Circulation: Arrhythmia and Electrophysiology February 2020 Issue

Paul J. Wang: Welcome to the monthly podcast On the Beat for Circulation: Arrhythmia and Electrophysiology. I'm Dr Paul Wang, editor in chief, with some of the key highlights from this month's issue.

In our first paper, Ling Kuo and associates examine the association between left atrial high-resolution late gadolinium enhancement on cardiac magnetic resonance and electrogram abnormalities in patients with atrial fibrillation or AF. They found that in 40 AF patients age 63.2 years with a mean of 1312 electrogram points per patient. Lower bipolar voltage was associated with higher signal intensity Z score in patients who had undergone previous ablation coefficient equals -0.049 P < 0.001 but not in ablation-naive patients, coefficient = -0.004, P = 0.7. Left atrial high-resolution late gadolinium enhancement activation delay was associated with signal intensity z-score in patients with previous ablation, signal intensity Z score coefficient = 0.004, P < 0.001 but not in ablation-naive patients. In contrast, increased left atrial high-resolution late gadolinium enhancement fractionation was associated with signal intensity z-score coefficient 0.012, P = 0.03, and left atrial high-resolution late gadolinium enhancement coefficient 0.035, P < 0.001 only in ablation-naive patients.

The authors concluded that the association of left atrial late gadolinium enhancement with voltage is modified by ablation in ablation naive patients. Atrial late gadolinium enhancement is associated with electrogram fractionation even in the absence of voltage abnormality.

In our next paper, Laila Staerk and associates examine the associations between 85 protein biomarkers and incident atrial fibrillation or AF in patients 50 years of age or greater, from the Framingham Heart Study Offspring and Third Generation cohorts. Out of 3378 participants, 54% women, mean age 61.5 years, 401 developed AAF over a mean follow-up of 12.3 years. They observed a lower hazard of incident atrial fibrillation associated with mean higher levels of incident like growth factor hazard ratio per one standard deviation increment in protein level equals 0.84, and higher hazard ratio of incident atrial fibrillation associated with higher mean levels of both insulin-like growth factor-binding protein and N-terminal pro-B-hormone type a natriuretic peptide.

In our next paper, Eoin Donnellan and associates examine changes in atrial fibrillation or AF type following bariatric surgery in 220 morbidly obese patients body mass index ≥40 kilograms per meter square. They observed a reduction in body mass index following bariatric surgery from 49.7 to 37.2 kilograms per meter square. Weight loss was greatest in the gastric bypass group with a mean percentage loss of 25% compared to 19% in patients underwent sleeve gastrectomy, and 16% following gastric banding. P < 0.0001 reversal of AF type occurred in 71% of patients following gastric bypass, 56% of patients who underwent sleeve gastrectomy and 50% of patients following gastric banding, P = 0.004. They found that on Cox proportional hazards analysis percent weight loss was significantly associated with AFib reversal, P = 0.0002.

In our next paper, Thomas Pezawas and associates examine the role of diastolic function assessment to predict arrhythmic death.

They prospectively enrolled 120 patients with ischemic, 60 patients with dilated cardiomyopathy, and 30 patients with normal left ventricular ejection fraction. After an average of 7.0 years, arrhythmic death or resuscitated cardiac arrest was observed in 28 (or 13.3%) and 33 (or 15.7%) of patients respectively. Non-arrhythmic death was found in 41 (or 19.5%) of patients. On Kaplan Meier analysis patients with dysfunction grade III had the highest risk of arrhythmic death or resuscitated cardiac arrest, P < 0.001.

This finding was independent from the degree of left ventricular ejection fraction and was observed in patients with ejection fraction ≤ 35%, P = 0.001 and with a left ejection fraction > 35%, P = 0.014. Non-arrhythmic mortality was highest and patients with dysfunction grade III. This was true for patients with left ventricular ejection fraction ≤to 35%, or > 35%. In an adjusted model for relevant confounding factors, grade III dysfunction was associated with a 3.5-fold, increased risk of arrhythmic death or resuscitated cardiac arrest in the overall study population hazard ratio of 3.52, P < 0.001.

In our next paper, because asthma and atrial fibrillation share an underlying inflammatory pathophysiology, Matthew Tattersall and associates hypothesize that persistent asthmatics would be at higher risk for developing atrial fibrillation or AF and this association would it be attenuated by adjust for baseline markers of systemic inflammation.

The authors examined 6,615 patients mean age 62.0 years, 47% male, 27% African American, 12% Chinese, 22% Hispanic. In the MESA, or multiethnic study of atherosclerosis study, a prospective longitudinal study of adults free of cardiovascular disease at baseline, AF incident rates were 0.11 events per ten person-years for non-asthmatics, 0.11 events per ten person-years for intermittent asthmatic, and 0.19 events per ten person-years for persistent asthmatic. Log rank P value = 0.008. In risk factor adjusted models, persistent asthmatic had a greater risk of incident atrial fibrillation has a ratio of 1.49 P = 0.03. Interleukin six tumor necrosis factor and D-dimer predicted incident atrial fibrillation, but the relationship between asthma and incident AFib was not attenuated by adjustment for any inflammation marker.

In our next paper, Deepak Pasupula and associates examine the survival trends in out-of-hospital cardiac arrest patients before and after the introduction of the 2010 AHA CPR guidelines in the United States. They sought to assess survival trends in out-of-hospital cardiac arrest patients before and after the introduction of the 2010 AHA CPR guidelines.

Using the retrospective observational study from the National Emergency Department sample, they found that the change in the 2010 AHA CPR guidelines was associated with only small improvement in Emergency Department survival and survival-to-discharge trends among US out-of-hospital cardiac arrest patients, and only one out of six out-of-hospital cardiac arrest patients survive to discharge. They studied 1,282,520 patients presenting to the emergency department after out-of-hospital cardiac arrest, meaning age 65.8 years, 62% males. The average survival after emergency department care increased only 1%, 22% before 2010 in 23% after 2010, P < 0.001, and there was no significant change in the discharge rate.

In our next paper, Julian Stewart and associates examine the changes in cardiac output, inappropriate sinus tachycardia, postural tachycardia syndrome, vasovagal syncope in the presence of symptomatic excessive heart rate. They studied 12 healthy controls, nine inappropriate sinus tachycardia, 30 vasovagal syncope and 30 postural tachycardia syndrome patients, selected randomly by disorder. Subjects were instrumented for electrocardiography, beat-to-beat blood pressure, respiratory rate, CO-Model flow algorithm, and central blood volume from impedance cardiography. At baseline heart rates, diastolic and mean arterial pressure in inappropriate sinus and tachycardia postural tachycardia syndrome were higher versus controls. Upright mean heart rate increased most in postural tachycardia syndrome. Then in inappropriate sinus tachycardia, in vasovagal syncope with diverse changes in cardiac output, systemic or vascular resistance, and central blood volume. Each patient grouping was separately and collectively analyzed for heart rate change following transition from in-phase to anti-phase as heart rate increased.

Heart rates transition =115 for inappropriate sinus tachycardia, 123 for postural orthostatic tachycardia syndrome and 124 for vasovagal syncope. P=ns. Controls never reached the transitional heart rate. The authors concluded that excessive heart rate independently and equivalently reduces upright cardiac output in inappropriate sinus tachycardia, vasovagal and postural tachycardia syndrome patients.

In our next paper, Adam Graham, Michele Orini, and associates examined the accuracy of non-invasive ECG imaging or ECGI in localizing the origin of arrhythmias during catheter ablation of ventricular tachycardia and structurally abnormal hearts. In 18 patients, 29 ventricular tachycardias were examined. The distance between the site of origin and sites of earliest activation in ECGI were 22.6 millimeters with a first quartile of 13.9, and third quartile of 36.2 millimeters. ECGI mapped ventricular sites of origin onto the correct AHA segment with a higher accuracy than a validated 12-lead ECG algorithm, 83.3% versus 38.9%, P=0.015.

In a research letter, Shadi Yaghi and associates report about the ability of left atrial appendage morphology to improve prediction of stagnant flow and stroke risk in atrial fibrillation.

In an interesting review article, Charles Swerdlow and associates provide an in depth look at how impedance may provide insights into lead performance.

That's it for this month. We hope that you will find the journal to be the go-to place for everyone interested in the field. See you next time.

This program is copyright American Heart Association 2020.