Principals and clinical applications of magnetic resonance cardiac spectroscopy in heart failure.

Cardiac magnetic resonance spectroscopy (MRS) is a noninvasive method to assess by-products of myocardial metabolism. Recent developments in shorter scan protocols and more powerful field strengths have created interest in utilizing this technology in studying and characterizing the metabolic derangements in heart failure patients. Our lack of understanding in heart failure could be greatly enhanced by identifying the metabolic changes and eventually modifying metabolic substrate to achieve improved cardiac mechanics with the aid of this technology. However, there are several impediments for the widespread applicability of this technology. This review discusses the principals of human cardiac MRS and literature pertaining to use of MRS in patients with cardiomyopathy.

Dual therapy with oral anticoagulation and single antiplatelet agent versus monotherapy with oral anticoagulation alone in patients with atrial fibrillation and stable ischemic heart disease: a systematic review and meta-analysis.

BACKGROUND: In patients with atrial fibrillation (AF) and stable ischemic heart disease, recent guidelines recommend oral anticoagulant (OAC) monotherapy in preference to OAC + single antiplatelet agent (SAPT) dual therapy. However, these data are based on the results of only two randomized controlled trials (RCTs) and a relatively small group of patients. Thus, the safety and efficacy of this approach may be underpowered to detect a significant difference. We hypothesized that OAC monotherapy will have a reduced risk of bleeding, but similar all-cause mortality and ischemic outcomes as compared to dual therapy (OAC + SAPT). METHODS: A systematic search of PubMed/MEDLINE, EMBASE, and Scopus was conducted. Safety outcomes included total bleeding, major bleeding, and others. Efficacy outcomes included all-cause mortality, cardiovascular mortality, myocardial infarction, stroke, and major adverse cardiovascular events (MACE). RCTs and observational studies were pooled separately (study design stratified meta-analysis). Subgroup analyses were performed for vitamin K antagonists and direct oral anticoagulants (DOACs). Pooled risk ratios (RR) with corresponding 95% confidence intervals (CI) were calculated using the Mantel-Haenszel method. RESULTS: Meta-analysis of 2 RCTs comprising a total of 2905 patients showed that dual therapy (OAC + SAPT) vs. OAC monotherapy was associated with a statistically significant increase in major bleeding (RR 1.51; 95% CI [1.10, 2.06]). There was no significant reduction in MACE (RR 1.10; [0.71, 1.72]), stroke (RR 1.29; [0.85, 1.95]), myocardial infarction (RR 0.57; [0.28, 1.16]), cardiovascular mortality (RR 1.22; [0.63, 2.35]), or all-cause mortality (RR 1.18 [0.52, 2.68]). Meta-analysis of 20 observational studies comprising 47,451 patients showed that dual therapy (OAC + SAPT) vs. OAC monotherapy was associated with a statistically significant higher total bleeding (RR 1.50; [1.20, 1.88]), major bleeding (RR = 1.49; [1.38, 1.61]), gastrointestinal bleeding (RR = 1.62; [1.15, 2.28]), and myocardial infarction (RR = 1.15; [1.05, 1.26]), without significantly lower MACE (RR 1.10; [0.97, 1.24]), stroke (RR 0.93; [0.73, 1.19]), cardiovascular mortality (RR 1.11; [0.95, 1.29]), or all-cause mortality (RR 0.93; [0.78, 1.11]). Subgroup analysis showed similar results for both vitamin K antagonists and DOACs, except a statistically significant higher intracranial bleeding with vitamin K antagonist + SAPT vs. vitamin K antagonist monotherapy (RR 1.89; [1.36-2.63]). CONCLUSIONS: In patients with AF and stable ischemic heart disease, OAC + SAPT as compared to OAC monotherapy is associated with a significant increase in bleeding events without a significant reduction in thrombotic events, cardiovascular mortality, and all-cause mortality.

Updated meta-analysis of closure of patent foramen ovale versus medical therapy after cryptogenic stroke.

BACKGROUND: Among patients with cryptogenic stroke, PFO closure has remained controversial. We hypothesized that with the cumulative number of subjects in randomized controlled trials (RCTs), there is now sufficient power to ascertain whether PFO closure in patients with cryptogenic stroke improves the risk of stroke. METHODS: We performed an updated meta-analysis by including newer RCTs that examined the benefit of PFO closure compared with medical therapy for improvement in risk of stroke. We utilized random effects models to compute the association and performed subgroup analyses by medical therapy, shunt size and presence/absence of atrial septal aneurysm. RESULTS: Overall, 6 RCTS were included with 1839 patients that underwent PFO closure and 1671 patients that received medical therapy and were followed for a period of 2-6 years. The incidence of recurrent stroke was 1.52% among PFO closure group and 3.94% among medical therapy group. There was decreased risk of stroke in PFO closure group (OR 0.34, 95% CI 0.15-0.79, p = 0.012). Patients with larger shunt size derived more benefit from PFO closure than smaller or moderate sized shunts. There was no difference in outcomes by presence or absence of atrial septal aneurysm or type of medical therapy used i.e. antiplatelet therapy only vs. antiplatelet + anticoagulant therapy. CONCLUSION: This meta-analysis of 6 RCTs demonstrated benefits of PFO closure for secondary prevention of stroke among patients with cryptogenic stroke and small increase in risk of new onset atrial fibrillation.

Risk of Mortality Associated With Therapeutic Hypothermia Among Sudden Cardiac Arrest Survivors With Known Heart Failure.

Current guidelines do not inform about use of therapeutic hypothermia among heart failure (HF) patients who suffer from cardiac arrest. We assessed the risk of mortality associated with hypothermia among cardiac arrest survivors with HF. This analysis includes 1,416 comatose patients with cardiac arrest who achieved return of spontaneous circulation on admission and had a left ventricular ejection fraction (LVEF) assessment or HF admission within the previous year. HF was defined as either previous episode of HF or presence of left ventricular ejection fraction <50%. Hazard ratios (HR) and 95% confidence intervals (CI) for association of hypothermia and mortality among patients with and without HF were computed using Cox proportional hazard models adjusted for several risk factors. A propensity score matched analysis was also performed. There were 624 patients (44%) with pre-existing HF and 467 patients (33.0%) received hypothermia. The mortality rate was higher in HF patients treated with hypothermia compared with patients without hypothermia (75.4% vs 53.2%, p <0.0001). Hypothermia was associated with increased mortality among HF patients (HR 1.69; 95% CI 1.27, 2.24, p <0.001) and was not associated with mortality among non-HF patients (HR 1.21; 95% CI 0.93, 1.56, p = 0.15). The association of hypothermia with mortality was higher among HF patients who presented with shockable rhythm compared with nonshockable rhythm (interaction p value = 0.0495). Hypothermia is associated with increased mortality among cardiac arrest survivors with known HF.

Meta-Analysis of Continuous Positive Airway Pressure as a Therapy of Atrial Fibrillation in Obstructive Sleep Apnea.

Atrial fibrillation (AF) is a significant health care problem for patients with obstructive sleep apnea (OSA). Continuous positive airway pressure (CPAP) as a therapy for OSA is underused, and it is unknown if CPAP might reduce rates of AF. We systematically reviewed the published reports on CPAP use and risk of AF. MEDLINE, EMBASE, CINAHL, Web of Science, meeting abstracts, and Cochrane databases were searched from inception to June 2015. Studies needed to report the rates of AF in participants who were and were not on CPAP. Data were extracted by 2 authors. A total of 8 studies on OSA were identified (1 randomized controlled trial) with 698 CPAP users and 549 non-CPAP users. In a random effects model, patients treated with CPAP had a 42% decreased risk of AF (pooled risk ratio, 0.58; 95% confidence interval, 0.47 to 0.70; p <0.001). There was low heterogeneity in the results (I(2) = 30%). In metaregression analysis, benefits of CPAP were stronger for younger, obese, and male patients (p <0.05). An inverse relationship between CPAP therapy and AF recurrence was observed. Results suggest that more patients with AF also should be tested for OSA.