Following heart transplant allocation system changes, there have been an increasing number of implantations of continuous flow left ventricular assist devices (CF-LVADs) as destination therapy.1 These patients typically are older with increased comorbidities; thus, are more likely to suffer from malignancies following CF-LVAD implantation. Cancer treatment for these patients are also increasingly individualized but special consideration is required to determine the direct and indirect effects on the CF-LVAD device itself as well as device–patient interactions. We present a case report of a CF-LVAD patient diagnosed with non–small-cell lung cancer who underwent treatment with proton beam therapy and chemotherapy.
A 77 year old man with a history of nonischemic cardiomyopathy, recurrent ventricular tachycardia status post ablation, and second degree atrioventricular block status postimplantation of a dual-chamber pacemaker with upgrade to a dual-chamber implantable cardioverter defibrillator (ICD) in 2014 was implanted with a HeartMate II LVAD (Abbott Laboratories, Abbott Park, IL) as destination therapy. Postimplantation course was complicated by an intraventricular hemorrhage requiring ventriculoperitoneal shunt placement, respiratory failure requiring tracheostomy placement, and device exchange for acute pump thrombosis two months after implant. After a period of acute rehabilitation, he eventually was able to discharge home where he reported a good quality of life.
Approximately 2 years following LVAD implant, a new mass was discovered in the left lung on chest x-ray during routine cardiac evaluation. Work-up revealed a T3N1M0 (stage IIIA) squamous cell carcinoma of the left upper lobe with possible invasion into the paravertebral fat and aorta as well as a satellite lesion in the superior segment of the left lower lobe (Figure 1). After discussion with a multidisciplinary thoracic tumor board, he was not felt to be a surgical candidate due to comorbidities and extensive disease. The patient was successfully computed tomograpy simulated, and the decision was made to proceed with concurrent proton beam radiation and chemotherapy.
Treatment with external proton beam radiation therapy was administered as 60 Gy over 30 fractions and dose-reduced (75%) carboplatin and paclitaxel combined chemotherapy. An anesthesiologist or nurse anesthetist and VAD technician were present for each session for monitoring and in case of device malfunction. He did well throughout treatment with minor side effects including mild esophagitis, fatigue, cough, and radiation dermatitis. There were no immediate respiratory adverse events during treatment and no malfunction of either ICD or CF-VAD. No unexpected alarms occurred during or after treatments. The log files were interrogated before and at the end of treatment. Pretreatment power elevations occasionally reached 11–12 W in the context of an lactate dehydrogenase of 392 U/L, and end of treatment power elevations occasionally reached 10 W with an improved lactate dehydrogenase of 325 U/L. Unfortunately, he was admitted shortly after completing treatment for a streptococcal pneumonia with bacteremia in the setting of neutropenia. After nearly 1 month in the hospital, with evidence of new VAD thrombosis, the decision was made to pursue comfort care and the patient passed away.
Previously, LVAD patients requiring radiation treatment for malignancy have received photon radiation, which has been demonstrated to be safe and effective.2,3 To our knowledge, this is the first report of a patient with a HeartMate II and ICD who was treated with proton beam therapy.
Radiation therapy can be offered in two forms: either photo or proton beam therapy. Currently, photon beam radiotherapy is the standard of care for external beam radiation in patients with early stage non–small-cell lung cancer and is delivered to a target through multiple x-ray beams. While proton beam therapy has been used since the 1950s, this technology has been slow to adoption clinically due to high costs of equipment as well as a steep learning curve to implementation. Proton therapy directs protons through sophisticated modeling to a target with minimal radiation outside of the tumor.4 Proton beam therapy may offer a survival advantage with less risk to surrounding tissue particularly for larger or central tumors with a different toxicity profile, although there is currently a lack of definitive evidence to support these conclusions.5 However, proton radiation has neutron scatter whereas photon radiation does not. Previous study has demonstrated malfunction of implantable cardiac devices in patients who received proton beam therapy.6,7 We felt that despite the potential effects of neutron scatter, the potential advantages of improved survival with minimal radiation effect to surrounding lung tissue would make proton beam therapy a better choice for treatment.
Multiple discussions were undertaken between the device manufacturer, the multidisciplinary LVAD team, and the radiation oncology team to ensure safety and functionality of the patient’s CF-LVAD. The main concern for radiation treatment was the possible effect on electronic components. The HeartMate II does not contain electronics within the pump; thus, neutron scatter was only of minor concern for this device. However, the HeartMate III (Abbott Laboratories) device contains electronics within the pump itself, so this could pose potential concerns with this newer generation device. Discussion between the multidisciplinary team and device manufacturer would need to be undertaken if a patient presents with a chest malignancy requiring radiation and a HeartMate III. Our radiation oncologists felt that because the HeartMate II LVAD was so inferior to the tumor, the risk of neutron damage was minimal. Additionally, in vitro testing of the HeartWare HVAD (HeartWare Inc., Miami Lakes, FL), which also does not contain electronic features within the pump, demonstrated safety of proton beam therapy with respect to changes to device function or signs of external damage.8 Other device components, specifically the controller and driveline, were also taken into consideration. The controller can be shielded outside of the room during proton therapy and exchanged quickly should scatter effect compromise functionality; however, it was not possible to shield the drive line and controller during treatments inside the therapy room because the shield would need to be two feet thick. After discussion among team members, it was felt that the risk of shielding requiring extension to bring the batteries outside of the treatment room outweighed the benefit. Finally, the manufacturer felt that based on in vitro testing of the HeartMate II with photon therapy demonstrating no changes to the driveline itself,9 it would be reasonable to consider proceeding with proton therapy.
In conclusion, proton beam therapy was safe and well-tolerated in a HeartMate II LVAD patient with a combined pacemaker-automatic implantable cardioverter defibrillator. This case scenario will be encountered more frequently in the future with increases in destination therapy LVAD patients requiring treatment for malignancy. Oncologic interventions and therapeutic strategies are frequently individualized for each patient, and thorough discussions to develop a multidisciplinary treatment plan should include collaboration with the LVAD team when these interventions involve radiation of an LVAD patient.
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