Different response rates to cardiac resynchronization therapy (CRT) according to the applied definition.

BACKGROUND Solid evidence shows that cardiac resynchronization therapy (CRT) improves prognosis, physical capacity and quality of life in selected groups of patients with chronic heart failure (CHF). Nonetheless, marked percentage of patients seem not to benefit from CRT. MATERIAL AND METHODS Sixty consecutive patients (aged 66.3 +/- 8.7 years, 57 men - 95%, 3 women - 5%) with CHF (71.7% with ischaemic and 28,3% with non-ischaemic origin) of stable for > or = 3 months NYHA III or IV class despite optimized pharmacotherapy, with left ventricle end-diastolic diameter (LVEDd) > or = 55 mm, left ventricular ejection fraction (EF) < or = 35% and QRS > 130 ms were evaluated before and 3 months after CRT implementation (biventricular stimulation BiV) echocardiographically and clinically. RESULTS EF increased (21.7% vs 26,6%, p<0,0001), 6-minute walk distance (6-MWT) rose (298.0 m vs 373.1 m, p<0,0001), left ventricular end-diastolic volume (LVEDV) and left ventricular end-systolic volume (LVESV) decreased (244.3 ml vs 226,4 ml, p=0.0002; 192.8 ml vs 168,7 ml, p<0,0001 respectively). Mean NYHA class dropped from 3.1 to 2.2 (p<0.0001). Absolute increase in EF of > or = 4%, > or = 5%, > or = 6% was observed in 63.2%, 52.6%, and 35.7% respectively; relative increase of > or = 25% presented 21.1%, > or = 10% reduction of LVESV--59.7%, > or = 15% reduction of LVESV--43.8%, decrease in NYHA class--78.3%, > or = 10% reduction of 6-MWT--66.7%, no death and no hospitalization due to heart failure--78.3%. CONCLUSIONS Response to CRT rate differs markedly according to the applied definition.