The role of arginine vasopressin in the pathophysiology of microvascular dysfunction after ST-elevation myocardial infarction
Authors: Alatta A , Das R , Mohammed A , Spray L , Purcell I , Spyridopoulos I 
Published: November 2023

Abstract

Background
Coronary microvascular dysfunction (CMD) after ST-elevation myocardial infarction (STEMI), in part due to impaired vasomotor tone, predicts heart failure and mortality at one year. Arginine vasopressin (AVP) may be implicated in CMD as it is released during MI and has known vasoconstrictor effects, but data in humans are lacking. We examined the role of copeptin, a stable plasma surrogate marker of AVP, in humans with STEMI.

Methods
We included three cohorts. The first cohort prospectively recruited patients presenting with STEMI eligible for primary percutaneous coronary intervention (PPCI) (n= 55). In this cohort, the index of microcirculatory resistance (IMR) and coronary flow reserve (CFR) were measured in the culprit artery at the end of the procedure. The second cohort included 45 patients from a sub-study of the CAPRI trial (Evaluating the effectiveness of intravenous Ciclosporin on reducing reperfusion injury in pAtients undergoing PRImary PCI; NCT02390674). In this cohort, patients underwent cardiac magnetic resonance (CMR) imaging at one and 12 weeks post-MI, allowing precise measurement of infarct size and microvascular obstruction (MVO), the imaging hallmark of CMD. Both cohorts had serum copeptin measured at four time points. The 3rd cohort included two patients undergoing trans-coronary alcohol ablation of septal hypertrophy (TASH). Serial copeptin measurements were performed in this cohort to assess copeptin release in an induced ischaemia setting.

Results
One hundred patients were included from both STEMI cohorts. Copeptin levels paralleled AVP plasma levels closely, with mean levels falling in the 24 hours after reperfusion from 92.5 pmol/L to 6.4 pmol/L, and this was mirrored in the TASH patients. Copeptin release wasinversely linked to admission diastolic blood pressure (DBP) (Spearman’s rho r= -0.431, p=0.001), but did not correlate with systolic blood pressure. Copeptin levels at 24 hours were significantly associated with high IMR (r=0.372, p=0.011) and low CFR (r=-0.467, p=0.001). Patients with IMR &gt;40 also had significantly higher mean copeptin concentration at 24 hours than those with lower IMR (19.1 vs 7.1pmol/L, p=0.019, Figure 1). Finally, patients with MVO on early CMR showed a trend towards higher mean copeptin concentration at baseline, although this was not statistically significant. Notably, copeptin levels were not associated with infarct size on either early or late CMR.

Conclusions
Copeptin, and therefore AVP, is released secondary to acute myocardial ischaemia, particularly in response to reduced coronary perfusion, as evidenced by the inverse correlation with DBP, and normalises by 24 hours. However, evidence of CMD was seen in patients with persistently elevated copeptin at 24 hours, suggesting AVP may contribute to microcirculatory dysfunction. AVP receptor antagonists may represent a novel therapeutic option in patients with STEMI and evidence of microvascular dysfunction.