International Journal of Cardiology

International Journal of Cardiology | Vol. 10, No. 7, July 2019 | pp. 49–56

DOI: 10.46882/2019/IJC/000124

Original Research Article

Diagnostic Precision of High-Resolution 3D Late Gadolinium Enhancement CMR for the Identification of Left Atrial Conduction Gaps Post-Cryoballoon Ablation

David M. Ross¹, Sarah L. Jenkins¹, Richard G. Carter²

¹Department of Cardiovascular Imaging, The Alfred Hospital, Monash University, Melbourne, Victoria, Australia

²Division of Electrophysiology, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia

Abstract:
Cryoballoon catheter ablation successfully isolates the pulmonary veins in paroxysmal atrial fibrillation (AF), but recurrent tachyarrhythmias arise if incomplete scar sets leave linear conduction gaps. Non-invasive mapping of thin left atrial (LA) scars requires optimized high-spatial-resolution sequencing to plan revision procedures. This study evaluated the diagnostic precision of high-resolution 3D late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) for identifying pulmonary vein scar discontinuity, using electroanatomical voltage mapping (EAM) as the reference standard. We prospectively evaluated 52 patients with recurrent atrial tachyarrhythmias scheduled for a secondary ablation procedure who underwent pre-procedural 3D LGE CMR (1.3 mm isotropic voxel size). Left atrial walls were segmentally partitioned and thresholded to isolate scars at 3 standard deviations above healthy tissue. Segmental scar footprints were registered into intraprocedural 3D EAM matrices. On a segment-by-segment analysis (416 total sections), high-resolution 3D LGE CMR identified conduction gaps with a sensitivity of 86.4% (95% CI: 77.2%–92.8%), a specificity of 89.6% (95% CI: 82.3%–94.7%), and an overall diagnostic accuracy of 88.5%. The total computed circumference of circumscribed PVI scar patterns matched low-voltage areas on EAM maps (r = 0.82, p < 0.001). No severe contrast-related side effects were reported. High-resolution isotropic 3D late gadolinium enhancement CMR demonstrates excellent diagnostic precision for identifying left atrial scar gaps, offering a robust non-invasive method to localize conduction breaches prior to repeat ablation interventions.

Keywords: Atrial fibrillation, Cryoballoon ablation, Cardiac magnetic resonance, Late gadolinium enhancement, Left atrium, Electroanatomical mapping

Received: April 02, 2019; Revised: May 15, 2019; Accepted: June 08, 2019; Published: July 22, 2019

International Journal of Cardiology | Vol. 10, No. 3, March 2019 | pp. 17–24

DOI: 10.46882/2019/IJC/000120

Original Research Article

Diagnostic Utility of Non-Invasive FFR-CT for Ischemia Detection in Patients with High Coronary Calcium Scores

Arjun Patel¹, Rohan Mehta¹, Vikram Singh²

¹Department of Cardiology, Post Graduate Institute of Medical Education and Research, Chandigarh, India

²Division of Cardiovascular Radiology, All India Institute of Medical Sciences, New Delhi, India

Abstract:
Computed tomography coronary angiography (CTCA) exhibits limited diagnostic specificity in patients with heavy coronary calcification due to blooming artifacts that obscure luminal narrowings. Fractional flow reserve computed from CTCA datasets (FFR-CT) integrates computational fluid dynamics to evaluate lesion-specific ischemia non-invasively. This study evaluated the diagnostic accuracy of FFR-CT for identifying lesion-specific ischemia specifically in patients with high coronary artery calcium (CAC) scores. We prospectively enrolled 110 symptomatic patients with intermediate coronary stenoses and an Agatston CAC score greater than 400 who were scheduled for invasive coronary angiography and fractional flow reserve (FFR). FFR-CT was computed off-line using specialized processing software. Ischemia was defined as an invasive FFR less than or equal to 0.80. On a vessel-based analysis (134 vessels total), invasive FFR confirmed lesion-specific ischemia in 42 vessels (31.3%). FFR-CT demonstrated a diagnostic sensitivity, specificity, positive predictive value, and negative predictive value of 85.7% (95% CI: 71.5%–94.6%), 81.5% (95% CI: 72.1%–88.9%), 67.9% (95% CI: 53.7%–80.1%), and 92.6% (95% CI: 84.6%–97.2%), respectively. The area under the receiver operating characteristic curve for FFR-CT was significantly superior to standard anatomical CTCA luminal assessment alone (0.87 vs. 0.64, p < 0.01). FFR-CT maintains high diagnostic accuracy and strong negative predictive value for identifying hemodynamically significant coronary stenoses even in the presence of severe calcification.

Keywords: Computed tomography coronary angiography, Fractional flow reserve, Coronary calcification, Computational fluid dynamics, Myocardial ischemia, Diagnostic accuracy

Received: December 05, 2013; Revised: January 18, 2014; Accepted: February 11, 2014; Published: March 20, 2019

International Journal of Cardiology | Vol. 10, No. 2, February 2019 | pp. 9–16

DOI: 10.46882/2019/IJC/000119

Original Research Article

Two-Dimensional Global Longitudinal Strain for Long-Term Risk Assessment in Light-Chain Cardiac Amyloidosis

Sven Lindstrom¹, Ingrid Johansson¹, Anders Nielsen²

¹Department of Cardiology, Karolinska University Hospital, Stockholm, Sweden

²Department of Clinical Physiology, Aarhus University Hospital, Aarhus, Denmark

Abstract:
Light-chain (AL) cardiac amyloidosis is characterized by progressive extracellular amyloid fibril deposition, leading to restrictive cardiomyopathy and severe heart failure. Early recognition of myocardial involvement is essential, as conventional metrics like LVEF often remain preserved until advanced stages. This study evaluated the long-term prognostic value of speckle-tracking derived global longitudinal strain (GLS) and the relative apical sparing pattern in patients with biopsy-proven AL amyloidosis. We prospectively followed 85 patients with systemic AL amyloidosis. All patients underwent comprehensive baseline echocardiography with off-line speckle-tracking deformation imaging. The primary endpoint was all-cause mortality over a 3-year follow-up period. Myocardial involvement was defined by standard extracellular volume metrics and wall thickness. An absolute baseline GLS less than 14.5% was identified in 64.7% of the cohort. Classic apical sparing, characterized by a preserved apical strain with severely reduced basal and mid-ventricular segment deformation, was present in 52.9% of patients. Over a median follow-up of 28 months, 32 patients (37.6%) died. Kaplan-Meier survival curves showed significantly worse survival in patients with a baseline absolute GLS less than 14.5% (log-rank p < 0.001). Multivariable Cox proportional hazards regression confirmed that baseline GLS was a potent, independent predictor of 3-year all-cause mortality (hazard ratio: 1.24 per 1% absolute reduction, 95% CI: 1.11–1.38, p < 0.001), outperforming traditional biomarkers like NT-proBNP and high-sensitivity troponin T. Two-dimensional global longitudinal strain is a powerful independent predictor of mortality in light-chain cardiac amyloidosis, serving as a critical tool for early risk stratification.

Keywords: Cardiac amyloidosis, Light-chain amyloidosis, Echocardiography, Global longitudinal strain, Apical sparing, Prognosis

Received: November 08, 2013; Revised: December 20, 2013; Accepted: January 12, 2014; Published: February 22, 2019

International Journal of Cardiology | Vol. 10, No. 5, May 2019 | pp. 33–40

DOI: 10.46882/2019/IJC/000122

Original Research Article

SGLT2 Inhibition with Dapagliflozin Mitigates Myocardial Infarct Size and Attenuates Adverse Left Ventricular Remodeling in a Rat Model of Ischemia-Reperfusion Injury

Heinrich Scholz¹, Klaus Richter¹, Manfred Ziegler²

¹Department of Cardiovascular Pharmacology, University Heart Center Freiburg, Freiburg, Germany

²Division of Experimental Cardiology, Max Delbrück Center for Molecular Medicine, Berlin, Germany

Abstract:
Sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce cardiovascular death and heart failure hospitalization in clinical trials, yet the localized cellular pathways driving these benefits immediately after ischemic insults remain unresolved. This study investigated the acute cardioprotective effects of dapagliflozin on myocardial infarct size and structural remodeling in a non-diabetic rat model of ischemia-reperfusion (I/R) injury. Male Sprague-Dawley rats were randomized to receive either dapagliflozin (1.5 mg/kg/day, n = 15) or vehicle control (n = 15) via oral gavage for 14 days before undergoing 30 minutes of left anterior descending coronary artery occlusion followed by 24 hours of reperfusion. Infarct size was determined using triphenyltetrazolium chloride staining, and localized inflammation was evaluated via immunohistochemistry. Pretreatment with dapagliflozin significantly limited myocardial infarct size relative to the vehicle control group (28.4% ± 3.2% vs. 44.2% ± 4.1% of the risk area, p < 0.01). Echocardiography at 24 hours revealed a preservation of left ventricular fractional shortening in the dapagliflozin cohort (28.5% ± 2.4% vs. 21.2% ± 1.9%, p < 0.05). Mechanistically, dapagliflozin-treated rats demonstrated a marked reduction in myocardial tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 expression within the border zone. Western blot analysis confirmed a significant down-regulation of cleaved caspase-3 activation alongside up-regulated AMP-activated protein kinase (AMPK) phosphorylation. Dapagliflozin exerts direct, potent cardioprotective actions against acute ischemia-reperfusion injury in non-diabetic rats by mitigating localized inflammatory cell infiltration and suppressing cardiomyocyte apoptotic cascades through active AMPK pathway modulation.

Keywords: Ischemia-reperfusion injury, Dapagliflozin, SGLT2 inhibitors, Infarct size, Apoptosis, Inflammation

Received: February 14, 2019; Revised: March 28, 2019; Accepted: April 12, 2019; Published: May 22, 2019

International Journal of Cardiology | Vol. 10, No. 12, December 2019 | pp. 89–96

DOI: 10.46882/2019/IJC/000129

Original Research Article

Independent Predictive Value of High-Sensitivity Postoperative Cardiac Troponin T Release for New-Onset Postoperative Atrial Fibrillation

Chloe Jenkins¹, Oliver Vance¹, Sarah E. Lawson²

¹Emergency Department, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia

²School of Medicine, University of Queensland, Brisbane, Queensland, Australia

Abstract:
Postoperative atrial fibrillation (POAF) is the most frequent arrhythmic complication following cardiac surgery, associated with a higher risk of systemic stroke and prolonged hospitalization. While inflammation is a recognized trigger, the role of subclinical periprocedural myocardial injury as an arrhythmogenic substrate requires verification. This prospective observational study evaluated the independent association between early postoperative high-sensitivity cardiac troponin T (hs-cTnT) elevations and the development of new-onset POAF. We enrolled 210 patients in baseline sinus rhythm who underwent elective coronary artery bypass grafting or valvular replacement surgery. Plasma hs-cTnT levels were collected preoperatively and at 12 hours post-surgery. Continuous telemetry tracked cardiac rhythms throughout the hospital stay. New-onset POAF lasting longer than 30 seconds developed in 64 patients (30.5%). Preoperative troponin levels did not differ between the cohorts. However, at 12 hours postoperatively, hs-cTnT concentrations were significantly higher in patients who subsequently developed POAF than in those who remained in sinus rhythm (425.4 ± 84.6 ng/L vs. 284.2 ± 62.1 ng/L, p < 0.001). Multivariable logistic regression revealed that a 12-hour postoperative hs-cTnT level above 350 ng/L was a potent independent predictor of POAF development (odds ratio: 2.34, 95% CI: 1.41–3.88, p = 0.002), after adjusting for surgical parameters and advanced age. Elevated early postoperative high-sensitivity cardiac troponin T release independently predicts new-onset postoperative atrial fibrillation, indicating that subclinical periprocedural myocardial injury serves as a primary driver of postoperative arrhythmogenesis.

Keywords: Atrial fibrillation, Cardiac surgery, High-sensitivity cardiac troponin T, Myocardial injury, Postoperative complications, Arrhythmogenesis

Received: September 15, 2019; Revised: October 28, 2019; Accepted: November 12, 2019; Published: December 19, 2019

International Journal of Cardiology | Vol. 10, No. 10, October 2019 | pp. 73–80

DOI: 10.46882/2019/IJC/000127

Original Research Article

Diagnostic Utility of Computational Fluid Dynamics Derived FFR-CT for Identifying Ischemia-Producing Lesions in Calcified Coronary Arteries

Arjun Patel¹, Rohan Mehta¹, Vikram Singh²

¹Department of Cardiology, Post Graduate Institute of Medical Education and Research, Chandigarh, India

²Division of Cardiovascular Radiology, All India Institute of Medical Sciences, New Delhi, India

Abstract:
Severe coronary artery calcification introduces severe blooming artifacts during computed tomography coronary angiography (CTCA), which limits structural specificity and results in false-positive findings. Fractional flow reserve derived from standard CTCA datasets (FFR-CT) utilizes computational fluid dynamics to evaluate lesion-specific ischemia non-invasively. This multi-center prospective study evaluated the diagnostic performance of FFR-CT for identifying hemodynamically significant lesions in patients with heavy coronary calcification. We enrolled 115 symptomatic patients with an intermediate anatomical coronary stenosis (30% to 70%) and a baseline Agatston coronary artery calcium (CAC) score greater than 400 who were scheduled for invasive coronary angiography and fractional flow reserve (FFR). FFR-CT was processed off-line using specialized fluid dynamics software, with ischemia defined as an FFR-CT less than or equal to 0.80. On a vessel-based analysis (142 vessels total), invasive FFR confirmed lesion-specific ischemia in 45 vessels (31.7%). Non-invasive FFR-CT demonstrated a diagnostic sensitivity of 86.7% (95% CI: 73.2%–94.9%), a specificity of 81.4% (95% CI: 72.3%–88.6%), and an overall negative predictive value (NPV) of 92.9% (95% CI: 85.3%–97.4%). The area under the receiver operating characteristic curve for FFR-CT was significantly superior to standard anatomical CTCA luminal assessment alone (0.88 vs. 0.65, p < 0.001). Fractional flow reserve computed non-invasively from CTCA datasets maintains high diagnostic precision and high negative predictive value even in severely calcified coronary arteries, reducing unnecessary diagnostic invasive procedures.

Keywords: Computed tomography coronary angiography, Fractional flow reserve, Coronary calcification, Computational fluid dynamics, Myocardial ischemia, Diagnostic accuracy

Received: July 12, 2019; Revised: August 25, 2019; Accepted: September 10, 2019; Published: October 22, 2019