Cardiac electrophysiological alterations and clinical response in cardiac resynchronization therapy with a defibrillator treated patients affected by metabolic syndrome

Abstract

Metabolic syndrome (MS) is a multifactorial disease that can affect clinical outcomes in patients treated by Cardiac Resynchronization Therapy with a defibrillator (CRT-d).Ninety-one patients received a CRT-d. According to clinical diagnosis, the study population was divided into 46 MS (cases) versus 45 no MS (controls) patients. These patients were followed by clinical, instrumental assessment, and device telemetric interrogations at follow-up. The design of the study was to evaluate the functionality of the CRT-d leads, the arrhythmic events, the CRT-d response, and the clinical outcomes at follow-up.At follow-up, there was a statistical significant difference, comparing MS versus no MS patients regarding the sensing, pacing, and impedance thresholds of the right atrium, right ventricle, and left ventricle leads. There was a statistically significant difference in the percentage of CRT-d responders comparing MS (n = 16, 51%) versus no MS (n = 40, 77%) patients (P = 0.017). MS may be predictive for hospitalization for heart failure worsening (hazard ratio 0.327, 95% confidence interval 0.096-0.943, P = 0.044) in CRT-d patients.MS is a complex multifactorial disease that may affect the functionality of CRT-d leads, the CRT-d response, and clinical outcomes in failing heart patients. These parameters may be detectable by follow-up monitoring.

Figure 1

Study flow chart representations. One hundred sixty patients [with chronic heart failure lasting for at least 3 months, New York Heart Association (NYHA) functional class II or III, left bundle brunch block, severe LVEF reduction (LVEF <35%)] and an indication for CRT-d treatment have been identified and screened for participation in this study. Ninety-six eligible patients were included in the study. Ninety-one patients received a CRT-d treatment. These patients were divided into metabolic syndrome (MS) patients, versus no MS patients (46 vs 45 pt). After the CRT-d treatment, these patients were ambulatory monitored.

Figure 2

Representation of biventricular cardiac resynchronization therapy with defibrillator (CRT-d), lead structure, components and section (left upper part), and electrical impedance, pacing and sensing CRT-d field (right part). In left upper part, in a left anterior oblique radiographic view, image shows that the red arrow is indicating the left ventricular lead, the black arrow is indicating right atrial lead, while black not continuous arrow is indicating the right pacing and defibrillator lead. In left inferior image part, representation of lead structure and its components. The electrode is implanted in myocardial wall. From device interrogation, we could have information about lead sensing, impedance, and pacing thresholds. Sensing is the P and/or R wave amplitude measurement expressed in milli Volt (mV). The impedance is the measurement of a constant current sent through the tissue between the “stimulation” electrode pair (with a measurement frequency of 16 Hz, asynchronous with the cardiac cycle, therefore calculated intrathoracic impedance, expressed in Ohm). Pacing threshold in mV for milliseconds (msec) is the output lower energy to have a myocardial wall capture. These functionality parameters are related to lead position, and contact in myocardial wall, and to the lead structure integrity. In the right part of figure, representation of electrical device action field.