PURPOSE: How many responders at short-term follow-up will continue to respond to cardiac resynchronization therapy (CRT) at long-term follow-up is uncertain. The aims of this study are to investigate the reversal of left ventricular mechanical dyssynchrony (LVMD) and cardiac function during long-term follow-up.
METHODS: We studied 38 consecutive patients [male 28, female 10, age 67.4± 9.5 years] on CRT. Patients with atrial fibrillation were excluded. The time difference (TPW-TDI) between the QRS onset to the end of LV ejection by pulsed wave Doppler (PW) and the QRS onset to the end of the systolic wave in basal segment with greatest delay by tissue Doppler imaging (TDI) was measured before CRT, ≤; 6 months (short-term) and > 6 months (long-term) after CRT. TPW-TDI > 50ms was defined as LVMD. A decrease of left ventricular end systolic volume ≥15% after CRT was defined as a positive response to CRT.
RESULTS: There were 18 patients with positive response to CRT and 20 patients were non responders at follow-up of 2.7± 1.8 months. Continuing follow-up of 16.7± 9.1 months, 15 (83%) of 18 responders at short-term follow-up maintained the positive response to CRT and 3 (17%) responders became nonresponders. The mean QRS duration and TPW-TDI in the initial responders were significantly reduced and LVEF had significantly improved both at short-term and long-term follow-up (p= 0.03 to p<0.0001). Of 20 CRT non-responders at short-term follow-up, 4 (20%) patients became responders at long-term follow-up. However, QRSD, TPW-TDI and LVEF in the initial nonresponders did not change significantly both at short-term and long-term follow-up (p=NS), although the mean LVEF had a trend towards improvement at long-term follow-up (p=0.06) (Table).
CONCLUSION: 17% patients with positive response to CRT at short-term follow-up will become non-responders at long-term follow-up; whereas, 20% non-responders at short-term follow-up become responders at long-term follow-up suggesting other seasons for improvement.
CLINICAL IMPLICATIONS: The study demonstrated importance in follow-up duration after CRT when we evaluate CRT response.
DISCLOSURE: Xuedong Shen, None.