Interatrial Shunt Device to Reduce LA Pressure in Diastolic HF
What is the efficacy and safety of a transcatheter novel interatrial shunt device (IASD) in diastolic heart failure (HF)?
REDUCE LAP-HF (REDUCe Elevated Left Atrial Pressure in Patients with Heart Failure) is an open-label, multicenter, single-arm phase 2 study to determine the safety and efficacy of a novel transcatheter IASD. The study cohort was comprised of chronic diastolic HF patients, who were New York Heart Association (NYHA) functional class II-IV (left ventricular ejection fraction >40%), ages >40 years, with pulmonary capillary wedge pressure (PCWP) >15 mm Hg at rest or >25 mm Hg during exercise. They excluded patients with substantial right ventricular dysfunction (including a central venous pressure >14 mm Hg and tricuspid annular plane systolic excursion <14 mm). Other important exclusion criteria included recent (<3 months) myocardial infarction, coronary artery bypass grafting, or percutaneous coronary intervention; nonambulatory NYHA class IV HF; infiltrative or hypertrophic cardiomyopathy; and moderate or greater aortic stenosis or mitral regurgitation. The co-primary endpoints were the safety and performance of the IASD at 6 months, including measures of clinical efficacy (i.e., functional capacity and clinical status) analyzed per protocol. The investigators defined primary device performance endpoints as the proportion of patients with successful device implantation, the percentage of patients with a reduction in PCWP at 6 months either at rest or during exercise compared with baseline, and the presence of persistent left-to-right transdevice blood flow at 6 months. They defined the primary safety endpoints as periprocedural and 6-month major adverse cardiac and cerebrovascular events, defined as death, stroke, myocardial infarction, or a systemic embolic event (excluding pulmonary thromboembolism), or need for cardiac surgical device removal within 6 months.
IASD was successfully placed in 64 of the 68 eligible patients during the study period. The device was well tolerated; no patient had a periprocedural or major adverse cardiac or cerebrovascular event or need for cardiac surgical intervention for device-related complications during 6 months of follow-up. Approximately 52% (31 out of 60 patients) had a reduction in PCWP at rest, 58% (n = 34) had lower PCWP during exercise, and 39% (n = 23) had both of these criteria. The investigators found that mean exercise PCWP was lower at 6 months than at baseline, both at 20 watts workload (mean 32 mm Hg [SD 8] at baseline vs. 29 mm Hg  at 6 months, p = 0.0124) and at peak exercise (34 mm Hg  vs. 32 , p = 0.0255), despite increased mean exercise duration (baseline vs. 6 months: 7.3 min [SD 3.1] vs. 8.2 min [3.4], p = 0.03). The investigators reported that the device was patent at 6 months, as evidenced by left-to-right shunting (pulmonary/systemic flow ratio: 1.06 [SD 0.32] at baseline vs. 1.27 [0.20] at 6 months, p = 0.0004). At 6 months, median NYHA functional class had improved from III (interquartile range, II-III) to II (II-III; p < 0.0001), mean Minnesota Living with Heart Failure score from 49 (SD 20) to 36 (SD 23; p < 0.0001), mean 6-minute walk distance from 313 m (SD 105) to 345 m (SD 106; p = 0.0023) and supine exercise duration at the time of right heart catheterization from 7.3 min (SD 3.1) to 8.2 min (SD 3.4; p = 0.0275).
The study authors concluded that an IASD is feasible, safe, and reduces left atrial pressure during exercise, and could be a new strategy for management of diastolic HF patients.
Given that there is no definitive therapy for diastolic HF, the study findings are important. As the authors point out, the long-term sequelae of shunting on right hemodynamics are unclear. Validation of the study findings and more importantly long-term outcomes in a randomized double-blind trial is the next step.
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