Cardiac Resynchronization Therapy for the Complex Heart Failure Patient

There are currently over six million Americans living with heart failure; this number is expected to rise sharply in the coming years to an estimated eight million patients by 2030.¹ Heart failure patients often present with comorbid conditions that can complicate care. Moreover, heart failure patients form a heterogeneous population, such that therapeutic choices depend in great measure on individual patient characteristics. Cardiac resynchronization therapy (CRT) offers numerous benefits, including a reduction in left ventricular remodeling,² but not all heart failure patients are appropriate candidates for CRT systems.³ This report describes the selection of the appropriate CRT system for a particularly challenging case.

A 68-year-old male presented to the emergency department at NewYork-Presbyterian Hospital with nonischemic cardiomyopathy and advanced heart failure (NYHA Class 3b). He had a history of non-Hodgkin lymphoma, and had completed his last round of chemotherapy a few months earlier. The patient had a mechanical aortic valve implanted over 20 years ago; a few months prior, he had been admitted for emergency repair of a type A aortic dissection.

 

The patient was admitted to the hospital’s critical care unit (CCU) to begin diuresis for his heart failure. An electrocardiogram (ECG) revealed right bundle branch block and left anterior fascicular block. There was no history of ventricular tachycardia (VT) or cardiac arrest, but his resting sinus rate was sometimes erratic, normally around 80 or 90 bpm at rest and exceeding 140 bpm on exertion. He had no history of cardiac arrest or ventricular tachycardia. He had a thin frame with a body mass index (BMI) of approximately 20. He had been on medical therapy for heart failure for six months. While in the CCU, he had multiple episodes of symptomatic high-grade AV block. Given this, he was referred for possible CRT-D device implantation.  

 

The decision to implant a CRT device led to a series of concerns because of his comorbidities. As a cancer patient, it could not be ruled out that he would need magnetic resonance imaging (MRI) in the future, so his device ideally would need to be MRI conditional. Because of his thin build, it was desirable to minimize the bulk of the CRT-D as well as the number of leads used. 

 

The Intica^® CRT-DX device (BIOTRONIK, Inc.) was considered as a possible way to provide device-based therapy to this patient. Its ProMRI^® technology allows for full-body MRI scans, and MRI AutoDetect helps minimize the time spent in MRI mode if the patient needs such imaging. This device offers a right ventricular lead with floating atrial dipole, allowing the benefit of atrial diagnostics without the need for additional hardware (no atrial lead required). MultiPole Pacing (MPP) provides programming versatility in allowing for sequential or simultaneous pacing from various ventricular vectors, which can help fine-tune CRT pacing. Likewise, a quadripolar left ventricular pacing lead provides pacing versatility with several programmable pacing and sensing configurations (the LV Vector Opt allows for rapid perioperative testing of optimal left ventricular pacing parameters). This device also offers Closed Loop Stimulation (CLS), a physiologic rate adaptation that helps the device better respond to physical exertion and acute mental stress. Finally, the device works with BIOTRONIK Home Monitoring® technology to provide the clinic with alerts for certain conditions. Given the patient’s severe heart failure, BIOTRONIK Home Monitoring could offer a way to closely follow his status without the need for frequent office visits or phone calls.

 

Once the patient had stabilized, an Intica CRT-DX device with two leads was implanted. The implantation proceeded uneventfully. The patient remained in the hospital for a few days, and device diagnostics reported a “slow”  VT event that was below the programmed detection cutoff rate of the device (160 bpm) for ICD therapy. This particular slow VT was nonsustained, but the CRT-DX system was reprogrammed so that the device would detect and treat VT at those rate ranges. The patient was put on amiodarone therapy to reduce the incidence of ambient ventricular tachyarrhythmias.

 

A few days after implant, the patient was discharged with a BIOTRONIK Home Monitoring system. The patient set it up successfully and has been transmitting regularly.

This case highlights the importance of CRT as a therapeutic option for many heart failure patients. This patient’s previous cancer complicated his care — chemotherapy can have cardiotoxic effects,⁴ so he was particularly vulnerable to cardiovascular complications — and device implantation could not compromise his ability to get an MRI. For that reason, the Intica CRT-DX system was an ideal choice for his clinical situation. Furthermore, it reduced the need to implant leads in his body but still give him the therapy he needed. The versatility allowed by this device to adjust pacing parameters was also helpful in optimizing CRT, and BIOTRONIK Home Monitoring enhanced patient safety.