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

Impact of haemodynamic SonR sensor on monitoring of left ventricular function in patients undergoing cardiac resynchronization therapy

Aims

The haemodynamic SonR sensor is able to measure myocardial contractility. The isometric effort is useful in quantifying left ventricular (LV) performance. We investigated the amplitude changes in SonR signal over time and during static exercise according to the recovery of the left ventricle.

Methods and results

Twenty five patients [18 male, 70 ± 8 years, LV ejection fraction (LVEF) 29 ± 5%, in sinus rhythm] underwent biventricular SonR implantable cardioverter defibrillator implant. After procedure and at 6 months, each patient underwent detection of SonR signal and continuous measurement of blood pressure, at rest and during isometric effort. During evaluation at baseline device was programmed in VVI at 40 bpm while in DDD at 60 bpm at follow-up. At 6 months, LV reverse remodelling was investigated. Cardiac resynchronization therapy patients were considered responders when an absolute improvement in LV ejection fraction ≥ 5% occurred. At 6 months, 14 (56%) patients were responders and 11 (44%) non-responders (mean LVEF 40 ± 10% vs. 27 ± 6%, respectively). In responders, SonR value did not significantly change at follow-up compared to baseline (P = 0.894). At follow-up, SonR value was not significantly different between two groups (P = 0.651). SonR signal significantly increased during isometric effort in responders (P = 0.002) while it slightly decreased in non-responders at follow-up (P = 0.572). No differences were observed in response to isometric effort between two groups at baseline (P = 0.182, P = 0.069, respectively).

Conclusions

The absolute SonR amplitude provides limited information on the status of LV performance. The variation in SonR signal during static exercise is more likely to identify responders at follow-up.