Prognostic value of microvascular resistance index immediately after primary percutaneous coronary intervention on left ventricular remodeling in patients with reperfused anterior acute ST-segment elevation myocardial infarction.

OBJECTIVES: This study sought to investigate the relationship between the degree of microvascular dysfunction assessed by a dual-sensor guidewire (pressure and Doppler velocity) and left ventricular (LV) remodeling after successful primary percutaneous coronary intervention (PPCI) for a first anterior acute myocardial infarction (AMI).

BACKGROUND: Microvascular dysfunction after AMI is associated with progressive LV dilation.

METHODS: In 24 consecutive patients, the microvascular resistance index (MVRI) immediately after PPCI was calculated as the ratio of the mean distal pressure to average peak flow velocity during maximal hyperemia. Cardiac magnetic resonance was performed to determine LV volumes at baseline and 8-month follow-up. LV remodeling was defined as an increase in left ventricular end-diastolic volume (LVEDV) of ≥20%.

RESULTS: In patients with an MVRI greater than the median value of 2.96 mm Hg·cm(-1)·s, the LVEDV increased significantly from 117.1 ± 20.7 ml at baseline to 146.5 ± 21.4 ml (p = 0.006) at 8 months, whereas it did not change between baseline and 8 months (108.2 ± 21.2 ml vs. 111.6 ± 29.9 ml, p = 0.620) in patients with an MVRI ≤2.96 mm Hg·cm(-1)·s. LV remodeling was more frequent in the group with an MVRI >2.96 mm Hg·cm(-1)·s (64% vs. 15%, p = 0.033). Furthermore, there was a positive correlation between MVRI and the percentage of increase or decrease in LVEDV (r = 0.42, p = 0.042). Logistic regression analysis showed that MVRI was the strongest univariate predictor of LV remodeling. The best cutoff value of MVRI was 2.96 mm Hg·cm(-1)·s with a sensitivity of 78% and a specificity of 73%.

CONCLUSIONS: MVRI immediately after PPCI predicts LV remodeling in patients with reperfused anterior AMI.