Kuznetsov VA, Soldatova AM, Krinochkin DV, Enina TN Tyumen Cardiology Research Center www.infarkta.net 625026 Tyumen, Melnikaite 111 Dynamics of left ventricular volumes and mortality in patients with early and late effect of cardiac resynchronization therapy Kuznetsov VA, Soldatova AM, Krinochkin DV, Enina TN Background Results Response to cardiac resynchronisation therapy (CRT) can be relatively «early» and «late» but the relationship between time of the best response and long-term mortality still remains unclear. Groups did not differ in clinical characteristics, NYHA functional class, QRS duration and parameters of mechanical dyssynchrony. During follow-up period (34.9±16.1 months) increase in LVEF (p=0.004) and decrease in LVESV (p<0.001) were more evident in patients with «late» response. Responders Aim To analyze the relationship between echocardiographic parameters, time of the best response and mortality in patients with congestive heart failure (CHF). Materials and methods In Kaplan-Meier analysis mortality in II group was significantly lower (3.8% vs 26.9%; p=0.001). Cox regression showed that LVESV (HR 1.014; 95% CI 1.005–1.024; p=0.002) and the time of response (HR 0.176; 95% CI 0.041–0.751 p=0.019) were associated with long-term mortality. 106 patients (83% men, III-IV NYHA), mean age 54.7 ± 9.9 years p˂0.001 At baseline, 1, 3 months and each 6 months after implantation we evaluated clinical and echocardiographic parameters The best decrease of LVESV was achieved up to 3 months I group – «early» response (1.2±0.9 months; n=26) The best decrease of LVESV was achieved after 3 months II group – «late» response (22.2±14.7 months; n=80) «late» response «early» response mortality . LVESV – left ventricular end-systolic volume. Fig. 2. Survival in patients with «early» and «late» response to CRT. Discussion According to some data one of the fundamental mechanisms of CRT is elimination of electrical dyssynchrony. It was shown that patients with wide QRS complex and the presence of left bundle branch block (LBBB) demonstrate better dynamics of clinical, functional parameters and better increase of LVEF. According to other studies the positive effects of CRT are related to the elimination of mechanical dyssynchrony parameters assessed by echocardiography. In our study patients with different time of the best response to the CRT didn’t differ in width of the QRS complex and the presence of LBBB. Also groups didn’t differ in mechanical dyssynchrony parameters. Obviously there is no single mechanism that causes the positive effect of CRT and it can be quite different in even in comparable groups. Decrease of LVESV ≥ 15% used as a standardised criteria of CRT response, however, there is still no single opinion in what observation period it should be assessed. Most studies assess echocardiographic changes during the first year after implantation. In our study 2/3 patients showed best dynamics of LVESV and LVEF in long-term period and these changes were significantly more pronounced than in patients who had the best response to the CRT during the first three months. It should be noted that 60% of responders with «late» response didn’t have positive dynamics of LVESV and LVEF during the first year of observation. The psychological aspect of our results is very important. Physicians and patients wait for a quick response to CRT and functional improvement even during the first days. It seems that fast response is associated with better reaction to CRT. Our study demonstrated association of long-term survival and time of the best response and reverse remodeling after CRT. It is important that the «early» response was associated with less clinical and functional changes and worse survival in the long term follow-up. Thus «early» clinical and functional improvement can not be used as a marker of the efficacy of CRT in the context of long-term mortality. . Conclusion Patients with «early» response to CRT show significantly lower improvement in LVEF and LVESV compared to patients with «late» CRT response. «Early» response and greater LVESV are associated with higher mortality rate.   The authors have nothing to disclose.