Implementation of seven echocardiographic parameters of myocardial asynchrony to improve the long-term response rate of cardiac resynchronization therapy (CRT)

<p>Abstract</p> <p>Background</p> <p>Cardiac resynchronization Therapy (CRT) is an effective therapy for chronic heart failure with beneficial hemodynamic effects leading to a reduction of morbidity and mortality. The responder rates, however, are low. There are various and contentious echocardiographic parameters of myocardial asynchrony. Patient selection by echocardiographic assessment of asynchrony is thought to improve responder rates.</p> <p>Methods</p> <p>In this small single-center pilot-study, seven established parameters of myocardial asynchrony were used to select patients for CRT: (1) interventricular electromechanical delay (IMD, cut-off ≥ 40 ms), (2) Septal-to-posterior wall motion delay (SPWMD, ≥ 130 ms), (3) maximal difference in time-to-peak velocities between any two of twelve LV segments (Ts-12 ≥ 104 ms), (4) standard deviation of time to peak myocardial velocities (Ts-12-SD, ≥ 34.4 ms), (5) difference between the septal and basal time-to-peak velocity (TDId, ≥ 60 ms), (6) left ventricular electromechanical delay (LVEMD, > 140 ms) and (7) delayed longitudinal contraction (DLC, > 2 segments).</p> <p>16 chronic heart failure patients (NYHA III–IV, LVEF < 0.35, QRS ≥ 120 ms) at least two out of seven parameters of myocardial asynchrony received cardiac resynchronization therapy (CRT-ICD). Follow-up echo examination was after 6 months. The control group was a historic group of CRT patients (n = 38) who had not been screened for echocardiographic signs of myocardial asynchrony prior to device implantation.</p> <p>Results</p> <p>Based on reverse remodeling (relative reduction of LVESV > 15%, relative increase of LVEF > 25%), the responder rate to CRT was 81.2% in patients selected for CRT according to our protocol as compared to 47.4% in the control group (p = 0.04). At baseline, there were on average 4.1 ± 1.6 positive parameters of asynchrony (follow-up: 3.7 [± 1.6] parameters positive, p = 0.52). Only the LVEMD decreased significantly after CRT (p = 0.027). The remaining parameters showed a non-significant trend towards reduction of myocardial asynchrony.</p> <p>Conclusion</p> <p>The implementation of different markers of asynchrony in the selection process for CRT improves the hemodynamic response rate to CRT.</p

Echocardiography of the right heart

Echocardiography allows for accurate measurements of pulmonary vascular resistance and hydraulic load, and thus the estimation of afterload in severe pulmonary hypertension as a cause of right ventricular (RV) failure. The procedure also provides a series of estimates of RV systolic function, such as fractional area change, tricuspid annular plane excursion, tricuspid annulus tissue Doppler imaging of the velocities of isovolumic contraction and ejection, strain and strain rate. These indices help to evaluate the adequacy of RV systolic function adaptation to afterload (Anrep mechanism) but suffer from variable degrees of preload-dependency. Failure of RV-arterial coupling results in Starling's mechanism of preservation of stroke volume through increased myocardial fibre length, or end-diastolic volume. This can be appreciated by echocardiographic measurements of increased right heart chamber dimensions, dilatation and loss of inspiratory collapsibility of the inferior vena cava, and pericardial effusion, along with altered indices of left ventricular diastolic function such as prolonged isovolumic relaxation time, deceleration of E waves, and decreased ratio of E over A waves. Echocardiographic dimension measurements are currently limited to a series of planes, with difficult instantaneous volume reconstruction of the RV, which has an irregular crescent shape and inhomogenous contraction. Echocardiography is limited by operator-dependency, and is sometimes implemented in low clinical probability contexts. This may be a cause of false positive or negative diagnosis of RV failure. Recent advances in echocardiography technology open the perspective of RV volume measurements with assessment of regional function and asynchrony.SCOPUS: ch.binfo:eu-repo/semantics/publishe