Endothelium and blood flow mediated vasomotion in the conscious dog

Risk Factors of Periprocedural Bradycardia during Primary Percutaneous Coronary Intervention in Patients with Acute ST-Elevation Myocardial Infarction

Background

Evidence available suggests that periprocedural bradycardia negates the benefit of primary percutaneous coronary intervention (PPCI) and worsens the prognosis of patients with acute ST-elevation myocardial infarction (STEMI).

Objective

To investigate the risk factors of periprocedural bradycardia during PPCI in patients with acute STEMI.

Methods

We enrolled 2,536 acute STEMI patients who had PPCI from November 2007 to June 2018 in Beijing Anzhen Hospital, Capital Medical University. We divided all patients into two groups according to periprocedural bradycardia (preoperative heart rate ≥50 times/min, intraoperative heart rate <50 times/min persistent or transient) during PPCI: periprocedural bradycardia group (434 cases) and control group (2102 cases). We compared demographic, clinical, and angiographic characteristics of the two groups. We analyzed the risk factors of periprocedural bradycardia.

Results

The incident rate was 17.1% (434/2536). Logistic regression analysis showed that the differences between the two groups in no-reflow, the culprit vessel was LAD, using thrombus aspiration devices during operation, gender, completely block of culprit vessel, and intraoperative hypotension were statistically significant (P < 0.05). The area under the receiver operating characteristic curve was 0.8390.

Conclusions

No-reflow, the culprit vessel was not LAD, using thrombus aspiration devices during operation, gender, completely block of culprit vessel, and intraoperative hypotension may be independent risk factors for predicting periprocedural bradycardia during PPCI in patients with acute STEMI. We registered this study with WHO International Clinical Trials Registry Platform (ICTRP) (registration number: ChiCTR1900023214; registered date: 16 May 2019).

Cyclic GMP-independent relaxation and hyperpolarization with acetylcholine in guinea-pig coronary artery

1. The effects of acetylcholine (ACh) on membrane potential, relaxation and cyclic GMP levels were compared to the NO donor L-nitrosocysteine (Cys-NO) in segments of guinea-pig coronary artery. 2. ACh and Cys-NO produced concentration-dependent relaxations of muscles contracted with the H1 receptor agonist, 2-(2-aminoethyl)pyridine (AEP, 0.35 mM). The relaxation to ACh was unchanged in the presence of NG-monomethyl-L-arginine (L-NMMA; 350 microM) or indomethacin (3 microM). 3. Oxyhaemoglobin (HbO; 20 microM) alone or in combination with L-NMMA increased the EC50 for ACh-induced relaxation whereas relaxation with Cys-NO was almost completely abolished with HbO. 4. Scorpion venom (SV; 8.7 micrograms ml-1) increased the EC50 for relaxation with ACh but not Cys-NO. Combined L-NMMA, HbO and SV produced nearly complete abolition of ACh-induced relaxations. 5. Basal cyclic GMP levels (i.e., 20 pmol mg-1 protein) were significantly increased following addition of either ACh (190 pmol mg-1 protein) or Cys-NO (240 pmol mg-1 protein). L-NMMA significantly reduced the rise of cyclic GMP with ACh but not Cys-NO. In contrast, SV did not significantly reduce the rise in cyclic GMP produced with ACh. In the combined presence of L-NMMA and HbO neither ACh nor Cys-NO produced a significant increase in cyclic GMP levels. 6. ACh gave rise to significantly greater membrane hyperpolarization than Cys-NO both in the presence and absence of AEP. Combined L-NMMA and HbO did not reduce the amplitude of hyperpolarization with ACh. 7. These data indicate that some but not all of the actions of ACh in the coronary artery can be mimicked by the NO donor, Cys-NO, suggesting that ACh releases NO as well as a second hyperpolarizing factor (i.e., EDHF). Release of NO results in a large increase in tissue cyclic GMP levels and minimal change in membrane potential whereas release of EDHF results in a large membrane hyperpolarization which is independent of changes in tissue cyclic GMP levels. Both of these pathways appear to contribute to relaxation throughout the entire ACh concentration-relaxation relationship.