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Optimal Placement of Pacemaker Leads Using Speckle Tracking Echocardiography Improves Outcomes

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Optimal Placement of Pacemaker Leads Using Speckle Tracking Echocardiography Improves OutcomesPlacing pacemaker leads in the optimal area of the left ventricle using computer-enhanced echocardiography imaging produced a 50 percent lower combined rate of all-cause death and hospitalizations compared to patients with conventional lead placement, say researchers.

In the first randomized clinical trial to report on the use of echocardiography for placement of pacemaker leads, Dr. Fakhar Kahn, clinical research fellow at Cambridge University, UK, reported the better overall results for patients with heart failure at this week’s American College of Cardiology’s 60th Annual Scientific Session (ACC.11).

“Optimal placement of pacemaker leads is determined by the location of cardiac scar tissue and areas of delayed heart muscle contraction, which vary considerably among patients,” said Khan in a prepared statement. “Our improved results with an individualized approach should change the way pacemaker leads are implanted in this population of patients.”

In the study, researchers randomly assigned 220 patients with left bundle branch block who were scheduled for cardiac resynchronization therapy (CRT) to either standard pacemaker implantation or a new procedure called, speckle tracking echocardiography (STE). Patients averaged 71 years old and ranged from 63 to 78.

Speckle tracking echocardiography (STE) is a non-invasive method for evaluating left ventricular global and regional function. It is named for the speckles that appear in grey scale two-dimensional echographic images caused by the scattering, reflection and interference of the ultrasound beam in myocardial tissue.

The speckles form “fingerprints” randomly distributed throughout the myocardium that represent tissue markers that can be tracked from frame to frame throughout the cardiac cycle by computer. In this study, researchers use STE to identify the latest area of contraction in the heart cycle, which has been associated with better response to CRT.

In the STE group, physicians implanted the wire leads to cardiac resynchronization pacemakers guided by speckle tracking echocardiography information to position the left ventricular lead within the site of latest contraction. In the control group, physicians implanted the CRT device using standard procedures without reference to the STE data.

All patients had the lead positions defined by biplane fluoroscopy. Patients were then classified into three groups, those with the lead implanted within the site of latest contraction, next to the site of latest contraction, or remote, defined as more than two segments away from the latest site of contraction. This analysis showed that a 61 percent of patients in the STE group had lead placement at the optimal site compared to 47 percent of the control group.

The echocardiography group had better overall results than the control group on all clinical endpoints, including a 70 percent improvement in the rate of response by reverse remodeling of the left ventricle, compared to 55 percent for the control group. Rate of response by reverse remodeling is a measure of improvement in heart function. The echo group also showed an average improvement on a standard scale for heart failure of 83 percent vs. 65 percent.

While there were no differences in the baseline characteristics between the two groups in terms of cardiac output, with an average of 4.77 liters per minute in the echocardiography group compared to an average of 4.67 liters per minute in the control group. After implantation, however, the average cardiac output for the echo group was 6.06 liters per minute compared to an average of 5.57 liters per minute in the control group.

Significantly, the results also showed that the closer the lead was placed to the optimal site, regardless of group, correlated with better outcomes. Only 8 percent of patients in either group whose left ventricular leads were place exactly within the target site died from any cause or were hospitalized compared to a 16 percent combined rate of death from any cause or hospitalization due to heart failure in patients whose ventricular leads were placed adjacent to the optimal site.

Kahn noted that the software needed to convert standard echocardiography to speckles tracking echocardiography is easily installed by clinics using the conventional equipment.

STE software can be applied to any existing echocardiographic image at no additional risk to the patient,” Khan said. “It makes targeting of the lead feasible at any facility that’s already performing echocardiography and has the software in their system to analyze the images. That makes it widely accessible, even for small centers and non-university hospitals, where more and more pacemakers are being implanted.”

By Michael O’Leary, contributing writer, Health Imaging Hub

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