Automatic optimization of resting and exercise atrioventricular interval using a peak endocardial acceleration sensor: validation with Doppler echocardiography and direct cardiac output measurements

Assessment of Myocardial Contractility by SonR Sensor in Patients Undergoing Cardiac Resynchronization Therapy

BACKGROUND

SonR sensor signal correlates well with myocardial contractility expressed in terms of left ventricular (LV) dP/dt max. The aim of our study was to evaluate the changes in myocardial contractility during isometric effort in heart failure patients undergoing cardiac resynchronization therapy (CRT) with right atrial SonR sensor.

METHODS

Thirty-one patients (19 men, 65 ± 7 years, LV ejection fraction [LVEF] 28% ± 5%, in sinus rhythm) were implanted with a CRT-defibrillator (CRT-D) device equipped with SonR sensor, which was programmed in VVI mode at 40 beats/min. Twenty-four hours after implantation, each patient underwent a noninvasive hemodynamic evaluation at rest and during isometric effort, including: (1) measurement of beat-to-beat endocavitary SonR signal; (2) echocardiographic assessment; and (3) continuous measurement of blood pressure with Nexfin method (BMEYE, Amsterdam, the Netherlands). The following contractility parameters were considered: (1) mean value of beat-to-beat SonR signal; (2) mean value of LV dP/dt by Nexfin system; and (3) fractional shortening (FS) by echocardiography.

RESULTS

At the third minute of the isometric effort, mean value of SonR signal significantly increased from baseline (P < 0.001). Similarly, mean value of both LV dP/dt by Nexfin and FS significantly increased compared to the resting condition (P < 0.001; P < 0.001). While in 27 (88%) patients SonR signal increased at the third minute of the isometric effort, in four (12%) patients SonR signal decreased. In these patients, both LV dP/dt by Nexfin and FS consensually decreased.

CONCLUSIONS

In CRT patients, SonR sensor is able to detect changes in myocardial contractility in a consensual way like noninvasive methods such as Nexfin system and echocardiography.

First clinical evaluation of an atrial haemodynamic sensor lead for automatic optimization of cardiac resynchronization therapy

AIMS

One option to improve cardiac resynchronization therapy (CRT) responder rates lies in the optimization of pacing intervals. A haemodynamic sensor embedded in the SonRtip atrial lead measures cardiac contractility and provides a systematic automatic atrioventricular and interventricular delays optimization. This multi-centre study evaluated the safety and performance of the lead, up to 1 year.

METHODS AND RESULTS

A total of 99 patients were implanted with the system composed of the lead and a CRT-Defibrillator device. Patients were followed at 1, 3, 6, and 12 months post-implant. The primary safety objective was to demonstrate that the atrial lead complication free rate was superior to 90% at 3-months follow-up visit. A lead handling questionnaire was filled by implanting investigators. Lead electrical performances and the performance of the system to compute AV and VV delays were evaluated at each study visit over 1 year. The complication free rate at 3 months post-implant was 99.0% [95%CI 94.5-100.0%], P < 0.001. Electrical performances of the lead were adequate whatever the atrial lead position and remained stable over the study period. The optimization algorithm was able to compute AV and VV delays in 97% of patients, during >75% of the weeks.

CONCLUSION

The atrial lead is safe to implant and shows stable electrical performance over time. It therefore offers a promising tool for automatic CRT optimization to further improve responder rates to CRT.

Automatic optimization of cardiac resynchronization therapy using SonR-rationale and design of the clinical trial of the SonRtip lead and automatic AV-VV optimization algorithm in the paradym RF SonR CRT-D (RESPOND CRT) trial

Although cardiac resynchronization therapy (CRT) is effective in most patients with heart failure (HF) and ventricular dyssynchrony, a significant minority of patients (approximately 30%) are non-responders. Optimal atrioventricular and interventricular delays often change over time and reprogramming these intervals might increase CRT effectiveness. The SonR algorithm automatically optimizes atrioventricular and interventricular intervals each week using an accelerometer to measure change in the SonR signal, which was shown previously to correlate with hemodynamic improvement (left ventricular [LV] dP/dtmax). The RESPOND CRT trial will evaluate the effectiveness and safety of the SonR optimization system in patients with HF New York Heart Association class III or ambulatory IV eligible for a CRT-D device. Enrolled patients will be randomized in a 2:1 ratio to either SonR CRT optimization or to a control arm employing echocardiographic optimization. All patients will be followed for at least 24 months in a double-blinded fashion. The primary effectiveness end point will be evaluated for non-inferiority, with a nested test of superiority, based on the proportion of responders (defined as alive, free from HF-related events, with improvements in New York Heart Association class or improvement in Kansas City Cardiomyopathy Questionnaire quality of life score) at 12 months. The required sample size is 876 patients. The two primary safety end points are acute and chronic SonR lead-related complication rates, respectively. Secondary end points include proportion of patients free from death or HF hospitalization, proportion of patients worsened, and lead electrical performance, assessed at 12 months. The RESPOND CRT trial will also examine associated reverse remodeling at 1 year.

Heart failure monitoring with a cardiac resynchronization therapy device-based cardiac contractility sensor: a case series

Introduction

The SonR signal has been shown to reflect cardiac contractility. It is recorded with an atrial lead connected to a cardiac resynchronization therapy defibrillator. For the first time, clinical evidence on the use of the SonR signal in the monitoring of the clinical status of heart failure patients implanted with cardiac resynchronization therapy defibrillator are presented through three clinical cases.

Case presentation

In the two first patients (non-Hispanic/Latino white), the SonR amplitude increases concomitantly to clinical status improvement subsequent to cardiac resynchronization therapy defibrillator implantation. In the third patient (non-Hispanic/Latino white), a decrease in SonR amplitude is observed concomitantly to atrial fibrillation and clinical status deterioration.

Conclusions

This case series reports the association between SonR signal amplitude changes and patients’ clinical status. Combined with remote monitoring, early SonR signal amplitude remote monitoring could be a promising tool for heart failure patients’ management.

A randomized pilot study of optimization of cardiac resynchronization therapy in sinus rhythm patients using a peak endocardial acceleration sensor vs. standard methods

AIMS

Non-response rate to cardiac resynchronization therapy (CRT) might be decreased by optimizing device programming. The Clinical Evaluation on Advanced Resynchronization (CLEAR) study aimed to assess the effects of CRT with automatically optimized atrioventricular (AV) and interventricular (VV) delays, based on a Peak Endocardial Acceleration (PEA) signal system.

METHODS AND RESULTS

This multicentre, single-blind study randomized patients in a 1 : 1 ratio to CRT optimized either automatically by the PEA-based system, or according to centres' usual practices, mostly by echocardiography. Patients had heart failure (HF) New York Heart Association (NYHA) functional class III/IV, left ventricular ejection fraction (LVEF) <35%, QRS duration >150 or >120 ms with mechanical dyssynchrony. Follow-up was 1 year. The primary endpoint was the proportion of patients who improved their condition at 1 year, based on a composite of all-cause death, HF hospitalizations, NYHA class, and quality of life. In all, 268 patients in sinus rhythm (63% men; mean age: 73.1 ± 9.9 years; mean NYHA: 3.0 ± 0.3; mean LVEF: 27.1 ± 8.1%; and mean QRS duration: 160.1 ± 22.0 ms) were included and 238 patients were randomized, 123 to PEA and 115 to the control group. At 1 year, 76% of patients assigned to PEA were classified as improved, vs. 62% in the control group (P= 0.0285). The percentage of patients with improved NYHA class was significantly (P= 0.0020) higher in the PEA group than in controls. Fatal and non-fatal adverse events were evenly distributed between the groups.

CONCLUSION

PEA-based optimization of CRT in HF patients significantly increased the proportion of patients who improved with therapy, mainly through improved NYHA class, after 1 year of follow-up.

Atrioventricular and interventricular delay optimization in cardiac resynchronization therapy: physiological principles and overview of available methods

In this review, the physiological rationale for atrioventricular and interventricular delay optimization of cardiac resynchronization therapy is discussed including the influence of exercise and long-term cardiac resynchronization therapy. The broad spectrum of both invasive and non-invasive optimization methods is reviewed with critical appraisal of the literature. Although the spectrum of both invasive and non-invasive optimization methods is broad, no single method can be recommend for standard practice as large-scale studies using hard endpoints are lacking. Current efforts mainly investigate optimization during resting conditions; however, there is a need to develop automated algorithms to implement dynamic optimization in order to adapt to physiological alterations during exercise and after anatomical remodeling.

[New technologies in the optimization of CRT programming]

After implanting a CRT device, consistent and scheduled patient follow-up is mandatory. Besides determining electrode parameters and reviewing arrhythmic episodes, these follow-ups focus on monitoring and optimizing congestive heart failure therapy. Therefore new CRT devices present methods for heart failure surveillance and telemetric transmission of the acquired data, which allows the physician to respond immediately to the varying needs of the respective heart failure patient. In addition to cardiac resynchronization, optimization of atrioventricular (AV) and interventricular (VV) delay provide major hemodynamic benefits. As echocardiographic optimization of AV and VV delay is time consuming it is often not feasible during daily clinical practice. Therefore implemented algorithms that automatically determine and adapt AV and VV delays with respect to the fluctuating needs of the patients are essential. This article presents the current state of monitoring and optimization methods in CRT devices.

Advances in devices for cardiac resynchronization in heart failure

Patients with advanced heart failure have a high mortality and morbidity despite medical therapy. Depending on the underlying heart disease and severity of heart failure, 3.7 to 52.8% of patients have a QRS complex > or =120 ms who may have interventricular and intraventricular dyssynchrony correctible by cardiac resynchronization therapy (CRT). The latter is usually achieved with biventricular pacing, with the left ventricular lead placed in a tributary of the coronary sinus (CS), with a reported success rate between 88-92%. The technical advances for implantation include preformed guide sheaths to cannulate the CS, over the wire leads with passive fixation mechanism, and surgical placement methods. Device-specific CRT features include optimizing heart failure through insurance of a high percentage of pacing, heart failure monitoring, atrioventricular and interventricular timing, and avoiding double ventricular sensing. Furthermore, arrhythmic co-morbidities of heart failure such as atrial fibrillation and ventricular tachyarrhythmias can also be managed. Recent prospective trials suggest that there is a 30% reduction in heart failure hospitalization with CRT, and preliminary results suggest a survival benefit with CRT and implantable cardioverter defibrillator over optimal medical therapy.

A Fast and Simple Echocardiographic Method of Determination of the Optimal Atrioventricular Delay in Patients After Biventricular Stimulation

The optimization of atrioventricular (AV) delay is known to significantly contribute to maximum cardiac performance. The aim of this study was to validate a new, fast, and simple echocardiographic method of identifying the AV delay that provides the maximum cardiac output (CO). Right heart catheterization and Doppler echocardiography of transmitral filling were performed simultaneously in 18 patients with heart failure and at least minimum functional mitral regurgitation treated with atrial synchronized biventricular pacing. CO derived from catheterization and Doppler filling parameters were measured at the predicted optimal AV delay (oAVD), the short AV delay (oAVD - 50 ms), and the long AV delay (oAVD + 28 ms on average/range, +10 ms to +50 ms) during a constant heart rate. The AV delay was regarded as optimal if the end of atrial contraction (represented by the end of A wave of transmitral filling) coincided with the beginning of ventricular contraction (heralded by the onset of the systolic component of mitral regurgitation). Prediction of the optimal AV delay included the following steps: (1) The maximum AV delay at which full ventricular capture is still preserved was found under electrocardiographic control. (2) This value, decreased by 5 to 10 ms, was designated as "the testing long AV delay," and the time interval from the end of the A wave to the onset of the systolic component of mitral regurgitation (time t1) was measured at this setting. (3) oAVD was simply calculated as "the testing long AV delay"- time t1. The CO measured at the oAVD (4.5 +/- 0.7 1. min-1) significantly exceeded those at the short AV delay (4.3 +/- 0.7 1. min-1, P < 0.01) and the long AV delay (4.4 +/- 0.8 1. min-1, P < 0.01), respectively. The method correctly determined the maximum CO in 78% of the patients. In conclusion, Doppler echocardiography enables very rapid and accurate optimization of AV synchrony in patients after the implantation of a biventricular pacemaker.

A relative value method for measuring and evaluating cardiac reserve

BACKGROUND

Although a very close relationship between the amplitude of the first heart sound (S1) and the cardiac contractility have been proven by previous studies, the absolute value of S1 can not be applied for evaluating cardiac contractility. However, we were able to devise some indicators with relative values for evaluating cardiac function.

METHODS

Tests were carried out on a varied group of volunteers. Four indicators were devised: (1) the increase of the amplitude of the first heart sound after accomplishing different exercise workloads, with respect to the amplitude of the first heart sound (S1)recorded at rest was defined as cardiac contractility change trend (CCCT). When the subjects completed the entire designed exercise workload (7000 J), the resulting CCCT was defined as CCCT(1); when only 1/4 of the designed exercise workload was completed, the result was defined as CCCT(1/4). (2) The ratio of S1 amplitude to S2 amplitude (S1/S2). (3) The ratio of S1 amplitude at tricuspid valve auscultation area to that at mitral auscultation area T1/M1 (4) the ratio of diastolic to systolic duration (D/S). Data were expressed as mean +/- SD.

RESULTS

CCCT(1/4) was 6.36 +/- 3.01 (n = 67), CCCT(1) was 10.36 +/- 4.2 (n = 33), S1/S2 was 1.89 +/- 0.94 (n = 140), T1/M1 was 1.44 +/- 0.99 (n = 144), and D/S was 1.68 +/- 0.27 (n = 172).

CONCLUSIONS

Using indicators CCCT(1/4) and CCCT(1) may be beneficial for evaluating cardiac contractility and cardiac reserve mobilization level, S1/S2 for considering the factor for hypotension, T1/M1 for evaluating the right heart load, and D/S for evaluating diastolic cardiac blood perfusion time.