Cardiac contractility modulation (CCM) is a non-pharmacological treatment option for patients diagnosed with chronic, moderate-to-severe heart failure. This therapy is specifically designed to treat heart failure with reduced ejection fraction (HFrEF), a condition where the heart’s main pumping chamber cannot effectively push blood out. CCM involves implanting a small device that delivers precisely timed electrical signals to the heart muscle. The goal of this device-based therapy is to enhance the heart’s ability to contract and improve its overall pumping capacity.
How Cardiac Contractility Modulation Works
The mechanism of CCM is distinct from other cardiac devices because it focuses on improving the strength of the heart’s natural beat rather than regulating its rhythm. The device delivers non-excitatory electrical pulses to the heart muscle cells, or myocytes, during the absolute refractory period. This period is the brief time immediately following a heartbeat when the muscle is completely unable to be excited again to start a new contraction.
The signals are specifically synchronized to this non-responsive phase of the cardiac cycle, which is why they do not trigger an extra, premature beat. Instead of initiating a new contraction, the high-voltage, biphasic electrical pulses modify the cellular environment within the heart muscle. This modification primarily affects the handling of calcium ions inside the cells, which are the fundamental trigger for muscle contraction.
Heart failure often involves abnormal calcium cycling, leading to weaker and less efficient contractions. CCM signals improve this process by increasing the amount of calcium available within the cytosol during the systolic phase, which enhances the force of the subsequent natural contraction. Over time, the therapy also appears to reverse abnormal gene expression patterns that develop in a failing heart. These changes facilitate reverse remodeling, helping the heart muscle return toward a more normal, efficient state without increasing oxygen consumption.
CCM is not a pacemaker, which regulates slow or irregular heart rhythms, nor is it an implantable cardioverter-defibrillator (ICD), which treats rapid arrhythmias. CCM is a therapy that acts at the cellular level to improve the mechanical pumping function of the heart. The therapy is delivered for several hours a day, often in one-hour sessions, to maximize its beneficial effects on the myocardial cells.
Components and Implantation of the CCM Device
The Cardiac Contractility Modulation system consists of two main hardware components: a pulse generator and the leads. The pulse generator is a small, pacemaker-like device that houses the battery and the electronic circuitry responsible for generating and timing the electrical signals. This generator is implanted under the skin in the upper chest, often near the collarbone, similar to a standard pacemaker implant.
The system uses two or three leads, which are thin, insulated wires threaded through veins to the heart. These leads are positioned on the right ventricular septum, the wall separating the two lower chambers. The electrodes on the leads deliver the specific CCM electrical signals directly to the heart muscle tissue.
The implantation procedure is minimally invasive and is performed using local anesthesia and light sedation. The process takes between one to two hours, and many patients return home the same day or after an overnight stay for observation. After implantation, the device is activated and programmed to ensure precise signal delivery. The pulse generator contains a rechargeable battery, which patients recharge weekly for about an hour using an external charger placed over the device.
Who is a Candidate for CCM Therapy?
CCM therapy is a specialized treatment option for heart failure patients who have not found adequate symptom relief with standard medical treatments. Candidates have symptomatic chronic heart failure classified as New York Heart Association (NYHA) functional class II or III. This means they experience symptoms like fatigue, shortness of breath, or palpitations with ordinary physical activity (Class II) or less than ordinary activity (Class III).
A defining criterion for eligibility is having heart failure with a reduced left ventricular ejection fraction (LVEF), ranging between 25% and 45%. This range indicates that the heart’s pumping function is significantly impaired but not in the most severe category. CCM is considered for patients who are not candidates for Cardiac Resynchronization Therapy (CRT), which is another common device treatment for heart failure.
Patients who benefit most from CCM have a narrow QRS complex on their electrocardiogram, less than 130 milliseconds, which disqualifies them from receiving CRT. CCM fills a treatment gap for symptomatic HFrEF patients who have failed to improve on optimal medical therapy and lack the specific electrical conduction delay required for CRT. The therapy is intended for use when guideline-directed medical therapy has been optimized for at least three months without sufficient improvement in symptoms or functional capacity.