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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: BACKGROUND, METHODS, RESULTS. Meshes: Aged, Aged, 80 and over, Cardiac Resynchronization Therapy, Cardiac Volume, Databases, Factual, Female, Follow-Up Studies, Heart Failure, Humans, Male, Middle Aged, Predictive Value of Tests, Retrospective Studies, Time Factors, Treatment Outcome, Ultrasonography.
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Is a reduction in total isovolumic time with cardiac resynchronisation therapy a predictor of clinical outcomes? Context: Total isovolumic time (t-IVT) reflects left ventricular (LV) asynchrony (when the ventricle is neither ejecting nor filling). It is prolonged in left bundle branch block (LBBB). Cardiac resynchronisation therapy (CRT) is a treatment for patients with heart failure, reduced LV ejection fraction and LBBB. CRT shortens t-IVT, but the long-term clinical benefit of such reduction after CRT has not been studied in this patient group. Seventy-three patients who underwent CRT had t-IVT measured before and after CRT implantation. The study end-point was a composite of unplanned heart failure hospitalisation and all-cause mortality. Baseline t-IVT showed considerable scatter: 30 patients had t-IVT values longer than 15s/min (upper 95% limit of normal). The change in t-IVT with CRT was also variable: t-IVT shortened in 50 patients (from 16.2 ± 4.8s/min to 11.7 ± 3.7s/min: group A), and lengthened in 23 patients (from 11.7 ± 4.2s/min to 14.5 ± 4.33 s/min: group B). The magnitude of change in t-IVT with CRT negatively correlated with baseline t-IVT (r=-0.619, p<0.001); thus t-IVT (significantly longer in group A than group B before CRT: 16.2 ± 4.8s/min vs. 11.7 ± 4.2s/min, p<0.001) became significantly shorter in group A compared to group B after CRT (11.7 ± 3.7s/min vs. 14.5 ± 4.3s/min, p=0.005). After follow-up of 30 months, 70% group A patients had event-free survival compared to 39% group B patients. The presence of any fall in t-IVT after CRT was an independent predictor of event-free survival.
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T-IVT is a marker of global cardiac asynchrony that has predictive capacity on functional, symptomatic, and mortality endpoints in patients with advanced heart failure. Final Decision: yes