Table 1

Summary Features of Patients in Included Studies

All StudiesEarly StudiesLate Studiesp Value (Early vs. Late)Available Data, n (%)
No. of studies1648678
No. of patients29,50317,04212,461
Median no. of patients per study (range)102 (9–1,164)123.5 (9–1,089)83.5 (12–1,164)0.07
Mean study duration, yrs2.5 (0–11)2.8 (0–11)2.0 (0–7)0.001
Median no. of centers (range)1 (1–128)6 (1–128)1 (1–126)0.001
% Male74.1 (72.4–75.8)74.4 (72.1–76.8)73.6 (71.2–76.1)NS (0.66)28,220 (96.6)
Age, yrs66.3 (65.3–67.3)66.7 (65.6–67.9)65.8 (64.2–67.3)NS (0.33)28,114 (96.2)
% Ischemic etiology50.3 (46.6–54.2)51.7 (46.2–57.8)48.2 (43.8–52.9)NS (0.35)25,886 (88.6)
Device upgrade procedures, %0.6 (0.4–1.1)0.4 (0.2–0.8)1.6% (0.8–3.2)0.0125,886 (88.6)
LVEF, %26 (24.5–27.7)26 (23.3–28.1)27 (24.5–28.9)NS (0.53)25,953 (88.8)
NYHA functional class2.8 (2.7–2.9)2.8 (2.6–2.9)2.9 (2.9–3.0)NS (0.06)24,326 (83.3)
QRS duration, ms155.1 (150.0–160.2)160.1 (154.4–165.8)148.9 (140.6–157.1)0.0323,240 (79.5)

Unless otherwise indicated, values are median (95% confidence interval).

LVEF = left ventricular ejection fraction; NYHA = New York Heart Association.

  • Mann-Whitney U test; other comparisons were made by using meta-regression.