By Chris Cole
New research was presented at AHA 2018, the annual American Heart Association Scientific Sessions, from November 10-12 in Chicago. The features below highlight some of the studies that emerged from the conference.
Energy Drinks & Endothelial Function
Previous studies have shown adverse effects of energy drinks on blood pressure, pulse rate, and endothelial function. To determine if these findings hold true in younger and healthier population than included in most prior research, study investigators compared baseline endothelial function, blood pressure, and pulse measurements among healthy, nonsmoking medical students (average age, 24.7 years, average BMI, 23.4) with measurements taken 90 minutes after consuming a 24-oz energy drink. Blood pressure increased by 12-14 mmHg and pulse by 12 beats per minute after just 5 minutes; while these values returned to normal by 90 minutes, endothelial function remained substantially reduced. Energy drink consumption resulted in a significantly attenuated peak flow-mediated dilation response, from 5.1% to 2.8%.
Hypothyroidism Overtreatment Linked to AF
Recently published research indicates that elevated free levothyroxine (T4) levels, but not thyroid stimulating hormone, still within the normal reference range are associated with increased risk of atrial fibrillation (AF) incidence and prevalence. To determine if these findings could be replicated in another large population, researchers evaluated data on nearly 175,000 patients with records on free T4 levels who were not on thyroid replacement therapy at study entry. Upon stratifying patients with normal T4 levels into four groups, from low-normal to high-normal, the study team found (after adjustment) that the relative risk of prevalent AF was 40% higher for those in the highest quartile when compared with those in the lowest, translating into a 16% increase in newly developing AF during an average of 6.3 years follow-up. The researchers suggest that “the optimal healthy range of free T4 should be reconsidered and redefined, particularly given the inclination to push T4 levels into higher normal ranges when treating hypothyroidism.”
Post-MI, Yoga-Based Cardiac Rehab
Cardiac rehabilitation has been shown to be highly effective for secondary prevention of acute MI but is underutilized or unavailable to many patients due to high costs, skills required for a large multidisciplinary team, and other factors. A low-cost, scalable cardiac rehab program based on the practice of yoga (Yoga-CaRe) may be an effective and cost-effective approach to increasing cardiac rehab participation. For a study, patients were randomized within 2 weeks of acute MI to 14 weeks of Yoga-CaRe—lifestyle education, three health-rejuvenating exercises, and training in breathing/mediation techniques and 15 yoga postures delivered over 13 weeks by trained yoga instructors, with self-practice at home for the final week—or enhanced standard care (three educational sessions). At 42 months, 6.7% of the Yoga-CaRe group and 7.3% of controls experienced the composite primary endpoint of death, nonfatal MI, nonfatal stroke, and emergency cardiovascular hospitalization. However, in a per-protocol analysis of 1059 patients who completed at least 10 Yoga-CaRe sessions, the number of primary endpoint events was nearly halved. Also, self-rated quality of life, measured by the mean change in the EQ-5D Visual Analog Scale score at 3 months, significantly favored the Yoga-CaRe group over controls.
Vitamin D & Omega-3 for CV Prevention
While previous studies have shown that vitamin D and omega-3 supplementation appear have no significant benefit for the prevention of cardiovascular (CV) disease, these associations are not well understood in a diverse population. For a study, researchers compared the incidence of major CV events (a composite of stroke, MI, and CV-related death) among healthy participants who received vitamin D3 at 2000 IU per day, 1g of marine n-3 fatty acids (omega-3) per day, or placebo. Over 5 years of follow-up, incidence rates of major CV events were not significantly lower in either supplement group when compared with the placebo group. However, when compared with the placebo group, those taking omega-3 had a 28% reduction in MI risk, a risk that was 77% lower among African-American participants.
Environmental Noise & Cardiovascular Risk
Few studies have thoroughly assessed to association between noise exposure and major cardiovascular events. To do just that, researchers assessed data on participants who were free of cardiovascular disease and cancer at baseline. A subset also underwent validated PET/CT imaging to assess arterial inflammation and amygdalar activity. To gauge noise exposure, the researchers used the home addresses of the participants and derived noise-level estimates from the Department of Transportation’s Aviation and Highway Noise Map. Medical records were analyzed over a median follow-up of 3.7 years for the occurrence of cardiovascular events. Those living in areas in the highest quartile of noise exposure had an amygdala/background brain FDG uptake ratio of 0.85, compared with 0.78 for those in the other three quartiles. Participants in the highest quartile for noise exposure also had more than a threefold higher risk for adverse cardiovascular events, which remained significant after adjustment for other cardiovascular risk factors and air pollution.
Daily Smart-Scale Increases Weight Loss
Although self-weighing may promote attainment and maintenance of healthy weight that is important for cardiovascular health, the natural temporal patterns of self-weighing remain unclear. To examine distinct temporal patterns of self-weighing and associated factors and differences in weight changes by self-weighing patterns over time, researchers analyzed remotely transmitted self-weighing data from Health eHeart, an ongoing prospective e-cohort study. Each participant had a 12-month observation, starting from the first day they used a Wi-Fi- or Bluetooth-enabled scale. Researchers did not provide guidance on specific use of the scale or on weight management. Six temporal patterns of self-weighing were identified: non-users, weekly users, rapid decliners (from ~5 days/week to <1 day/week), increasing users (from ~2 days/week to 3 days/week), slow decliners (from ~5 days/week to 3 days/week), and persistent daily users. Over 12 months, persistent daily users (-1.7kg), increasing users (-0.8kg), rapid decliners (-1.9kg), and slow decliners (-1.8kg) lost significant weight, while non-users (-0.2kg) and weekly users (+0.2kg) had no significant weight loss.