTS AND METHODS: The direct and telemetered lead impedances were measured at the time of the initial implantation. One-hundred and five patients (mean age: 62.5+/-13.5 years, 47 males, 47 atrial leads and 105 ventricular leads) who were without lead failure for more than 4 years since the initial implantation were included in the study. Afterwards, the telemetered lead impedance was examined at 2-month and at 12-month after implantation and then annually for 4 years in all the patients at a pacemaker clinic. RESULTS: At the initial implantation, the direct lead impedance and the telemetered lead impedance were 470.2+/-12.2omega and 540.9+/-11.6omega, respectively, in the atrial leads (r=0.72, p<0.01) and 623.7+/-14.6omega and 717.1+/-17.3omega, respectively, in the ventricular leads (r=0.82, p<0.01). In the atrial leads, the mean telemetered lead impedance rose to 583.0+/-14.0omega (p<0.01 vs baseline) at 2 months and it stabilized thereafter (p=NS). In contrast, the mean lead impedance was decreased to 653.6+/-15.6omega (p<0.01 vs baseline) at the 2-month follow-up, and then it stabilized in the ventricular leads (p=NS). CONCLUSION: There was a good correlation between the direct and telemetered lead impedance, and there was a different tendency for the change of lead impedance during the lead maturation between the atrial and ventricular leads. The telemetered lead impedance was substantially stable since the 2 months after the implantation.
Electric Impedance* ; Follow-Up Studies ; Humans ; Male ; Pacemaker, Artificial ; Telemetry

BACKGROUND AND OBJECTIVES: Tilt training as a non pharmacological therapy was recently introduced to treat the patients with neurocardiogenic syncope. Tilt training has been known to prevent neurocardiogenic syncope by desensitizing abnormal autonomic reflex. Herein, the early effect of tilt training and the preventive effect on the relapse of syncope were studied during a long-term follow-up period. SUBJECTS AND METHODS: Fifteen patients (11 males) who experienced recurrent syncope, despite drug treatment or were intolerant to drug treatment, among those diagnosed as neurocardiogenic syncope by the head-up tilt test at Samsung Medical Center between March 2000 and May 2003 were recruited. Each patient underwent tilt training after admission and was educated to continue self-tilt training after discharge. Data for recurrences after discharge were obtained via questionnaires on outpatient visits or by telephone interviews. RESULTS: Eleven (73%) of the 15 who underwent tilt training on admission showed therapeutic effects. The mean follow-up period was 21+/-10 months (5-40 months). Only one patient was excluded due to follow-up loss. Ten of the above patients underwent training by themselves for an average of 4 months after discharge, and experience no relapse of syncope during the follow-up period. CONCLUSION: Tilt training maintained its therapeutic effect during long-term follow-up. This could be a new treatment for patients non responsive or intolerant to medical therapy.
Follow-Up Studies* ; Humans ; Interviews as Topic ; Outpatients ; Recurrence ; Reflex ; Syncope ; Syncope, Vasovagal* ; Surveys and Questionnaires

BACKGROUND AND OBJECTIVES: Possible mechanisms of syncope often remain unknown despite the performance of extensive cardiological and neurological tests. An implantable loop recorder (ILR) has been introduced to monitor the heart rhythm continuously over a year. We evaluated the diagnostic value of the use of the ILR for unexplained syncope. SUBJECTS AND METHODS: Between 2006 and 2007, an ILR was implanted in 9 patients (7 male, 2 female, mean age 55+/-17 years) where syncope remained unexplained after extensive diagnostic tests. We analyzed the recorded electrocardiogram signal in the memory of the ILR. RESULTS: During a follow-up period of 8.8+/-7.3 months, arrhythmia was detected in five patients. Two patients had a sinus pause and received a permanent pacemaker, and one patient had sustained ventricular tachycardia and fibrillation and received an implantable cardioverter defibrillator. One patient had micturition syncope with sinus pause and is waiting for permanent pacemaker implantation, and one patient had symptomatic paroxysmal atrial fibrillation and was administered anticoagulation therapy. Inappropriate auto-activations such as a pseudopause or a decreasing signal were also noted. CONCLUSION: ILR monitoring seems to be a useful diagnostic tool to identify the arrhythmic cause in patients with unexplained syncope.
Arrhythmias, Cardiac ; Atrial Fibrillation ; Defibrillators ; Diagnostic Tests, Routine ; Electrocardiography ; Electrocardiography, Ambulatory ; Female ; Follow-Up Studies ; Heart ; Humans ; Male ; Memory ; Organothiophosphorus Compounds ; Syncope ; Tachycardia, Ventricular