Outcomes of single- or dual-chamber implantable cardioverter defibrillator systems in Japanese patients.
BACKGROUND
There are no criteria for selecting single- or dual-chamber implantable cardioverter defibrillators (ICDs) in patients without a pacing indication. Recent reports showed no benefit of the dual-chamber system despite its preference in the United States. As data on ICD selection and respective outcomes in Japanese patients are scarce, we investigated trends regarding single- and dual-chamber ICD usage in Japan.


METHODS
Data from a total of 205 ICD recipients with structural heart disease (median age, 63 years) in two Japanese university hospitals were reviewed. Patients with bradycardia with a pacing indication and permanent atrial fibrillation at implantation were excluded.


RESULTS
Single- and dual-chamber ICDs were implanted in 36 (18%) and 169 (82%) patients, respectively. Non-ischemic cardiomyopathy dominated both groups. Seventeen dual-chamber patients developed atrial pacing-dependency over 4.5 years, and it developed immediately after implantation in 14. Although preoperative testing showed no sign of bradycardia in these patients, their pacing rate was set higher than it was in patients who were pacing-independent (61 vs. 46 paces per min, p<0.01). Two single-chamber patients (5%) underwent atrial lead insertion. While inappropriate shock equally occurred in both groups (7 vs. 21 patients, single- vs. dual-chamber, P=0.285), device-related infection occurred only in dual-chamber patients (0 vs. 9 patients, P=0.155). No differences in death or heart failure hospitalization were observed between groups.


CONCLUSIONS
Dual-chamber ICDs were four-fold more common in Japanese patients without a pacing indication. No benefit over single-chamber ICD was observed. Newly developed atrial pacing-dependency seemed to be limited and could have been overestimated due to higher pacing rate settings in dual-chamber patients.
Department of Cardiology, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 186-8861, Japan.
Akiko
A
Ueda
Second Department of Internal Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555, Japan.
Yasushi
Y
Oginosawa
Department of Cardiology, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 186-8861, Japan.
Kyoko
K
Soejima
Department of Heart Rhythm Management, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555, Japan.
Haruhiko
H
Abe
Department of Heart Rhythm Management, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555, Japan.
Ritsuko
R
Kohno
Second Department of Internal Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555, Japan.
Hisaharu
H
Ohe
Department of Cardiology, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 186-8861, Japan.
Yuichi
Y
Momose
Department of Cardiology, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 186-8861, Japan.
Mika
M
Nagaoka
Department of Cardiology, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 186-8861, Japan.
Noriko
N
Matsushita
Department of Cardiology, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 186-8861, Japan.
Kyoko
K
Hoshida
Department of Cardiology, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 186-8861, Japan.
Yosuke
Y
Miwa
Department of Cardiology, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 186-8861, Japan.
Mutsumi
M
Miyakoshi
Department of Cardiology, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 186-8861, Japan.
Ikuko
I
Togashi
Department of Cardiology, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 186-8861, Japan.
Akiko
A
Maeda
Department of Cardiology, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 186-8861, Japan.
Toshiaki
T
Sato
Department of Cardiology, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 186-8861, Japan.
Hideaki
H
Yoshino
Dual-chamber ICD; Pacing dependency; Single-chamber ICD