Validation of dual atrioventricular nodal physiology in dual atrioventricular nodal non-reentrant tachycardia via adenosine triphosphate injection during atrial pacing: A novel insight into the role of leftward inferior extension.

INTRODUCTION: Dual atrioventricular nodal non-reentrant tachycardia (DAVNNT) is a rare and challenging-to-diagnose arrhythmia, without previous reports associating it with a leftward inferior extension (LIE). METHODS: Diagnosis was made using adenosine triphosphate (ATP) injection during atrial pacing in a suspected DAVNNT patient. RESULTS: Ablation of the rightward inferior extension was unsuccessful in eliminating DAVNNT; however, subsequent ablation of the LIE successfully eradicated the arrhythmia. CONCLUSION: This unique case, marked by the first instance of DAVNNT caused by LIE, diagnosed through ATP injection, underscores the utility of this diagnostic approach and broadens the spectrum of our understanding and management of this condition.

Prognostic Value of Coronary Sinus Flow Quantification by Cardiac Magnetic Resonance Imaging in Patients With Acute Myocardial Infarction.

Background This study aimed to evaluate the prognostic value of hyperemic coronary sinus flow (h-CSF) and global coronary flow reserve (g-CFR) obtained by phase-contrast cine-magnetic resonance imaging in patients with acute myocardial infarction (MI). Methods and Results This retrospective study analyzed patients with acute MI (n=523) who underwent primary (ST-segment-elevation MI) or urgent (non-ST-segment-elevation MI) percutaneous coronary intervention. Absolute coronary sinus blood flow (CSF) at rest and during vasodilator stress hyperemia was quantified at 30 days (24-36 days) after the index infarct-related lesion percutaneous coronary intervention and revascularization of functionally significant non-infarct-related lesions. We used Cox proportional hazards regression modeling to examine the association between h-CSF, g-CFR, and major adverse cardiac events defined as all-cause death, nonfatal MI, hospitalization for congestive heart failure, and stroke. Finally, 325 patients with ST-segment-elevation MI (62.1%) and 198 patients with non-ST-segment-elevation MI (37.9%) were studied over a median follow-up of 2.5 years. The rest CSF, h-CSF, and g-CFR were 0.94 (0.68-1.26) mL/min per g, 2.05 (1.42-2.73) mL/min per g, and 2.17 (1.54-3.03), respectively. Major adverse cardiac events occurred in 62 patients, and Cox proportional hazards analysis showed that h-CSF and g-CFR were independent predictors of major adverse cardiac events (h-CSF: hazard ratio [HR], 0.64; 95% CI, 0.47-0.88; P=0.005; g-CFR: HR, 0.62; 95% CI, 0.47-0.82; P=0.001). When stratified by h-CSF and g-CFR, cardiac event-free survival was the worst in patients with concordantly impaired h-CSF (<1.6 mL/min per g) and g-CFR (<1.7) (P<0.001). Conclusions Global coronary sinus flow quantification using phase-contrast cine-magnetic resonance imaging provided significant prognostic information independent of infarction size and conventional risk factors in patients with acute MI undergoing revascularization.

Effect of percutaneous coronary intervention on global hemodynamics and the prevalence of residual microvascular dysfunction.

OBJECTIVES: We aimed to examine the changes in hyperemic coronary sinus flow (CSF) and global coronary flow reserve (g-CFR) after percutaneous coronary intervention (PCI) and investigate the predictors to improve these metrics and the prevalence of residual coronary microvascular dysfunction (CMD). METHODS: This prospective, single-center study included 118 patients with stable coronary artery disease undergoing PCI for a single proximal lesion. Phase-contrast cine-cardiac magnetic resonance (PC-CMR) was used to assess hyperemic CSF (HCSF) and g-CFR, before and after PCI. Residual CMD was defined as concordantly impaired post-PCI HCSF (<2.3 ml/min/g) and g-CFR (<2.0). RESULTS: HCSF significantly increased, although 38 (32.2%) patients showed a decrease. There was no significant change in g-CFR despite fractional flow reserve (FFR) improvement in all target territories. Concordantly increased HCSF and g-CFR were effectively discriminated by adding PC-CMR-derived information to pre-PCI FFR. Residual CMD was observed in 30 (25.4%) patients and was associated with pre-PCI renal dysfunction and lower pre-PCI rest and hyperemic CSF, but not with pre-PCI regional physiological indices. CONCLUSIONS: FFR-guided PCI was associated with increased HCSF, but not with increased g-CFR. After uncomplicated PCI, one-quarter of patients showed residual CMD. Our approach may help identify patients who may benefit from increased coronary perfusion or show residual CMD.

Effect of contrast medium versus low-molecular-weight dextran for intracoronary optical coherence tomography in renal insufficiency.

Low-molecular-weight dextran (LMWD) is considered a safe alternative to contrast media to displace blood during optical coherence tomography (OCT) imaging, but concerns remain. The purpose of this study was to investigate whether using LMWD for OCT protects against kidney injury in patients with renal insufficiency compared with contrast media. We retrospectively identified 474 patients with renal insufficiency (estimated glomerular filtration rate < 60 ml/min/1.73 m2) who underwent OCT during coronary angiography or percutaneous coronary intervention; 110 patients with LMWD plus contrast medium (LMWD group) and 364 patients with contrast medium exclusively (Contrast group). We evaluated differences between the two groups and performed propensity score-matched subgroup comparisons. Compared with the Contrast group, the LMWD group had worse baseline renal function, higher prevalence of diabetes mellitus and percutaneous coronary intervention history, higher C-reactive protein and N-terminal pro B-type natriuretic peptide levels, lower hemoglobin levels, and lower left ventricular ejection fraction. The median total volume of contrast medium in the Contrast group was 230.0 ml vs. 61.8 ml of LMWD in addition to 164.0 ml of contrast medium in the LMWD group. Renal function was consistently impaired in the LMWD group within 5 days, at 1-month, and 1-year follow-up (P < 0.001). Two propensity score-matched analyses adjusted for either total volume used or contrast media volume consistently indicated a trend toward worsening renal function in the LMWD group at the 1-year follow-up. No protective benefit for renal function from using LMWD instead of contrast media for OCT was observed in patients with renal insufficiency.