Coronary microvascular dysfunction in patients undergoing transcatheter aortic valve implantation: A systematic review and meta-analysis.
Maethas Panyawongkhanti, Peerawat Chintrakulchai, Chonthicha Tanking et al.
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In 30 seconds
This systematic review and meta-analysis examined coronary microvascular dysfunction (CMD) in adults with severe aortic stenosis undergoing transcatheter aortic valve implantation (TAVI). Eleven primary studies were included; 10 contributed to prevalence analyses. Pooled CMD prevalence differed by assessment method: 46.8% with wire-based thermodilution and 38.4% with angiographic indices. In five studies, coronary flow reserve increased after TAVI by a pooled mean difference of +0.49 (95% CI [+0.27, +0.71]). The association between baseline CMD and major adverse cardiovascular events (MACE) was uncertain and considered hypothesis-generating.
Key findings
- CMD prevalence was 46.8% (95% CI [34.0, 59.9]; I2 = 72%) with wire-based thermodilution and 38.4% (95% CI [35.3, 41.7]; I2 = 0%) with angiographic indices.
- After TAVI, coronary flow reserve increased by a pooled mean difference of +0.49 (95% CI [+0.27, + 0.71]; I2 = 72%; k = 5, n = 103 paired observations).
- The pooled hazard ratio for MACE with baseline CMD was 3.22 (95% CI [0.98, 10.60]; I2 = 78%; k = 2, n = 585), with substantial uncertainty.
- Absolute minimal microvascular resistance was unchanged; reductions were reported only for pressure-to-velocity and reserve ratio indices.
Why it matters
CMD appears common before TAVI, but its estimated prevalence depends on the diagnostic method, complicating comparisons across studies and interpretation of individual measurements. The observed post-procedure rise in coronary flow reserve suggests that microvascular indices may change after valve intervention, while the uncertain MACE association does not establish prognostic value. Standardized assessment is needed to clarify these findings.
What to keep in mind
The evidence was heterogeneous, CMD definitions varied, and the MACE estimate came from only two studies with incompatible hazard-ratio calculations. The authors describe the prognostic association as hypothesis-generating.