Application of AMR in evaluating microvascular dysfunction after ST-elevation myocardial infarction.

BACKGROUND: A guidewire-free angiography-derived microcirculatory resistance (AMR) derived from Quantitative flow ratio (QFR) exhibits good diagnostic accuracy for assessing coronary microvascular dysfunction (CMD), but there are no relevant studies supporting the specific application of AMR in patients with ST-elevation myocardial infarction (STEMI). The study aims to evaluate CMD in patients with STEMI using the AMR index. METHODS: This study included patients with STEMI who underwent percutaneous coronary intervention (PCI) from June 1, 2020 to September 28, 2021. All patients were divided into two groups: the CMD (n = 215) and non-CMD (n = 291) groups. After matching, there were 382 patients in both groups.1-year follow-up major adverse cardiac events (MACEs) were evaluated. RESULTS: After matching, the primary endpoint was achieved in 41 patients (10.7%), with 27 and 14 patients in the CMD and non-CMD groups, respectively (HR 1.954 [95% CI 1.025-3.726]; 14.1% versus 7.3%, p = .042). Subgroup analysis revealed that 18 patients (4.7%) were readmitted for heart failure, with 15 and 3 in the CMD and non-CMD groups, respectively (HR 5.082 [95% CI 1.471-17.554]; 7.9% versus 1.6%, p = .010). Post-PCI AMR ≥ 250 was significantly associated with a higher risk of the primary endpoint and was its independent predictor (HR 2.265 [95% CI 1.136-4.515], p = .020). CONCLUSION: The retrospective use of AMR with a cutoff value of ≥250 after PCI in patients with STEMI can predict a significant difference in the 1-year MACE rates when compared with a propensity score-matched group with normal AMR.

Mechanism of contractile dysfunction induced by serotonin in coronary artery in spontaneously hypertensive rats.

Hypertension is one of the risk factors for coronary heart disease. The present study investigated the mechanism of contractile dysfunction induced by serotonin (5-HT) in coronary artery in spontaneously hypertensive rats (SHRs). Coronary arteries were isolated form SHRs and Wistar rats. Arterial ring contraction was measured using a multi myograph system. Intracellular calcium concentration was measured with a Ca2+ probe fluo-4/AM in vascular smooth muscle cells (VSMCs) isolated from coronary arteries. Signaling pathway-related proteins were assayed by western blotting. A 5-HT2A receptor blocker, sarpogrelate, completely eliminated coronary artery contraction induced by 5-HT. PLCß inhibitor U73122 also significantly inhibited the response to 5-HT. Compared with the Wistar rats, serotonin (5-HT)- and CaCl2-induced coronary vasoconstriction in the SHRs was significantly reduced. Rho-associated protein kinase inhibitor Y27632, PKC inhibitor rottlerin, and L-type calcium channel blocker nifedipine inhibited the 5-HT-induced coronary artery contraction in a dose-dependent manner in SHRs and Wistar rats. However, the inhibitory effects were reduced in SHRs. In addition, store-operated Ca2+ (SOC) induced an obvious Ca2+ influx in coronary arterial smooth muscle cells, whereas SOC-mediated contraction was very slight in coronary arteries. At the same time, it was found that 5-HT2AR, IP3R, and Cav1.2 protein expression and PKCδ activity were decreased, and STIM1 and Orai1 were increased in VSMCs from coronary arteries of SHRs compared with Wistar rats. These results implicate calcium-handling dysfunction mediated by the 5-HT2A receptor and downstream signaling pathway might lead to a reduction in 5-HT-induced contraction in SHR coronary arteries.

Modified shock index is a predictor for 7-day outcomes in patients with STEMI.

SUBJECT: The aim of this study was to compare the predictive values of modified shock index (MSI) and shock index (SI) for 7-day outcome in patients with ST-segment elevation myocardial infarction (STEMI). METHODS: This retrospective study included 160 consecutive patients with STEMI and emergency percutaneous coronary intervention. The blood pressure (BP) and heart rate (HR) measured at emergency department were used to calculate SI (HR/systolic BP) and MSI (HR/mean artery pressure). The major adverse cardiac events (MACE) included all-cause mortality, life-threatening arrhythmias, cardiogenic shock, and Killip class within 7 days. RESULTS: Forty-nine patients had increased MSI (≥1.4), whereas 72 had increased SI (≥0.7). Except the parameters on BP and HR, other parameters were similar between the normal and increased SI groups. However, the increased MSI group had significantly higher age (69.0 ± 13.0 years vs 63.9 ± 12.9 years, P = .025) than the normal MSI group. The 7-day all-cause mortality was 8.8%, and MACE rate was 24.4% in this study. Both increased SI and increased MSI predicted higher MACE rates. However, the odds ratios of increased MSI for all-cause mortality (6.8 vs 3.4), cardiogenic shock (3.0 vs 1.6), life-threatening arrhythmias (9.1 vs 4.6), and MACE (6.8 vs 3.4) were higher than those of increased SI. Modified shock index and SI were independent factor for MACE, but the odds ratio of MSI was higher than of SI (3.05 vs 1.07). CONCLUSIONS: Both SI and MSI in emergency department could predict the all-cause mortality and MACE rates within 7 days in patients with STEMI, but MSI may be more accurate than SI.