Relationship of plasma neuropeptide Y with angiographic, electrocardiographic and coronary physiology indices of reperfusion during ST elevation myocardial infarction

Abstract

Objectives: The co-transmitter neuropeptide Y (NPY) is released during high levels of sympathetic stimulation and is a potent vasoconstrictor. We defined the release profile of plasma NPY during acute ST elevation myocardial infarction, and tested the hypothesis that levels correlate with reperfusion measures after treatment with primary percutaneous coronary intervention (PPCI).

Design: Prospective observational study.

Setting: University hospital heart centre.

Patients: 64 patients (62.6±11.7 years-old, 73% male) presenting throughout the 24-h cycle of clinical activity with ST elevation myocardial infarction.

Interventions: PPCI.

Main outcome measures: NPY was measured (ELISA) in peripheral blood taken before and immediately after PPCI and at 6, 24 and 48 h post-PPCI. Reperfusion was assessed by angiographic criteria, ST segment resolution, invasive measurement of coronary flow reserve and the index of microcirculatory resistance.

Results: Plasma NPY levels were highest before PPCI (17.4 (8.8-42.2) pg/ml, median (IQR)) and dropped significantly post-PPCI (12.4 (6.5-26.7) pg/ml, p<0.0001) and after 6 h (9.0 (2.6-21.5) pg/ml, p=0.008). Patients with admission NPY levels above the median were significantly more hypertensive and tachycardic and were more likely to have diabetes mellitus. Patients with angiographic no-reflow (less than thrombolysis in myocardial infarction 3 flow and myocardial blush grade >2, n=16) or no electrocardiographic ST resolution (<70%, n=30) following PPCI had significantly higher plasma NPY levels. Patients with a coronary flow reserve <1.5 or index of microcirculatory resistance >33 also had significantly higher plasma NPY levels pre-PPCI and post-PPCI.

Conclusions: Plasma NPY levels correlate with indices of reperfusion and coronary microvascular resistance.

Figure 1

Evolution of plasma neuropeptide Y (NPY) levels over the first 48 h of ST elevation myocardial infarction treated by primary percutaneous intervention (PPCI). Raw data shown with medians (horizontal line) and the IQR. NPY values dropped significantly in the first 6 h (pre-PPCI vs post-PPCI, p<0.001; post-PPCI vs 6 h, p=0.008) but stayed stable thereafter (6 h vs 24 h, p=0.91, 24 h vs 48 h, p=0.88).

Figure 2

Plasma neuropeptide Y (NPY) levels (mean values, bars representing the SE of mean) according to resolution of ST elevation and angiographic reflow. NPY values between angiographic reflow/no-reflow and resolution/no resolution of the ST segment were compared using non-parametric testing (Mann-Whitney).

Figure 3

Plasma neuropeptide Y (NPY) levels (mean values, bars representing the SE of mean) according to median coronary flow reserve and median index of microvascular resistance. NPY values between CFR <1.5/>1.5 and IMR <33/>33 compared using non-parametric testing (Mann-Whitney). PPCI. primary percutaneous intervention.

Figure 4

Log plasma neuropeptide Y (NPY) levels according to tertiles of myocardial infarction size. Infarct size was assessed using log area under the curve (AUC) troponin (AUC from following measurements: pre-primary percutaneous intervention (PPCI), post-PPCI, 6 h, 24 h and 48 h). Log NPY values were compared using ANOVA (p=0.04) and the differences between the groups were evaluated using Bonferroni post hoc analysis.