Lung Impedance Monitoring In Treatment of Chronic Heart Failure

Lung Impedance Monitoring In Treatment of Chronic Heart Failure

Heart failure is a major clinical problem that is increasing in magnitude and the cost of management of heart failure is escalating. A significant part of this cost is related to unplanned acute presentation to emergency departments and hospitalisation with worsening shortness of breath due to increased fluid content in the lungs.

Many heart failure patients are already fitted with defibrillators to protect them from the risk of fast heart rhythms and sudden death and are followed up in both the heart failure clinics and defibrillator clinics. Recently some of the defibrillators fitted have been equipped with an extra function that can detect and warn of changes in the fluid content of the lungs very early even before the patient starts to complain of any shortness of breath and before any signs of fluid overload are seen clinically. However, it is not known how to deal with these warnings if they occur very early and it is not known whether a medical intervention at his stage is beneficial to prevent progression and eventual hospital admission. In the majority of cases, early warnings of this kind are ignored or this function is disabled at implantation of the device.

The current study will involve patients who have already been fitted with a device with the above capability. The investigators will use the new function to guide management of these patients and compare their outcome with similar patients who are fitted with devices without it. The investigators will attempt to manage early warnings by a predetermined increase in medications in a group of patients and compare their clinical course to a similar group in whom no action is taken.

Inclusion Criteria:

• Previously fitted with an ICD or a CRT-D device for primary or secondary prevention (for at least 34 days) with a Medtronic Optivol capable Device
• Previous hospital admission for decompensated heart failure
• Left ventricular systolic dysfunction (EF <50%)
• Currently compensated heart failure with a functional class of III or better
• All patients will be on optimal medical treatment including a beta blocker, an ACEI (or ARB) and spironolactone unless contraindicated or not tolerated

Exclusion Criteria:

• Decompensated patients who have NYHA class IV or clinical signs of lung congestion at time of evaluation (these patients may be included later if/when their NYHA class improves)
• Patients with a high Optivol fluid index at time of evaluation (these patients may be included later when the Optivol fluid index comes down)
• Patients with advanced renal failure ± dialysis (Chronic Kidney Disease class 4 or 5 with an estimated GFR of <30 ml/min)