|HeartWare's Ventricular Assist System--Courtesy of HeartWare|
Citing a just-released survey of cardiologists and thoracic surgeons, Leerink equity analysts said that a clinical trial finding a stroke rate of 31% among heart failure patients on the HeartWare Ventricular Assist Device will not affect clinical decision-making.
In addition, 26 of 28 U.S. physicians surveyed expect the HVAD to secure FDA approval as a long-term destination therapy for heart failure patients; it's currently only approved as a bridge to transplantation for those awaiting a donated heart. The expanded indication would match that of rival left ventricular assist device, Thoratec's HeartMate II.
At first glance, the 31.1% stroke rate is damning, especially compared to the 12.7% rates among HeartMate II patients in the head-to-head trial. In April, HeartWare's ($HTWR) stock fell 6% on the data.
But the survey data seems to affirm Leerink's previously held view that FDA approval is likely. After all, the HVAD met its clinical endpoint of noninferiority to Thoratec's HeartMate II as a long-term solution as measured by stroke-free survival at two years after implantation. This apparent inconsistency with the negative stroke rate data occurred because the strokes suffered by patients on Thoratec's device were more likely to be fatal than those among HVAD patients, Leerink said in April.
In addition, the 20 European physicians surveyed said the 31% stroke rate is "not representative of current clinical practice," Leerink said. The physicians in Europe (where both devices are already approved for long-term use) said the stroke rate they've experienced is about 10% on the HVAD and 7% on the HeartMate II, which is broadly consistent with European registry data cited by Leerink in April.
Still, the FDA's decision will likely hinge on results of the HVAD's follow-up clinical trial, which is currently recruiting participants, according to ClinicalTrials.Gov. Crucially, the trial will only include patients who receive optimal blood pressure management. In April, HeartWare officials said the original trial's lack of emphasis on blood pressure management contributed to the high stroke rate.
If the expanded indication is approved, U.S. physicians expect HeartWare to grab one-third of the long-term destination therapy segment of the LVAD market by 2017. Based on clinical trial implants only, the HVAD currently has 16% market share of the destination therapy market. The device has a one-third share in the bridge to transplantation market in the U.S., projected by the physicians to increase to 45% by 2017.
In Europe, HeartWare has market share slightly above 50%, and Leerink expects rival Thoratec to gain some ground following the likely CE-mark approval of HeartMate III later this year.
The U.S. physicians interviewed implanted about 963 LVADs, or about a quarter of the domestic market, Leerink says. The European physicians interviewed implanted 315 LVADs in 2014, or 13% of the volume in that market, Leerink estimates.
In addition to the high stroke rates, the HVAD's string of safety and usability issues could be a concern for the FDA as it considers the expanded indication. The device has been hit with five Class 1 recalls in the past year for issues like defective blood pump controllers and accidental snagging or pulling of the driveline, which passes through the skin to connect the implanted pump to the controller.
Editor's Note: This article was corrected because a previous version misstated the overall size of the LVAD market. The correction specifies that the participants in the survey were responsible for only a subset of all the LVADs implanted.