Higher AMR Index Tied to Increased Mortality and Cardiovascular Events Post-TAVR: Study Finds

"Over 40 months, patients with AMR >250 experienced a 1.94-fold higher risk of major adverse cardiovascular events (HR: 1.94), reduced event-free survival, increased all-cause mortality, and a greater incidence of new-onset atrial fibrillation. These findings establish AMR as a significant marker for assessing long-term risks in TAVR patients," the researchers reported in the Journal of the American Heart Association.

The coronary microcirculatory resistance index is essential for predicting patient outcomes. Coronary angiography-based methods provide a simple and cost-effective way to assess microcirculatory function. Considering this, Hongliang Zhang, National Center for Cardiovascular Disease Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China, and colleagues explored the prognostic significance of a novel angiographic microvascular resistance (AMR) index in patients undergoing transcatheter aortic valve replacement.

For this purpose, the researchers prospectively included 335 patients with severe aortic stenosis who underwent transcatheter aortic valve replacement at Fuwai Hospital. AMR was calculated using coronary angiography before valve implantation. Patients were categorized into two groups based on an AMR cutoff of 250 (AMR ≤250 and AMR >250). The primary outcome was major adverse cardiovascular events, including all-cause mortality, heart failure-related readmission, and myocardial infarction.

Key Findings:

• During a median follow-up of 40 months, AMR was significantly higher in patients who experienced major adverse cardiovascular events.
• Patients with major adverse cardiovascular events had an AMR of 257 compared to 226 in those without such events.
• AMR was identified as an independent risk factor for major adverse cardiovascular events, all-cause mortality, and new-onset atrial fibrillation.
• Kaplan-Meier analysis showed that patients with AMR >250 had lower event-free survival rates for major adverse cardiovascular events (62.9% versus 75.1%; HR: 1.94).
• The increased risk was primarily due to higher all-cause mortality in patients with AMR >250 (75.7% versus 83.4%).
• Subgroup analyses confirmed these findings for major adverse cardiovascular events.

The researchers identified AMR as a reliable predictor of long-term adverse outcomes following transcatheter aortic valve replacement. While elevated AMR was not linked to increased short-term hospitalization or in-hospital complications, an AMR >250 was significantly associated with major adverse cardiovascular events, all-cause mortality, and new-onset atrial fibrillation.

"These findings highlight AMR as a simple and feasible tool for long-term prognostic management in TAVR patients," they concluded.

Reference: https://doi.org/10.1161/JAHA.124.03934