Pierre Qian

Transcatheter Aortic Valve Implantation (TAVI) in Patients With Bicuspid Aortic Valve Stenosis – Systematic Review and Meta-Analysis

BACKGROUND Transcatheter aortic valve implantation (TAVI) is a feasible interventional technique for severe aortic stenosis in patients who are deemed inoperable or at high surgical risk. There is limited evidence for the safety and efficacy of TAVI in patients with bicuspid aortic valves (BAV), the most common congenital valve abnormality. In many TAVI trials, patients with BAV have been contraindicated due to concerns surrounding abnormal valve geometry, leading to malfunction or malpositioning. A systematic review and meta-analysis was conducted in order to assess the current evidence and relative merits of TAVI in aortic stenosis patients with BAV. METHOD From six electronic databases, seven articles including 149 BAV and 2096 non-BAV patients undergoing TAVI were analysed. RESULTS Between the BAV and no-BAV cohorts, there was no difference in 30-day mortality (8.3% vs 9.0%; P=0.68), post-TAVI mean peak gradients (weighted mean difference, 0.36 mmHg; P=0.55), moderate or severe paravalvular leak (25.7% vs 19.9%; P=0.29), pacemaker implantations (18.5% vs 27.9%; P=0.52), life-threatening bleeding (8.2% vs 13.9%; P=0.33), major bleeding (20% vs 16.8%; P=0.88), conversion to conventional surgery (1.9% vs 1.2%; P=0.18) and vascular complications (8.6% vs 10.1%; P=0.32). CONCLUSIONS Preliminary short and mid-term pooled data from observation studies suggest that TAVI is feasible and safe in older patients with BAV. While future randomised trials are not likely, larger adequately-powered multi-institutional studies are warranted to assess the long-term durability and complications associated with TAVI in older BAV patients with severe aortic stenosis.

Five seconds of 50–60 W radio frequency atrial ablations were transmural and safe: an in vitro mechanistic assessment and force-controlled in vivo validation

Aims Longer procedural time is associated with complications in radiofrequency atrial fibrillation ablation. We sought to reduce ablation time and thereby potentially reduce complications. The aim was to compare the dimensions and complications of 40 W/30 s setting to that of high-power ablations (50-80 W) for 5 s in the in vitro and in vivo models. Methods and results In vitro ablations-40 W/30 s were compared with 40-80 W powers for 5 s. In vivo ablations-40 W/30 s were compared with 50-80 W powers for 5 s. All in vivo ablations were performed with 10 g contact force and 30 mL/min irrigation rate. Steam pops and depth of lung lesions identified post-mortem were noted as complications. A total of 72 lesions on the non-trabeculated part of right atrium were performed in 10 Ovine. All in vitro ablations except for the 40 W/5 s setting achieved the critical lesion depth of 2 mm. For in vivo ablations, all lesions were transmural, and the lesion depths for the settings of 40 W/30 s, 50 W/5 s, 60 W/5 s, 70 W/5 s, and 80 W/5 s were 2.2 ± 0.5, 2.3 ± 0.5, 2.1 ± 0.4, 2.0 ± 0.3, and 2.3 ± 0.7 mm, respectively. The lesion depths of short-duration ablations were similar to that of the conventional ablation. Steam pops occurred in the ablation settings of 40 W/30 s and 80 W/5 s in 8 and 11% of ablations, respectively. Complications were absent in short-duration ablations of 50 and 60 W. Conclusion High-power, short-duration atrial ablation was as safe and effective as the conventional ablation. Compared with the conventional 40 W/30 s setting, 50 and 60 W ablation for 5 s achieved transmurality and had fewer complications.

Periprocedural effects of statins on the incidence of contrast-induced acute kidney injury: A systematic review and trial sequential analysis

BACKGROUND Contrast-induced acute kidney injury (CI-AKI) is a potential complication in coronary angiography (CAG) and percutaneous coronary interventions (PCI). Prior randomized controlled trials (RCTs) have suggested that statins may play a role in reducing rates of CI-AKI, however it is not clear how firm the current evidence is. OBJECTIVES The aim of this study was to conduct a meta-analysis and trial sequential analysis to determine the effects of statins in lowering CI-AKI rates in CAG and PCI. METHODS A systematic literature search was performed to include all RCTs comparing statins (treatment arm) versus low-dose statins or placebo (control arm) as pretreatment for CAG and/or PCI. A traditional meta-analysis and several subgroup analyses were conducted using traditional meta-analysis with relative risk (RR), trial sequential analysis, and meta-regression analysis. RESULTS 14 RCTs met our inclusion criteria giving a total of 2992 statin treated (49.6%) and 3041 control patients (50.4%). There was a significant reduction in CI-AKI in the statin group compared to controls (3.7% vs 8.3%, RR, 0.46; p=<0.00001). Trial sequential analysis using a relative risk reduction threshold of 20%, power 80% and type 1 error of 5%, indicated that the evidence is firm. A greater risk reduction in CI-AKI in the statin group significantly correlated with higher estimated glomerular filtration rate (eGFR; p=0.003) CONCLUSIONS: The present trial sequential analysis provides support for statins in reducing the incidence of CI-AKI in patients undergoing CAG/PCI. This effect appeared to be greater in patients with higher eGFR.

Clinical significance of early atrial arrhythmia type and timing after single ring isolation of the pulmonary veins

AIMS Early atrial arrhythmia following atrial fibrillation (AF) ablation is associated with higher recurrence rates. Few studies explore the impact of early AF (EAF) and atrial tachycardia (EAT) on long-term outcomes. Furthermore, EAF/EAT have not been characterized after wide pulmonary vein isolation. We aimed to characterize EAF and EAT and its impact on late AF (LAF) and AT (LAT) after single ring isolation (SRI). METHODS AND RESULTS We recruited 119 (females 21, age 58 ± 10 years) consecutive patients with AF (paroxysmal 76, persistent 43) undergoing SRI. Early atrial fibrillation/ early atrial tachycardia was defined as AF/AT within 3 months post-procedure (blanking period). Patients were followed for median 2.8[2.2-4] years. Early atrial fibrillation occurred in 28% (n = 33) and EAT in 25% (n = 30). At follow-up, 25% (n = 30) had LAF and 28% (n = 33) had LAT. Patients with EAF and EAT had higher rates of LAF (48 vs. 16%, P<0.0001) and LAT (60 vs. 16%, P < 0.0001), respectively. Independent predictors of LAF were EAF (3.53(1.72-7.29) P = 0.001); and of LAT were EAT (5.62(2.88-10.95) P < 0.0001) and procedure time (1.38/ h(1.07-1.78) P = 0.04). Importantly, EAF did not predict LAT and EAT did not predict LAF. Early atrial fibrillation late in the blanking period was associated with higher rates of LAF (73% for month 3 vs. 25% for Months 1-2, P = 0.004). However, EAT timing did not predict LAT. CONCLUSION Early atrial fibrillation and EAT are predictive of LAF and LAT, respectively. Early atrial fibrillation late in the blanking period has greater predictive significance for LAF. This timing is not relevant for LAT. Early arrhythmia type and timing have important prognostic significance following SRI. CLINICAL TRIAL REGISTRATION http://www.anzctr.org.au;ACTRN12606000467538.

The effect of N-acetylcysteine on the incidence of contrast-induced kidney injury: A systematic review and trial sequential analysis

BACKGROUND There have been a myriad of studies investigating the effectiveness of N-acetylcysteine (NAC) in the prevention of contrast induced nephropathy (CIN) in patients undergoing coronary angiography (CAG) with or without percutaneous coronary intervention (PCI). However the consensus is still out about the effectiveness of NAC pre-treatment due to vastly mixed results amongst the literature. OBJECTIVES The aim of this study was to conduct a meta-analysis and trial sequential analysis to determine the effects of pre-operative NAC in lowering the incidence of CIN in patients undergoing CAG and/or PCI. METHODS A systematic literature search was performed to include all randomized controlled trials (RCTs) comparing NAC versus control as pretreatment for CAG and/or PCI. A traditional meta-analysis and several subgroup analyses were conducted using traditional meta-analysis with relative risk (RR), trial sequential analysis, and meta-regression analysis. RESULTS 43 RCTs met our inclusion criteria giving a total of 3277 patients in both control and treatment arms. There was a significant reduction in the risk of CIN in the NAC treated group compared to control (OR 0.666; 95% CI, 0.532-0.834; I2=40.11%; p=0.004). Trial sequential analysis, using a relative risk reduction threshold of 15%, indicates that the evidence is firm. CONCLUSIONS The results of the present paper support the use of NAC in the prevention of CIN in patients undergoing CAG±PCI. Future studies should focus on the benefits of NAC amongst subgroups of high-risk patients.

A Novel Microwave Catheter Can Perform Noncontact Circumferential Endocardial Ablation in a Model of Pulmonary Vein Isolation.

Pulmonary vein isolation is an effective treatment for atrial fibrillation. Current endocardial ablation techniques require catheter contact for lesion formation. Inadequate or inconsistent catheter contact results in difficulty with achieving acute and long‐term isolation and consequent atrial arrhythmia recurrence. Microwave energy produces radiant heating and therefore can be used for noncontact catheter ablation. We hypothesized that it is possible to design a microwave catheter to produce a circumferential transmural thermal lesion in an in vitro model of a pulmonary vein antrum.

Influence of Intramyocardial Adipose Tissue on the Accuracy of Endocardial Contact Mapping of the Chronic Myocardial Infarction Substrate

Background: Recent studies have demonstrated that intramyocardial adipose tissue (IMAT) may contribute to ventricular electrophysiological remodeling in patients with chronic myocardial infarction. Using an ovine model of myocardial infarction, we aimed to determine the influence of IMAT on scar tissue identification during endocardial contact mapping and optimal voltage-based mapping criteria for defining IMAT dense regions. Method and Results: In 7 sheep, left ventricular endocardial and transmural mapping was performed 84 weeks (15–111 weeks) post-myocardial infarction. Spearman rank correlation coefficient was used to assess the relationship between endocardial contact electrogram amplitude and histological composition of myocardium. Receiver operator characteristic curves were used to derive optimal electrogram thresholds for IMAT delineation during endocardial mapping and to describe the use of endocardial mapping for delineation of IMAT dense regions within scar. Endocardial electrogram amplitude correlated significantly with IMAT (unipolar r=−0.48±0.12, P<0.001; bipolar r=−0.45±0.22, P=0.04) but not collagen (unipolar r=−0.36±0.24, P=0.13; bipolar r=−0.43±0.31, P=0.16). IMAT dense regions of myocardium reliably identified using endocardial mapping with thresholds of <3.7 and <0.6 mV, respectively, for unipolar, bipolar, and combined modalities (single modality area under the curve=0.80, P<0.001; combined modality area under the curve=0.84, P<0.001). Unipolar mapping using optimal thresholding remained significantly reliable (area under the curve=0.76, P<0.001) during mapping of IMAT, confined to putative scar border zones (bipolar amplitude, 0.5–1.5 mV). Conclusions: These novel findings enhance our understanding of the confounding influence of IMAT on endocardial scar mapping. Combined bipolar and unipolar voltage mapping using optimal thresholds may be useful for delineating IMAT dense regions of myocardium, in postinfarct cardiomyopathy.

Influence of BMI on inducible ventricular tachycardia and mortality in patients with myocardial infarction and left ventricular dysfunction: The obesity paradox

BACKGROUND There is little known about the influence of obesity on ventricular electrical remodelling after myocardial infarction. The aim of our study was to assess the relationship between body mass index (BMI) and the primary outcome of inducible-VT and the secondary outcome of all-cause mortality in consecutive patients who presented with ST elevation myocardial infarction (STEMI) and LV-dysfunction (LVEF ≤ 40%). METHODS AND RESULTS Consecutive patients (n = 380) with STEMI and LV-dysfunction (LVEF ≤ 40%) underwent electrophysiological (EP) studies for risk-stratification. Inducible-VT ≥200 ms cycle-length (CL) with one to four extra-stimuli (ES) was considered abnormal. Patients were classified according their body mass index (BMI) to be normal (18.5-24.9), overweight (25-29.9) or obese (>30). The primary outcome of inducible-VT occurred in 42.7%, 21.5% and 21% of normal weight, overweight and obese patients respectively (p < 0.001). When adjusting for ejection-fraction, hypertension and triple-vessel-disease, normal BMI remained a significant predictor for inducible-VT. All-cause mortality was higher in patients with normal weight (12.8%) when compared to overweight (3.2%) and obese (3.8%) patients (p = 0.002) and was mainly driven by increased cardiac-death (6.8%, 1.9% and 1.9% in normal, overweight and obese patients respectively, p = 0.05). After adjusting for age, EF, and hypertension, normal BMI remained a significant predictor of mortality. CONCLUSION In patients presenting with STEMI and LV-dysfunction, BMI appears to be a significant predictor of inducible-VT and all-cause mortality, with worse outcomes for those with normal weight, when compared to overweight or obese individuals. These findings are consistent with the obesity-paradox.

Transcatheter non-contact microwave ablation may enable circumferential renal artery denervation while sparing the vessel intima and media.

AIMS Trials of transcatheter renal artery denervation (RDN) have failed to show consistent antihypertensive efficacy. Procedural factors and limitations of radiofrequency ablation can lead to incomplete denervation. The aim of the study was to show that non-contact microwave catheter ablation could produce deep circumferential perivascular heating while avoiding injury to the renal artery intima and media. METHODS AND RESULTS A novel microwave catheter was designed and tested in a renal artery model consisting of layers of phantom materials embedded with a thermochromic liquid crystal sheet, colour range 50-78°C. Ablations were performed at 140 W for 180 sec and 120 W for 210 sec, delivering 25,200 J with renal arterial flow at 0.5 L/min and 0.1 L/min. Transcatheter microwave ablations 100-160 W for 180 sec were then performed in the renal arteries of five sheep. In vitro, ablations at 140 W and 0.5 L/min flow produced circumferential lesions 5.9±0.2 mm deep and 19.2±1.5 mm long with subendothelial sparing depth of 1.0±0.1 mm. In vivo, transcatheter microwave ablation was feasible with no collateral visceral thermal injury. There was histological evidence of preferential outer media and adventitial ablation. CONCLUSIONS Transcatheter microwave ablation for RDN appears feasible and provides a heating pattern that may enable more complete denervation while sparing the renal arterial intima and media.

Circuit Impedance Could Be a Crucial Factor Influencing Radiofrequency Ablation Efficacy and Safety: A Myocardial Phantom Study of the Problem and Its Correction

Circuit impedance could affect the safety and efficacy of radiofrequency (RF) ablation.