Transcatheter aortic valve replacement effective for high-risk and inoperable patients with severe aortic stenosis [PARTNER 1 and PARTNER 2 trials]

1. [PARTNER 1 trial] Transcatheter aortic valve replacement (TAVR) in high-risk surgical patient was shown to have similar outcomes as surgical aortic valve replacement therapy (SAVR).

2. [PARTNER 2 trial] TAVR proved to be more effective than standard treatment for patients with inoperable aortic stenosis.

Evidence Rating Level: 1 (Excellent)

Study Rundown: Aortic stenosis is a common form of heart disease among the elderly. If left untreated the disease leads to hemodynamic instability and is often fatal. Treatment of the condition eventually requires making the decision whether or not to pursue surgical intervention. In many patients this decision is complex given that the elderly are most affected by the condition and are often times questionable surgical candidates. Transcatheter aortic valve replacement (TAVR) is a less invasive option for individuals requiring aortic valve replacement but not suited to traditional surgical aortic valve replacement (SAVR). Results of two related trials on the subject were published in Lancet. The authors of these studies sought to determine how TAVR compares with SAVR in high-risk surgical patients (PARTNER 1 trial) and those with inoperable aortic stenosis (PARTNER 2 trial) with regards to mortality at 5 years. TAVR appeared to be superior or comparable to SAVR in most metrics, although was associated with higher mortality in certain subgroups with moderate-to-severe post-procedural aortic regurgitation (see In-Depth). These studies benefit from drawing from a large and geographically diverse patient population, thus, allowing for high degree of generalizability. It is unfortunate that one limitation to these studies was that quality of life (QOL) data was not collected after 1 year. Knowing how TAVR affects the QOL of patients in the long term compared to surgical or standard non-surgical treatment would have provided additional insight into the potential benefits of TAVR.

Both studies were funded by Edwards Lifesciences. The funder designed and monitored the study and participated in the selection and management of the study sites and data collection.

Click to read the PARTNER-1 study in Lancet

Click to read the PARTNER-2 study in Lancet

Relevant Reading: On the natural history of severe aortic stenosis

In-Depth [randomized controlled trial]: The PARTNER-1 study included 699 high surgical risk patients with severe aortic stenosis (valve area ≤0.8 cm², and resting or inducible peak velocity ≥4 m/s or a mean valve gradient ≥ 40 mm Hg) from 25 centers from the United States, Canada, and Germany. The overall Society of Thoracic Surgeons Predicted Risk of Mortality score was 11.7% for the study population. The authors found that at 5 years post treatment all-cause mortality was 67.8% in patients receiving TAVR compared with 62.4% in patients receiving SAVR (hazard ratio 1.04, 95% CI 0.86-1.24; p=0.76). Additionally, there was no deterioration of implanted valves requiring surgical intervention in either group. Notably, at 30 days, 40 (14%) of the 280 patients in the TAVR group had moderate to severe aortic regurgitation, compared to 2 (1%) in the SAVR group (p<0.0001). Total aortic regurgitation was associated with increased 5-year mortality risk in the TAVR group (p=0.003).

The PARTNER-2 study enrolled 358 patients with inoperable aortic stenosis from the same 25 centers as with PARTNER-1. Patients were assigned to receive either TAVR treatment or standard non-surgical treatment for aortic stenosis. Risk of death was found to be 71.8% in patients receiving TAVR treatment and 93.6% in patients receiving standard treatment (HR 0.50, 95% CI 0.39-0.65; p < 0.0001). At 5 years, the risk of cardiovascular-related mortality was 57.5% in the TAVR group, compared to 85.9% in the standard treatment group (p<0.0001). The risk of stroke at 5 years was 16.0% in the TAVR group, compared to 18.2% in the standard group (HR 1.39; p=0.555). Notably, for patients with post-procedural moderate-to-severe paravalvular leak, the 5-year all-cause mortalities were not significantly different between the two groups (p=0.510).

Image: PD

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