Trial design and rationale of TY-51924 as a novel Na+/H+ exchanger inhibitor in patients with ST-elevation acute myocardial infarction undergoing percutaneous coronary intervention

Myocardial salvage after ST-segment-elevation myocardial infarction: comparison between prasugrel and clopidogrel in the presence or absence of high-residual platelet reactivity

BACKGROUND

The effect of prasugrel over clopidogrel on myocardial salvage in ST-segment-elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (p-PCI) is not fully elucidated.

METHODS

Among 854 consecutive STEMI patients who underwent p-PCI, 446 patients were evaluated by two-phase (7 days and 3 months) single-photo emission computed tomography (SPECT). Patients were divided into two groups based on the loading P2Y12 inhibitor. The clopidogrel group was further divided based on the result of platelet function testing. Thus, the prasugrel group included 227 patients; the clopidogrel without high-residual platelet reactivity (HRPR) group, 109 patients; and the clopidogrel with HRPR group, 107 patients. The primary endpoint was the Myocardial Salvage Index (MSI), determined by SPECT.

RESULTS

The incidence of final TIMI 0/1 and TIMI myocardial perfusion grade 0/1 was higher in the clopidogrel with HRPR group (0.9%, 1.8%, and 7.5%, P =  .002; 19.8%, 29.4%, and 41.1%, P = .0002, in the prasugrel, clopidogrel without HRPR, and clopidogrel with HRPR groups, respectively). The MSI was significantly lower in the clopidogrel with HRPR group (48% [27-66], 44% [30-72], and 36% [15-55], P =  .006, respectively).

CONCLUSIONS

Prasugrel in STEMI patients was associated with an increased MSI compared with clopidogrel in the presence of HRPR.

Randomized controlled trial of TY-51924, a novel hydrophilic NHE inhibitor, in acute myocardial infarction

BACKGROUND

In patients with ST-elevation acute myocardial infarction (STEMI), reperfusion therapy limits infarct size, but can directly evoke myocardial reperfusion injury. Activation of the Na(+)/H(+) exchanger (NHE) plays an important role in reperfusion injury. TY-51924, a novel NHE inhibitor, significantly reduced infarct size in animal studies and was well tolerated in early-phase clinical trials. This study aim was to evaluate the efficacy and safety of TY-51924 in patients with STEMI.

METHODS

In this multicenter, randomized, double-blind, placebo-controlled Phase II trial, 105 patients with first anterior STEMI undergoing primary percutaneous coronary intervention (pPCI) were randomly assigned to receive an intravenous infusion of either TY-51924 or placebo. Primary endpoints were myocardial salvage index (MSI) as determined by single photon emission computed tomography (SPECT) 3-5 days after pPCI and safety up to 7 days.

RESULTS

Baseline characteristics were similar in the two groups. MSI 3-5 days after pPCI (0.200 vs. 0.290, p=0.56), 3 months after pPCI (0.470 vs. 0.500, p=0.76), and the incidences of side effects did not differ between the two groups as a whole. However, on post hoc analysis of 52 patients with a large area at risk (AAR) (≥38%) and no antegrade coronary flow, MSI by SPECT at 3 months after pPCI was significantly higher in TY-51924 group (0.450 vs. 0.320, p=0.03). TY-51924 did not adversely influence hemodynamics.

CONCLUSIONS

TY-51924 did not improve MSI or increase side effects as a whole. However, TY-51924 is potentially cardioprotective in the presence of a large AAR and no antegrade coronary flow.

Relationship between QRS score and microvascular obstruction after acute anterior myocardial infarction

BACKGROUND

The QRS score on electrocardiogram (ECG) in patients with myocardial infarction (MI) reportedly reflects the severity of myocardial damage. The presence of microvascular obstruction (MO) assessed by cardiac magnetic resonance (CMR) imaging is associated with irreversible myocardial damage. MO assessed by CMR is known to be a predictor for adverse clinical outcome after ST-elevation MI. The aim of the present study was to examine the relationship between QRS score and MO in acute anterior MI patients.

METHODS

Sixty-two patients with first acute anterior MI who successfully underwent primary percutaneous coronary intervention (PCI) were enrolled. The QRS score after PCI on admission ECG was calculated by a Selvester-Wagner QRS scoring system. CMR imaging was performed at 11.4±3.9 days after MI. MO was defined as delayed enhancement with contrast-devoid core. Patients were divided into two groups as follows: 37 patients who showed MO (MO group) and 25 patients who did not show it (non-MO group).

RESULTS

The QRS score was significantly greater in the MO group than in the non-MO group. The QRS score significantly correlated with MO volume (r=0.418, p=0.010). Multivariate analysis showed that the QRS score (odds ratio 1.362, 95% CI: 1.038-1.951, p=0.024) and the peak creatine kinase levels (odds ratio 1.001, 95% CI: 1.000-1.002, p<0.001) were independent predictors for MO.

CONCLUSIONS

Our results indicate that the QRS score derived from simple and widely available ECG may be a useful parameter for assuring the presence of MO.

Imaging in drug development

Imaging has played an important part in the diagnosis of disease and development of the understanding of the underlying disease mechanisms and is now poised to make an impact in the development of new pharmaceuticals. This chapter discusses the underlying technologies that make the field ready for this challenge. In particular, the potentials of magnetic resonance imaging and functional magnetic resonance imaging are outlined, including the new methods developed to provide additional information from the scans carried out. The field of nuclear medicine has seen a rapid increase in interest as advances in radiochemistry have enabled a wide range of new radiotracers to be synthesised.