Patients with STEMI revascularized with PCI who had severely impaired left ventricular ejection fraction (LVEF) but no inducible ventricular tachycardia (VT) had good outcomes without the need for an implantable cardioverter-defibrillator (ICD), according to a study published Dec. 31 in Circulation.
Between 2004 and 2011, Australian researchers from Westmead Hospital at the University of Sydney enrolled consecutive STEMI patients who were treated with PCI. Patients with LVEF of 40 percent or less underwent an electrophysiology study (EPS) to identify patients at risk for sudden cardiac death. Patients with inducible VT received an ICD, but patients without inducible VT did not.
The researchers also included patients with LVEF of 30 percent or less or 35 percent or less with New York Heart Association class II/III heart failure who would be eligible for EPS. Patients with LVEF greater than 40 percent, not eligible for EPS, were the controls. After revascularization, patients with LV dysfunction started medical therapy, including beta-blockers, ACE inhibitors, statins and antiplatelet medications.
As the primary outcome, they assessed the combination of all-cause mortality and arrhythmia. The secondary outcome was the first arrhythmic event. Arrhythmia was defined as sudden cardiac death, resuscitated cardiac arrest and sustained VT or ventricular fibrillation documented by electrocardiogram.
EPS was performed in 128 patients with LVEF less than or equal to 30 percent/35 percent. Sixty-three percent of patients had heart failure. Less than 0.1 percent of control patients, 4 percent of EPS-negative and 90 percent of EPS-positive patients received ICDs.
There was no significant difference in the distribution of time to death or arrhythmia between controls and patients with LVEF less than or equal to 30 percent/35 percent and heart failure who were EPS-negative. Three years later, 91.8 percent of controls, 93.4 percent of EPS-negative and 62.7 percent of EPS-positive patients had no arrhythmia and were still alive.
“Re-vascularized STEMI patients with severely impaired LV function but no inducible VT have favorable long term prognosis without the protection of an ICD,” wrote Sarah Zaman, MBBS, and colleagues.
Mortality among these patients was low at three years, which the researchers attributed to “the improved mortality in the era of early revascularization for STEMI, optimal medical management and targeted ICD implantation.”
In an accompanying editorial, Alfred E. Buxton, MD, of Beth Israel Deaconess Medical Center in Boston, wrote that the findings should be interpreted carefully, considering that the study population was small and the follow-up time was short. He also argued that the low mortality could have been due a number of factors, including the pharmacologic management of the patients and their relatively young age.
Despite the limitations, Buxton noted that the findings suggest that it’s time to move way from ICD guidelines based on EF.
“Until we find ways to move past the current fad of EF-based guidelines, we will continue to waste money and harm patients, implanting ICDs in many that will not benefit, and withholding them from patients whose survival could be improved with ICD treatment.”