‘Bailout’ Ablation for Cardiogenic Shock and Refractory VT for Patients on Mechanical Support

Of 21 consecutive patients with refractory ventricular tachycardia (VT) in cardiogenic shock, most (81%) could be successfully weaned off mechanical support following radiofrequency ablation. So reports a group of Cleveland Clinic clinicians in an analysis published in Circulation: Arrhythmia and Electrophysiology. All of the patients had previously been unable to be removed from mechanical support despite antiarrhythmic drug therapy.

“Managing this critically ill group of patients is extremely challenging,” says Cleveland Clinic cardiologist Ayman Hussein, MD, senior author of the paper. “Ablation as a last resort proved to be a viable option, allowing liberation from mechanical hemodynamic support shortly afterward. At Cleveland Clinic, we are fortunate to have an excellent infrastructure that allows us to take care of these critically ill patients. Such results could only be achieved with the support and expertise of our colleagues in cardiac intensive care, cardiac surgery and heart failure medicine.”

A setting with little choice

Patients on mechanical support with cardiogenic shock and ventricular arrhythmias that cannot be controlled with antiarrhythmic drugs have few options: either heart transplantation or bailout ablation of ventricular arrhythmia. VT ablation is especially difficult in this setting of hemodynamic compromise, which hampers the ability to maintain the arrhythmia long enough to allow for adequate mapping and ablation without further deterioration. Little evidence is available on outcomes of bailout ablation under these circumstances.

Patient population

Consecutive patients with cardiogenic shock and concomitant refractory ventricular arrhythmia who underwent bailout ablation due to inability to wean off mechanical support were identified from a prospectively maintained Cleveland Clinic registry from 2010 to 2017.

Among the 21 patients identified, median age was 61 years, and 86% were male. Median left ventricular ejection fraction was 20%, and 81% had ischemic cardiomyopathy. Median PAINESD score, which predicts periprocedural acute hemodynamic decompensation in patients undergoing VT ablation, was 18 ± 5 (out of 35 maximum).

Mechanical support devices in place prior to the procedure were as follows:

• Intra-aortic balloon pump (IABP), 14 patients (67%)
• Impella CP, 2 patients
• Extracorporeal membrane oxygenation, 2 patients
• ECMO and IABP, 2 patients
• ECMO and Impella CP, 1 patient

Patients were maintained on a median of two antiarrhythmic drugs, with most (n = 14; 67%) on a combination of amiodarone and lidocaine. Others were on either amiodarone alone (n = 2), lidocaine alone (n =3), procainamide alone (n = 1) or amiodarone alone (n =1).

Procedural details

Clinical VTs were inducible and activation mapping was possible in 13 patients (62%). Six patients (29%) had premature ventricular contraction (PVC)-induced ventricular fibrillation/VT, and in two patients (9%), VT could not be induced.

The ablation procedures targeted the clinical VTs and PVCs in addition to empiric scar modification. At the end of the procedure, 91% of patients had no inducible VTs.

Outcomes

Overall, the following outcomes were found after VT ablation:

• 17 patients (81%) were successfully weaned off mechanical support, which occurred an average of 2 ± 1.4 days after ablation.
• 15 patients (71%) were discharged from the hospital, which occurred a median of 20 days (interquartile range [IQR], 10.5-26) after ablation.
• Six patients (29%) died during the index admission; four of these patients died while still on mechanical support.

Outcomes among the 15 survivors included the following:

• Median duration in cardiogenic shock was 5 days (IQR, 2-9 days) before ablation and 1 day (IQR, 1-1 day) after ablation.
• Median length of intensive care unit stay was 8 days (IQR, 5-12.5 days) after ablation.
• One patient received a heart transplant during the index admission.
• Five patients received a left-ventricular assist device within 3 months of discharge.
• One patient had recurrent VT requiring defibrillator shocks 96 days after discharge; all others had no recurrent VT during one-year follow-up.
• Two patients died within the first year after ablation (one from sudden cardiac death after 362 days, one from an unknown cause more than 6 months after ablation).

First known study of its kind

Dr. Hussein notes that mortality was related mostly to worsening cardiogenic shock. Comparing the 15 patients who survived to discharge with the other six patients revealed that survivors were more likely to be male (93% vs. 67%) and to have the following:

• Higher left ventricular ejection fraction (30% vs. 19%)
• Lower PAINESD score (17 [IQR, 14-20] vs. 20.5 (IQR, 15-23])
• Shorter duration of cardiogenic shock pre-ablation (3 days vs. 9 days)
• Shorter overall duration in cardiogenic shock (8 days vs. 13 days)

Patients presenting with VT before shock onset fared better than patients who subsequently developed VT after presenting in shock requiring hemodynamic support. Survivors and nonsurvivors did not differ in terms of likelihood of having ischemic versus nonischemic cardiomyopathy.

While the analysis is limited by its small size and retrospective design, the authors note that it is the only study they’re aware of that investigated VT bailout ablation in this high-risk setting.

“Our findings confirm that ablation bailout for ventricular arrhythmia can save lives in this situation,” observes co-author Oussama Wazni, MD, Section Head of Cardiac Electrophysiology at Cleveland Clinic. He adds, however, that because the study reflects practice in a tertiary care center with staff highly experienced in intensive care, VT ablation and cardiac surgery, the results may not be applicable to smaller or nontertiary care institutions.