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Having an implantable cardioverter-defibrillator (ICD) on top of a newer continuous-flow left ventricular assist device (LVAD) did not make death less likely for heart failure patients, according to an analysis of the INTERMACS Registry.

Over 5 years, patients with an ICD were (HR 1.20, 95% CI 1.04-1.39) and to pass away unexpectedly during LVAD support (HR 1.33, 95% CI 1.03-1.71), A. Reshad Garan, MD, of Columbia University Medical Center in New York, and colleagues reported in the December 1 issue of JACC: Heart Failure.

"Importantly, in no subgroup was the presence of an ICD associated with improved survival, including those with a prior ventricular arrhythmia," they said, adding that "we do believe these findings may put into question the need for primary prevention ICDs in patients with a continuous-flow LVAD."

However, the researchers also argued that "for patients who have received appropriate shocks whether before or after LVAD implantation ... maintenance of ICD therapy is important to prevent the morbidities associated with prolonged ventricular arrhythmia (most notably right ventricular failure)."

"As such, we advocate for generator changes in patients with prior ventricular arrhythmia if required after LVAD implantation," Garan's group said.

This combination of devices, compared with a newer continuous-flow LVAD alone, was associated with:

• Fewer LVADs explanted for recovery (HR 0.53, 95% CI 0.29-0.98)
• A trend for more transplantations (HR 1.16, 95% CI 0.99-1.35)
• More ventricular arrhythmias treated by defibrillation or cardioversion (0.12 events per year versus 0.10, RR 1.27, 95% CI 1.10-1.48)
• More rehospitalizations (1.92 events per year versus 1.79, RR 1.08, 95% CI 1.04-1.12)

"While the finding of a higher rate of ventricular arrhythmias in the ICD group might be puzzling to some, this finding was likely due to the fact that those patients had devices that detected and treated arrhythmias; patients with no ICDs might have experienced similar rates of arrhythmias that went undetected due to the absence of a device that provides continuous monitoring," according to an by Sean Pokorney, MD, MBA, and Sana Al-Khatib, MD, MHS, both of Duke University Medical Center in Durham, North Carolina.

The study's findings appear to run counter to what was previously reported to be a survival advantage for ICD recipients with pulsatile LVADs.

The bottom line: "Prospective randomized trials are needed in patients with continuous-flow LVADs to guide the use of ICDs in these patients," Pokorney and Al-Khatib wrote.

"An optimal approach to ICD programming in patients with continuous-flow LVADs needs to be established. Studies of hemodynamic and physiologic response to ventricular arrhythmias would be informative for understanding the tolerability of ventricular arrhythmias in patients with continuous-flow LVADs," Pokorney and Al-Khatib wrote. "An outcomes-based randomized trial is needed to definitively determine whether ICDs are beneficial in patients with continuous-flow LVADs, as well as to determine the quality of life and healthcare utilization impact of ICDs in this patient population."

From the large INTERMACS registry, the investigators matched continuous-flow LVAD recipients with ICDs to ICD-less controls according to propensity score (n=2,209 for each group). This matching attempted to neutralize the baseline differences that existed between groups.

Continuous-flow LVADs supported patients for a median of 12 months in both groups.

Rates of hemorrhagic stroke were the same whether patients had ICDs or not (RR 1.01, 95% CI 0.81-1.26), Garan and colleagues found.

Pokorney and Al-Khatib noted the study's lack of information on metrics such as right ventricular function or pulmonary vascular resistance, indications for ICD, and time elapsed between ICD implantation and LVAD placement.

There was potential for unmeasured confounding despite propensity score matching, the investigators also admitted.