Cardiac pauses in competitive athletes: a systematic review examining the basis of current practice recommendations.

AIMS: It is generally recommended that individuals aspiring to competitive sports should undergo pre-participation cardiovascular assessment, particularly including arrhythmia risk evaluation. In regard to bradyarrhythmias, the 36th Bethesda Conference suggested that asymptomatic cardiac pauses ≤3 s are 'probably of no significance', whereas longer 'symptomatic' pauses may be abnormal. This study focused on assessing the evidence for the '3 s' threshold. METHODS: A systematic literature search was undertaken including Embase (1980-) and Ovid Medline (1950-). The following MeSH terms were used in the database searches: Cardiac.mp & pause.mp. Additionally, pertinent publications found by review of citation lists of identified publications were examined. Individuals with reversible causes of bradyarrhythmia (e.g. drugs) were excluded. RESULTS: The study population comprised 194 individuals with cardiac pauses of 1.35-30 s. In 120 athletes, specific records for pause durations were provided, but it was not always clear whether pauses occurred at rest. Among these 120 athletes, 106 had pauses ≤3 s, of whom 92 were asymptomatic and 14 were symptomatic. Fourteen athletes had pauses >3 s, of whom nine were asymptomatic and five were symptomatic. There were no deaths during follow-up (7.46 ± 5.1 years). With respect to symptoms, the ≤3 s threshold had a low-positive predictive value (35.7%) and low sensitivity (26.3%), but good negative predictive value (86.7%) and specificity (91%). CONCLUSION: While the evidence is not incontrovertible, the 3 s pause threshold does not adequately discriminate between potentially asymptomatic and symptomatic competitive athletes, and alone should not be used to exclude potential competitors.

Blunted Chronotropic Response to Hypotension in Cough Syncope.

OBJECTIVES: This study compared hemodynamic and chronotropic responses to cough in cough syncope (CS) patients to those in control subjects. BACKGROUND: Cough syncope is an uncommon form of situational fainting variously attributed to both reflex and mechanical causes. We hypothesized that if baroreflex responses contribute to CS, post-cough hypotension should be associated with cardioinhibition comparable to that observed in other reflex faints. METHODS: The study population consisted of 8 CS patients (group 1), 21 patients with vasovagal syncope (group 2), and 6 patients with nonvertiginous "lightheadedness" (group 3). Testing with patients seated included volitional coughing that achieved a transient blood pressure (BP) of ≥200 mm Hg. Beat-to-beat blood pressure (systolic blood pressure [SBP]) before cough, minimum cough-induced SBP and heart rate (HR) (beats/min) after cough, and HR change during cough-induced hypotension were recorded, along with SBP recovery time from SBP nadir after cough. RESULTS: Compared to controls, cough-induced SBP drop was greater in CS patients (CS patients: -48 ± 13.1 mm Hg vs. -29 ± 11.2 mm Hg for group 2 controls; p = 0.005; or -25 ± 10 mm Hg in group 3 controls; p = 0.02), and recovery time was longer (CS: 46 ± 19 s vs. 11 ± 3.6 s in group 1 controls; p = 0.002; or 12 ± 5 s in group 3 controls; p = 0.01). Furthermore, despite greater induced hypotension, post-cough chronotropic response was less in CS patients (+15% above baseline rate) than in either group 2 (+31% above baseline rate; p < 0.001) or group 3 (+28%; p = 0.01) controls. CONCLUSIONS: In CS patients, post-cough chronotropic response is blunted compared to that in controls despite greater cough-induced hypotension favoring baroreflex cardioinhibition contribution to the pathophysiology of cough syncope.

Risk Stratification of Patients Presenting with Transient Loss of Consciousness.

Important goals in the initial evaluation of patients with transient loss of consciousness include determining whether the episode was syncope and choosing the venue for subsequent care. Patients who have high short-term risk of adverse outcomes need prompt hospitalization for diagnosis and/or treatment, whereas others may be safely referred for outpatient evaluation. This article summarizes the most important available risk assessment studies and points out key differences among the existing recommendations. Current risk stratification methods cannot replace critical assessment by an experienced physician, but they do provide much needed guidance and offer direction for future risk stratification consensus development.

Syncope: classification and risk stratification.

BACKGROUND: Syncope is one of the most common reasons for emergency department and urgent care clinic visits. The management of syncope continues to be a challenging problem for front-line providers inasmuch as there are a multitude of possible causes for syncope ranging from relatively benign conditions to potentially life-threatening ones. In any event, it is important to identify those syncope patients who are at immediate risk of life-threatening events; these individuals require prompt hospitalization and thorough evaluation. Conversely, it is equally important to avoid unnecessary hospitalization of low-risk patients since unneeded hospital care adds to the healthcare cost burden. RESULTS: Historically, front-line providers have taken a conservative approach with admission rates as high as 30-50% among syncope patients. A number of studies evaluating both the short- and long-term risk of adverse events in patients with syncope have focused on development of risk-stratification guidelines to assist providers in making a confident and well-informed choice between hospitalization and out-patient referral. In this regard, a much needed consensus on optimal decision-making process has not been developed to date. However, knowledge from various available risk-stratification studies can be helpful. CONCLUSION: This review summarizes the findings of various risk-stratification studies and points out key differences between them. While, the existing risk-stratification methods cannot replace critical assessment by an experienced physician, they do provide valuable guidance. In addition, the various risk-assessment schemes highlight the need for careful initial clinical assessment of syncope patients, selective testing, and being mindful of the short- and long-term risks.

Atrial fibrillation and heart failure: intersecting populations, morbidities, and mortality.

Heart failure (HF) and atrial fibrillation (AF) are the only two cardiovascular disorders that continue to increase in magnitude in the United States. The purpose of this brief overview is to provide a description of these two cardiovascular epidemics of HF and AF as they interact, and to provide additional information regarding the emerging influence of genetics and environment in the development of AF in the HF setting. These two modern epidemics are highly interactive and highly age-dependent. The development of new AF in a patient with either HF with preserved ejection fraction or HF with reduced ejection fraction possesses challenging management issues for practicing physicians. Control of heart rate is always prudent though still not precisely defined. The need to restore normal sinus rhythm is highly patient-dependent and strategies will vary. Elderly patients derive the most benefit from anticoagulation, but are also more prone to falls and bleeding complications. Today, we know much more about AF and HF and how they interact. The extent of AF/HF challenge is now widely recognized. It is inevitable that as people age, they will develop structural and functional changes in the cardiovascular system, some of which will predispose to the development of HF and AF. Not every case of HF or AF is preventable. Nevertheless, it is only throughout careful observations and further studies that we will be able to better manage these two Goliaths.

Haematological, neurological and electrocardiographic findings in secondary hypothermia.

The association between secondary hypothermia and pancytopaenia is uncommon. A young woman presented with chronic hypothermia (28.8-34.6°C) secondary to surgical hypothalamic injury postcraniopharyingioma resection as a child. Associated findings included pancytopaenia (haemoglobin 8.1 g/dl, leucocytes 3500/mm(3), platelets 63,000/mm(3)), ataxia, upper motor neuron signs, decreased level of consciousness and new ECG changes. An extensive evaluation failed to reveal any cause of pancytopaenia other than chronic hypothermia. The haematological and neurological changes improved after active rewarming.

Vasodepressor cough syncope masked by sleep apnea-induced asystole.

Vasodepressor Cough Syncope. Cough syncope is classified among the neural-reflex "situational" faints, but whether the clinical consequences in affected individuals result from reflex triggered bradyarrhythmia or vasodepressor-induced hypotension, or both, is often unknown. In this report we describe findings in a patient with a clinical history consistent with cough syncope, and in whom documented multiple asystolic spells were at first believed to be responsible for symptoms. However, pacemaker therapy initiated at an outside facility failed to suppress symptoms, and subsequent referral for more detailed autonomic study revealed the asystole to be due to sleep apnea, whereas cough-induced vasodepressor hypotension was the basis of syncope in this individual; the latter provided a pathophysiologic target for prevention of recurring symptoms. (J Cardiovasc Electrophysiol, Vol. 23, pp. 1024-1027, September 2012).