SCar Location and Acute Haemodynamic Response to MultiPoint Pacing in Patients With Ischemic Cardiomyopathy (SCAR MPP Study)

Cardiac Resynchronization Therapy (CRT) is a proven treatment for heart failure.

CRT consists of a special pacemaker with two/three leads (insulated wires which take the electrical impulses from the device to the heart), one in the right ventricle, one in a vein on the outer surface of the left ventricle (in a vessel called coronary sinus or CS) and sometimes one in the right atrium (right top chamber of the heart). Tiny electrical impulses are simultaneously sent to the ventricles to make them beating together again in a more synchronised pattern. This leads to a coordinated, synchronous pumping action that, in most patients, translates into improved heart failure symptoms and improved quality and quantity of life, reducing the chance of being admitted to hospital with worsening heart failure. Unfortunately up to one third of the patients do not benefit from CRT therapy and to date there are no useful criteria to predict the response to CRT.

In an effort to improve the response rate to CRT, alternative methods have been developed. In particular, a new technology called MultiPoint Pacing (MPP) (St. Jude Medical, Sylmar, CA) has recently become available. It allows simultaneous stimulation of 2 different points in the left ventricle by using a single lead with four electrodes. This strategy should improve the pumping function of the heart by recruiting a larger mass of muscle. Although MPP is as safe and as effective as standard CRT pacing, the improvements to date in the heart pump function it gives over standard CRT pacing are variable and small.

Recent evidence suggests that MPP pacing could be particularly beneficial in some subgroups of patients, in particular patients with a previous history of heart attack resulting in scar formation in the left ventricle.

The investigators hypothesize that MPP works better when the lead is closer to the scar because this allows recruitment of areas with slow conduction, thus increasing synchronization further.

To this aim, they plan to compare, in each patient, the acute response produced by MPP on the cardiac function when the CS lead is placed close to myocardial scar and when it is placed far from scar respectively.