JACC in a Flash

Featured topics and Editors’ Picks from all of ACC's JACC Journals.

Special Issue of JACC Examines Public Health Impact of CVD, Prevention

Cardiology Magazine, Jan. 2017

A special issue of the Journal of the American College of Cardiology (JACC), published May 28, focuses on the promotion of cardiovascular health, including issues that broadly impact public health and the prevention of cardiovascular disease and related conditions.

In a state-of-the-art review, David J.A. Jenkins, MD, PhD, DSC, et al., conclude the current data on use of supplemental vitamins and minerals reinforce advice to focus on healthy dietary patterns, with an increased proportion of plant foods in which many required vitamins and minerals can be found. In another review article, Travis P. Baggett, MD, MPH, et al., explain that cardiovascular disease is a major cause of death among homeless adults, at rates that exceed those in non-homeless individuals. “We suggest practical, patient-centered strategies for delivering preventive and therapeutic cardiovascular care to this vulnerable population,” write the authors. Read More >>>

Other highlights from the annual special issue include a look at the impact of SGLT-2 inhibitors on lowering the risk of death and heart failure in patients with type 2 diabetes without cardiovascular disease; coronary atherosclerotic precursors of acute coronary syndromes that can be found on CTA; capacity to improve short-term cardiovascular disease risk prediction in older adults by adding biomarkers to the Pooled Cohort Equation; data from the YOUNG-MI study showing worse mortality post myocardial infarction in cocaine or marijuana users; and new insights into sex hormones and the ratio of testosterone and estrogen levels post menopause on progression of cardiovascular disease.

Click here to read the full issue of the JACC Cardiovascular Health Promotion issue.

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Do Pulsed Electric Fields Present a New Era of AFib Ablation?

Cardiology Magazine, Jan. 2017

Pulsed electric field ablation is a paradigm-shifting energy source that may have the potential to transform the field of atrial fibrillation (AFib) ablation, according to a study presented at the Heart Rhythm Society’s 39th Annual Scientific Sessions and simultaneously published in JACC: Clinical Electrophysiology.

Vivek Y. Reddy, MD, et al., sought to report the first acute clinical experience of AFib ablation with pulsed electric fields in both catheter-based pulmonary vein isolation and epicardial box lesions during cardiac surgery. Using a custom over-the-wire endocardial catheter for percutaneous transseptal pulmonary vein isolation and a linear catheter for encircling the pulmonary veins and posterior left atrium during concomitant cardiac surgery, pulsed electric field ablation was performed in 22 AFib patients who underwent ablation under general anesthesia. Read More >>>

Of the 22 AFib patients, 15 underwent endocardial pulsed electric field ablation of their pulmonary veins and seven underwent surgical epicardial pulsed electric field ablation of their left atrial posterior wall and pulmonary veins. Endocardial voltage maps were created pre- and post-ablation.

Results showed that catheter pulmonary vein isolation was successful in all 57 pulmonary veins in the 15 patients with a procedure time ranging from 52 to 84 minutes, catheter time 16 to 23 minutes and total pulsed electric field energy delivery time less than 60 seconds per patient. Surgical box lesions were successful in six of the seven patients, with the catheter time for epicardial ablation ranging from 30 to 75 minutes.

Furthermore, the authors found no pulsed electric field catheter-related complications, such as deployment failure, cardiac perforation or catheter entrapment, within the pulmonary veins or valvular apparatus. There was also no evidence of charring or thrombus formation on catheter removal from the left atrium.

The authors explain that the most unique aspect to a pulsed electric field is its tissue selectivity, as tissues have specific characteristic threshold field strengths that induce necrosis. They add that pulsed electric fields may be uniquely suited for AFib ablation because cardiomyocytes have among the lowest threshold values of any tissue, the absence of coagulative necrosis obviates the risk of pulmonary vein stenosis and the speed of pulsed electric fields has advantages for both lab workflow and safety of left-sided procedures. “Unlike thermally-based energy technologies, pulsed electric field ablation was distinguished by its ability to achieve ultra-rapid pulmonary vein isolation or posterior box isolation with total ablation times of less than 60 seconds,” the authors conclude. “[It] is both feasible and safe and associated with excellent acute efficacy.”

Reddy VY, Koruth J, Jais P, et al. JACC Clin Electrophysiol 2018;May 11:[Epub ahead of print].

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Study Finds CCM is Safe, Improves Exercise Tolerance and QOL in HF

Cardiology Magazine, Jan. 2017

In patients with heart failure (HF), cardiac contractility modulation (CCM) may be safe, may improve exercise tolerance and quality of life and may lead to fewer hospitalizations, according to results of the FIX-HF-5 confirmatory study presented at the Heart Rhythm Society’s 39th Annual Scientific Sessions and simultaneously published in JACC: Heart Failure.

William T. Abraham, MD, FACC, et al., conducted a subgroup analysis of the FIX-HF-5 study and looked at 160 patients with NYHA functional class III or IV symptoms, QRS duration <130 ms and ejection fraction between 25-45 percent who were randomized to a control group of continued medical therapy (n=86) or treatment with CCM (n=74, unblinded) for 24 weeks. Read More >>>

Results showed that the difference in peak oxygen consumption between the two groups was 0.84 ml O2/kg/min. In addition, Minnesota Living With Heart Failure questionnaire (p<0.001), NYHA functional class (p<0.001) and 6-min hall walk (p=0.02) were all better in the treatment vs. control group.

The authors note there were seven device-related events, yielding a lower bound of 80 percent of patients free of events, therefore satisfying the primary safety endpoint. The composite of cardiovascular death and HF hospitalizations was reduced from 10.8 percent to 2.9 percent (p=0.048).

The authors conclude that their results “supplement and confirm results of prior studies.” They add that moving forward, “future research can explore the impact of CCM in patients with prolonged QRS duration in addition to CRT, in particular in CRT nonresponders.”

Abraham WT, Kuck KH, Goldsmith RL, et al. JACC Heart Fail 2018;May 10:[Epub ahead of print].

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Different Power, Duration Yield Different Ablation Lesion Characteristics

Cardiology Magazine, Jan. 2017

Varying power and duration during radiofrequency ablation (RFA) may confer different ablation lesion characteristics that can be tailored based on the substrate or anatomy that is being ablated, according to a study presented at the Heart Rhythm Society’s 39th Annual Scientific Sessions and simultaneously published in JACC: Clinical Electrophysiology.

Ryan T. Borne, MD, FACC, et al., assembled an ex vivo model consisting of viable bovine myocardium, a submersible load cell, circulating bath and an open irrigated ablation catheter. RFA was delivered at powers of 20, 30, 40 and 50 W and at various time intervals (15, 30, 60 and 90 s) for each power. Ablation lesion characteristics and volumes were analyzed. In addition, for ex vivo tissue temperature analyses, RFA was delivered at 50 W for 5 s and 20 W for 30 s with 10 g of force while tissue temperatures at various depths and lesion volumes were measured. An in vivo porcine thigh preparation model was used to perform RFA at 50 W for 5 s and 20 W for 30 s. Lesion volumes were analyzed. Read More >>>

In the ex vivo model, greater power delivery and longer radiofrequency time increased ablation lesion size. Compared with a proportional change in radiofrequency duration, the same proportional increases in power produced a significantly larger lesion volume. Higher powers for shorter duration created larger ablation lesions than lower powers for longer duration. If force was constant, lesion size would increase proportionally to power and only half as much for duration of ablation. Peak tissue temperatures were not statistically different for 50 W/5 s and 20 W/30 s at 2 mm and 4 mm depths. However, for 50 W/5 s, the slope of temperature rise was greater at 2 mm and 4 mm compared with 20 W/30 s.

In the in vivo model, neither lesion volume nor diameter was statistically different for 50 W/5 s and 20 W/30 s, although there was a trend toward smaller lesion volumes and larger lesion diameters for the high-power/short-duration group.

According to the authors, these findings have important implications during ablation procedures such as pulmonary vein isolation, or for refractory myocardial tissues such as those responsible for certain ventricular arrhythmias.

“Although the ex vivo and in vivo models provide insight into ablation lesion characteristics associated with differences in power and duration of ablation, this insight does not necessarily equate to how best to perform ablation in clinical practice,” the authors write. “Randomized trials should be performed with the specific outcomes being patient-centered clinical endpoints, in which the risks and benefits in differences of ablation strategies can be determined.”

Borne RT, Sauer WH, Zipse MM, et al. JACC Clin Electrophysiol 2018;May 10:[Epub ahead of print].

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Clinical Topics: Acute Coronary Syndromes, Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, ACS and Cardiac Biomarkers, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure, Heart Failure and Cardiac Biomarkers

Keywords: ACC Publications, Cardiology Magazine, Acute Coronary Syndrome, Anesthesia, General, Atrial Fibrillation, Biological Markers, Cannabis, Catheter Ablation, Cause of Death, Cocaine, Cohort Studies, Control Groups, Diabetes Mellitus, Type 2, Electrophysiology, Endocardium, Estrogens, Exercise Tolerance, Heart Atria, Heart Failure, Hospitalization, Myocardial Infarction, Myocardium, Myocytes, Cardiac, Oxygen Consumption, Postmenopause, Pulmonary Veins, Quality of Life, Risk Assessment, Stroke Volume, Testosterone, Thrombosis, Vitamins, Vulnerable Populations, Workflow

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