Preventing Sudden Cardiac Death Following Coronary Artery Bypass Graft

Case Description

A 69-year-old male experienced syncope while driving his car and subsequently was involved in an automobile accident. After being extracted from his vehicle by emergency response services (EMS), he was transported to the hospital. En route to the hospital he experienced sudden cardiac arrest (SCA), was defibrillated by EMS, started on an amiodarone drip and brought to the emergency room.

The patient was experiencing traumatic chest pain on his right side. He denied any other symptoms. The patient was alert and oriented in no acute distress. Cardiovascular exam revealed +S1, S2, and an S4 with a displaced point of maximal impact (PMI). A systolic murmur was auscultated 2/6. Lungs were clear bilaterally. Abdomen was soft with normal bowel sounds and no tenderness. Extremities revealed 2+ pulses femorally and radially with no evidence of clubbing or edema.

X-rays revealed fracture of his 6th and 7th right side ribs. An echocardiogram revealed moderate aortic stenosis and severe LV dysfunction with an ejection fraction (EF) of 25%. Initial lab test results showed normal cardiac enzymes, but subsequent testing revealed elevated levels. He was admitted to the intensive care unit (ICU) for further workup and management.  

The next morning, the patient underwent cardiac catheterization, which revealed triple vessel disease (Figure 1). His left anterior descending artery was chronically occluded with hetero-collateral filling from both the left and right, his right coronary artery was occluded, and a moderate lesion in his proximal circumflex was noted. A decision was made to transfer the patient to a nearby hospital to evaluate for coronary artery bypass surgery (CABG).

After consultation, the decision was made to proceed with CABG. An endoscopic harvest of the greater saphenous vein (SVG) was performed, with simultaneous sternotomy and harvest of the left internal mammary artery (LIMA). Coronary bypass was performed X 4 (LIMA to LAD, SVG to RCA, SVG to OM, and SVG to D2). Doppler interrogation revealed excellent flow through all grafts with increased movement of his anterior wall. Immediate post-CABG echocardiogram showed minimal improvement in EF to 25-30%. The patient tolerated the procedure well and was transferred to the ICU in stable but critical condition. 

Electrophysiology was consulted due to the patient’s past ventricular fibrillation (VF) arrest and underlying ischemic cardiomyopathy with EF of 25%. Given his recent revascularization and hopes of improvement in LV function, the patient was prescribed a wearable cardioverter defibrillator (WCD) (ZOLL LifeVest^®) with plans to reevaluate his EF in three months. The remainder of his hospital stay was unremarkable and he was discharged on the eighth day of his hospitalization. 

Eleven days after being discharged, the patient experienced SCA (Figure 2); the WCD appropriately detected ventricular tachycardia at a rate of 240 beats per minute and delivered a 150J biphasic treatment shock 48 seconds later (Figure 2). The treatment converted the arrhythmia to sinus bradycardia, which quickly transitioned into normal sinus rhythm. 

The patient was taken to the emergency room by EMS, admitted to the hospital, and implanted with a dual chamber ICD the following day.

Discussion

This patient suffered syncope while driving his vehicle, which resulted in an automobile accident. He regained consciousness while being extracted from the vehicle by EMS. During transport to the hospital, the patient experienced sudden cardiac arrest and was resuscitated by EMS. He was treated for the injuries from his accident and started on antiarrhythmic medications while tests were performed to determine the cause of the SCA. The diagnosis of severe triple-vessel disease resulted in a predictable treatment course of revascularization by CABG surgery. 

Electrophysiology was consulted pre-discharge. Despite the previous episode of SCA, it was hoped that the patient’s elevated SCA risk was transient and would be reversed by treating the ischemic cause, tissue recovery, and medical optimization. This patient’s EF was showing some improvement immediately after revascularization. It was hoped that his condition would continue to improve and that he might avoid the need for permanent SCA protection. However, all patients with a low EF post revascularization are considered at high risk of SCA. Utilizing a WCD provided the patient with protection from SCA, afforded the physician time to evaluate the extent of the patient’s recovery and subsequent long-term arrhythmic risk, and in this case, administered life-saving therapy. This case is an excellent example of balancing early risks post-CABG while the patient’s condition is stabilized in order to make appropriate long-term decisions on implantable cardiac defibrillator therapy.

Disclosure: Dr. Styperek reports no conflicts of interest regarding the content herein.