Significant improvement in the control of symptoms related to paroxysmal supraventricular tachycardia (PVST) is resurrecting etripamil as a self-administered nasal spray a year after it failed to meet the primary endpoint in a phase 3 trial, according to a new analysis from this same study presented at the annual scientific sessions of the American College of Cardiology.
In the phase 3 NODE-301 trial, presented at the 2020 Heart Rhythm Society annual meeting, etripamil did not show an advantage over placebo at 5 hours for achieving sinus rhythm. Nevertheless, a new presentation of the secondary outcomes suggests substantial clinical benefit.
These advantages include significant reductions in PVST symptoms, a trend for fewer emergency room visits, and a degree of patient satisfaction that appears meaningful, according to Bruce S. Stambler, MD, an electrophysiologist affiliated with Piedmont Heart Institute, Atlanta.
The data, despite the phase 3 trial results, “support continued development of etripamil nasal spray acute treatment of PVST,” Dr. Stambler said.
Etripamil is an L-type calcium channel blocker. When administered by nasal spray, it reaches peak effects within about 10 minutes. But the action is short, with a decline in antiarrhythmia effects beginning about 30 minutes after the peak effect.
In the NODE-301 trial, which employed a 2:1 randomization ratio, 138 patients self-administered 70 mg of etripamil or placebo immediately upon experiencing a suspected episode of PVST.
Up until 45 minutes, the proportion of episodes that converted to sinus rhythm was about 66% greater (hazard ratio, 1.66; P = .02) on etripamil than placebo, but the advantage was then lost. By predefined primary endpoint of 5 hours, when 100% of placebo patients but not all etripamil patients had converted, there was a slight but nonstatistical advantage for placebo (HR 1.08; P = .1212).
However, because of the rapid onset and then the rapid offset of this agent, the 5-hour time point for comparing effects might not have been the optimal duration to compare effects, according to Dr. Stambler.
On the basis of safety of etripamil, which was not associated with any significant adverse events in NODE-301, and the early clinical effect, the investigators have looked again at the data.
For relief of patient-reported symptoms and patient-reported satisfaction, which were secondary endpoints of the study, the data support a clinical role, according to this new analysis.
Specifically, there were large differences on a 7-point scale for all of the measured symptoms of PSVT in favor of etripamil, including rapid pulse (P = .002), palpitations (P = .0001), dizziness (P = 0.01), shortness of breath (P = 0.008), and anxiety (P = 0.006). A numerical advantage for chest pain did not reach significance.
“In general, patients reported scores of 4 to 5 on this scale, which corresponds to ‘not satisfied’ to ‘satisfied,’ while the placebo-treated patients reported scores of 2 to 3, which corresponds to ‘dissatisfied’ or ‘very dissatisfied,’ ” Dr. Stambler reported.
The favorable patient experience is also reflected in the Treatment Satisfaction with Questionnaire for Medication (TSQM-9), which was another NODE-301 endpoint. Evaluated when patients were still blinded to their assigned therapy, the advantage of etripamil over placebo for both global satisfaction (P = .007) and treatment effectiveness (P = .002) were also highly statistically significant.
The subjective experience of patients appeared to be reflected in objective measures. When the two groups were compared for interventions in an emergency room, the need was reduced by about half (12.1% vs. 24.5%; P = .051) among those treated with etripamil. Although this just missed the conventional measure of statistical significance, it was close. Similarly, patients randomized to etripamil required numerically fewer rescue medications (14.0% vs. 26.5%; P = .059).
Adenosine was the most common of the rescue medications, according to Dr. Stambler. He said there was no difference between the groups in use of rescue oral therapies.
When comparing etripamil and placebo in the subgroup that did visit an emergency room for PVST, there was a delay in ER visits among those randomized to etripamil (116 vs. 79 minutes; P < 0.05), suggesting that this agent reduced the sense of urgency when PSVT symptoms develop, according to Dr. Stambler.
On average, the patients who enrolled in this trial had a PSVT history of about 1.5 years. In the year prior to enrollment, the mean number of ER visits was about nine.
In the trial design, patients were required to take a test dose of etripamil under observation by a physician before being sent home with their assigned therapy, but Dr. Stambler does not believe that the requirement, if the drug is approved, will be in the label.
Unexpectedly, many patients had symptom relief even without converting to sinus rhythm, Dr. Stambler acknowledged. He speculated that the reduction in heart rate associated with etripamil might have provided a relief of symptoms sufficient to relieve anxiety, producing the relative advantage for patient satisfaction.
Jodie L. Hurwitz, MD, director of the electrophysiology lab at Medical City Hospital, Dallas, indicated that there is a need for new options for PVST. An expert panelist during the session where these data were presented, she was particularly interested in rapid symptom relief.
“It would be great to have a therapy that could be self-administered at home. Patients would like it, too,” she said.
Mary N. Walsh, MD, a heart failure specialist affiliated with Indiana University, Indianapolis, sees a potential role of a self-administered therapy like etripamil in conjunction with wearable devices. She noted that the proportion of patients using these devices to monitor arrhythmias is increasing, providing a role for an easily transportable therapy that could be used quickly when symptoms develop.
However, after the negative phase 3 trial, more data must now be collected to satisfy the regulatory authorities that this agent is safe and effective. Dr. Stambler said that the developer is now committed to pursue these studies.
Dr. Stambler has a financial relationship with Milestone Pharmaceuticals, which is developing etripamil nasal spray and was the sponsor of this trial. Dr. Walsh and Dr. Hurwitz have no potential relevant conflicts of interest.
This article originally appeared on MDedge.com, part of the Medscape Professional Network.