NEW ORLEANS – Patients with chronic cardiomyopathy can be successfully weaned from ventricular assist devices, and certain parameters can predict long-term cardiac stability after explantation, according to German investigators.
"Unloading-promoted reversal of heart failure allows for long-term transplant-free outcomes after patients are removed from VADs. However, few patients with chronic cardiomyopathy have been weaned from VADs, and the majority only recently," said principal investigator Dr. Michael Dandel of the German Heart Institute Berlin. "The long-term outcomes of patients, therefore, and the reliability of criteria for making weaning decisions, are not well known."
At his clinic, 91 patients with chronic cardiomyopathy (CCM) as the underlying cause of heart failure were weaned from VADs between 1995 and 2010, including 75 weaned from left ventricular assist devices, 13 weaned from biventricular assist devices, and 3 weaned from right ventricular assist devices. Before VAD implantation, the patients had left ventricular ejection fraction (LVEF) values of 10%-20%.
These patients were evaluated as to the feasibility of weaning and to establish criteria that could predict long-term cardiac stability after VAD removal. "With this information, we can improve future weaning decisions and postweaning patient management," Dr. Dandel said at the annual meeting of the American College of Cardiology.
A total of 47 patients were evaluated. Of these 41 (87.2%) had idiopathic cardiomyopathy, 4 (8.5%) had histologic evidence of chronic myocarditis before VAD implantation, and 2 (4.3%) had chronic ischemic cardiomyopathy with severe left ventricular dilation.
Before VAD insertion, all patients had irreversible end-stage heart failure and required continuous positive inotropic support. No attempts were made to use VADs electively with the aim of myocardial recovery only, he said.
Postweaning results. Cardiac stability lasting at least 15 years was achieved by 2 patients, while 10 patients have been stable at least 10 years and 3 at least 5 years, he reported.
"At 5 years, only five patients, 10.6%, had died due to heart failure recurrence or weaning-related complications. Several patients died of other causes," he said.
Postweaning freedom from heart failure recurrence for all evaluated patients was 74% at 3 years and 66% at 5 years, but these results included nine patients at very high risk for poor outcomes. After 2002, when the investigators tightened their criteria for weaning, freedom from heart failure recurrence reached 100% at 3 years, he noted.
Pre-explantation variables predictive of outcomes. "Echo data obtained during ‘off pump’ trials proved to be reliable for detection of recovery during mechanical unloading," Dr. Dandel said. "In particular, off-pump [left ventricle] size, geometry, and ejection fraction were predictive of outcome after weaning, especially when history of heart failure was also considered."
For cardiac stability lasting at least 5 years, pre-explantation "off pump" LVEF of 50% or more was associated with a positive predictive value of 91.7%, while LVEF of 45% or more had a positive predictive value of 79.1%.
The positive predictive value of LVEF of 45% or more was approximately 90% if additional parameters were considered: pre-explantation left ventricle size and geometry, stability of unloading-induced cardiac improvement before VAD removal, and heart failure duration before VAD implantation.
Time to cardiac recovery seemed important, Dr. Dandel said. "Patients who had recurrences needed more time to show an improvement. They needed twice the duration of VAD support as patients who did not have a recurrence," he said.
"Definite cutoff values for certain parameters – including tissue Doppler-derived LV wall motion velocity – allowed us to formulate weaning criteria with high predictability for postweaning stability," he said.
Risk factors for heart failure recurrence. Dr. Dandel and his colleagues also identified several risk factors that predicted heart failure recurrence during the first 3 years after VAD removal. These factors, and their associated probability for recurrence, were:
• Preweaning off-pump LVEF less than 45% plus history of heart failure longer than 5 years (100%).
• Preweaning LVEF less than 45% (88.9%).
• Preweaning off-pump LVEF less than 50% plus left ventricular internal diastolic diameter greater than 55 mm (90%).
• Pre-explantation LVEF less than 50% and preexisting alteration of greater than 10% best value (87.5%).
• LVEF less than 50% plus relative wall thickness decrease of less than 10% during final off-pump trial (83.3%).
Of these, he emphasized the importance of the final off-pump trial values. "An off-pump ejection fraction less than 45% in patients with a history of heart failure for more than 5 years is an absolute contraindication for VAD removal," he noted. "All such patients in our study had a recurrence of heart failure."
Early instability of ejection fraction and unstable geometry also confer a high probability of recurrence. "A wall thickness increase by more than 10% means the reverse in modeling is not stable enough," he added.