BACKGROUND: The effects of cardiac resynchronization therapy (CRT) in patients with mildly symptomatic heart failure have not been fully elucidated. METHODS AND RESULTS: The Multicenter InSync ICD Randomized Clinical Evaluation II (MIRACLE ICD II) was a randomized, double-blind, parallel-controlled clinical trial of CRT in NYHA class II heart failure patients on optimal medical therapy with a left ventricular (LV) ejection fraction < or =35%, a QRS > or =130 ms, and a class I indication for an ICD. One hundred eighty-six patients were randomized: 101 to the control group (ICD activated, CRT off) and 85 to the CRT group (ICD activated, CRT on). End points included peak VO2, VE/CO2, NYHA class, quality of life, 6-minute walk distance, LV volumes and ejection fraction, and composite clinical response. Compared with the control group at 6 months, no significant improvement was noted in peak VO2, yet there were significant improvements in ventricular remodeling indexes, specifically LV diastolic and systolic volumes (P=0.04 and P=0.01, respectively), and LV ejection fraction (P=0.02). CRT patients showed statistically significant improvement in VE/CO2 (P=0.01), NYHA class (P=0.05), and clinical composite response (P=0.01). No significant differences were noted in 6-minute walk distance or quality of life scores. CONCLUSIONS: In patients with mild heart failure symptoms on optimal medical therapy with a wide QRS complex and an ICD indication, CRT did not alter exercise capacity but did result in significant improvement in cardiac structure and function and composite clinical response over 6 months.
RCT Entities:
BACKGROUND: The effects of cardiac resynchronization therapy (CRT) in patients with mildly symptomatic heart failure have not been fully elucidated. METHODS AND RESULTS: The Multicenter InSync ICD Randomized Clinical Evaluation II (MIRACLE ICD II) was a randomized, double-blind, parallel-controlled clinical trial of CRT in NYHA class II heart failurepatients on optimal medical therapy with a left ventricular (LV) ejection fraction < or =35%, a QRS > or =130 ms, and a class I indication for an ICD. One hundred eighty-six patients were randomized: 101 to the control group (ICD activated, CRT off) and 85 to the CRT group (ICD activated, CRT on). End points included peak VO2, VE/CO2, NYHA class, quality of life, 6-minute walk distance, LV volumes and ejection fraction, and composite clinical response. Compared with the control group at 6 months, no significant improvement was noted in peak VO2, yet there were significant improvements in ventricular remodeling indexes, specifically LV diastolic and systolic volumes (P=0.04 and P=0.01, respectively), and LV ejection fraction (P=0.02). CRT patients showed statistically significant improvement in VE/CO2 (P=0.01), NYHA class (P=0.05), and clinical composite response (P=0.01). No significant differences were noted in 6-minute walk distance or quality of life scores. CONCLUSIONS: In patients with mild heart failure symptoms on optimal medical therapy with a wide QRS complex and an ICD indication, CRT did not alter exercise capacity but did result in significant improvement in cardiac structure and function and composite clinical response over 6 months.
Authors: Thomas Berger; Ralf Harun Zwick; Markus Stuehlinger; Wolfgang Dichtl; Gerhard Poelzl; Michael Edlinger; Otmar Pachinger; Florian Hintringer Journal: Clin Res Cardiol Date: 2010-09-23 Impact factor: 5.460
Authors: Steven A Lubitz; Peter Leong-Sit; Nowell Fine; Daniel B Kramer; Jagmeet Singh; Patrick T Ellinor Journal: Eur J Heart Fail Date: 2010-04 Impact factor: 15.534
Authors: George Wells; Ratika Parkash; Jeffrey S Healey; Mario Talajic; J Malcolm Arnold; Shannon Sullivan; Joan Peterson; Elizabeth Yetisir; Patricia Theoret-Patrick; Marilynn Luce; Anthony S L Tang Journal: CMAJ Date: 2011-01-31 Impact factor: 8.262