J. Cooke

A Single-centre Report on the Characteristics of Tako-tsubo Syndrome

BACKGROUND Tako-tsubo cardiomyopathy is an increasingly recognised phenomenon characterised by chest pain, ECG abnormalities, cardiac biomarker elevation and transient left ventricular dysfunction without significant coronary artery obstruction. AIMS To report the clinical and echocardiographic characteristics from a large single-centre Australian series of patients with Tako-tsubo syndrome. METHODS We prospectively collected data on 23 consecutive patients presenting between November 2005 and November 2007. Baseline demographics, ECG, echocardiography and coronary angiography were performed on nearly all patients. RESULTS All patients presented with chest pain; 87% were female. Various stressors were noted and cardiac Troponin-T was elevated in 91% of patients. All patients had non-obstructive coronary disease at angiography. 19/23 patients had initial and subsequent echocardiography. Mean ejection fraction was 50% at baseline and 64% at follow-up (p<0.0001). Right ventricular dysfunction was present in eight, dynamic left ventricular outflow tract obstruction in two, diastolic dysfunction in seven and two patients had the mid-cavity variant. CONCLUSIONS This large prospective single-centre Australian series of Tako-tsubo syndrome is in concert with previous published series. Complete recovery of left ventricular function on echocardiographic follow-up was typical. Although its pathogenesis remains unclear, early distinction from acute coronary syndromes is important and the prognosis is reassuringly good.

Orthodox coronary artery bypass surgery: The gold standard in surgical coronary artery disease intervention

Abstract Background: Advances in technology have produced a plethora of means to perform coronary revascularisation either surgically (that is, off pump CABG, Heartport CABG) and/or percutaneously (that is, stenting, rotablation). When comparing the results obtained by these new technologies, too often reference is made to results from the CABG operation of previous eras. Before tried and tested procedures are superseded by new, radical ones, it is essential to establish what the contemporary results of the CABG operation are on an unselected, general patient population. Aim: To examine contemporary results of primary orthodox CABG surgery in an unselected patient population from an Australian teaching hospital. Method: This was a prospective study of all patients having primary CABG surgery from 1 January 1996 to 30 June 1998. Results: 1002 patients had CABG. The mean age was 63.1 years, 33% were aged more than 70 years. Perioperative AMI occurred in 0.2% and CVA in 0.7%. Operative mortality for urgent or elective CABG was 0.4%. At 12 months, freedom from a repeat revascularisation procedure was 97%. Conclusion: Contemporary CABG surgery is associated with a very low morbidity and mortality. This is the gold standard in surgical coronary artery disease intervention and forms the benchmark to which alternative treatment strategies must be compared.

Smart watches for heart rate assessment in atrial arrhythmias

BACKGROUND Despite studies demonstrating the accuracy of smart watches (SW) and wearable heart rate (HR) monitors in sinus rhythm, no data exists regarding their utility in arrhythmias. METHODS 102 hospitalized patients were evaluated at rest using continuous electrocardiogram (ECG) monitoring with concomitant SW-HR (FitBit, FB, Apple Watch, AW) for 30 min. RESULTS Across all devices, 38,616 HR values were recorded. Sinus rhythm cohort demonstrated strong agreement for both devices with a low bias (FB & AW Bias = 1 beat). In atrial arrhythmias, AW demonstrated a stronger correlation than FB (AW rs = 0.83, FB rs = 0.56, both p < 0.01) with a lower bias (Bias AW = -5 beats, FB = -18 beats). Atrial flutter demonstrated strongest agreement in both devices with a mean bias <1 beat. However, in AF, there was significant HR underestimation (Bias FB = -28 beats, AW-8 beats) with wide limits of agreement. Despite HR underestimation in AF, when SW recorded HR ≥ 100 in arrhythmias, 98% of values were within ±10-beats of ECG-HR. CONCLUSIONS SW demonstrate strong agreement for HR estimation in sinus rhythm and atrial flutter but underestimates HR in AF. Tachycardic episodes recorded at rest on a SW may be suggestive of an underlying atrial tachyarrhythmia and warrant further clinical evaluation. CLINICAL TRIAL REGISTRATION Australian New Zealand Clinical Trials Registry (www.anzctr.org.au) ACTRN: 12616001374459.

Utility of photoplethysmography for heart rate estimation among inpatients

The accuracy of photoplethysmography (PPG) for heart rate (HR) estimation in cardiac arrhythmia is unknown. PPG‐HR was evaluated in 112 hospitalised inpatients (cardiac arrhythmias (n = 60), sinus rhythm (n = 52)) using a continuous electrocardiogram monitoring as a reference standard. Strong agreement was observed in sinus rhythm HR < 100 and atrial flutter (bias 1 beat), modest agreement in sinus tachycardia (bias 24 beats) and complete heart block (bias −6 beats) and weak agreement with significant HR underestimation was seen in atrial fibrillation (bias 23 beats). Routine utilisation of PPG for HR estimation may delay early recognition of clinical deterioration in certain arrhythmias and sinus tachycardia.

Stress-Induced Cardiomyopathy and Possible Link to Cerebral Executive Function: A Case Report

To the Editor: A complex and poorly understood relationship exists between cerebral and cardiac function.1 Stress produces a range of physiological responses that are relevant to cardiovascular and cerebrovascular disease. Upon stress perception, the hypothalamic-pituitary-adrenocortical (HPA) and sympatho-adrenomedullary axes are activated, increasing bioavailability of cortisol, epinephrine, and norepinephrine.2 Given the reliance of both cardiac and cerebral function on the integrity of this system, any impairment in the form of overstimulation or understimulation may manifest as cardiac and cerebrovascular pathology as illustrated in the case report below. Case report. Ms A, a 56-year-old woman with known hypertension and hypercholesterolemia, was admitted with chest pain following an argument with a family member. She had no history of ischemic heart or neurologic disease. On presentation, she was noted to be confused. Physical examination was unremarkable with no focal neurologic or cardiac abnormality identified. Further investigations revealed troponin T and creatine kinase peak concentrations of 1.15 μg/L (reference range, < 0.03 μg/L) and 614 U/L (reference range, < 180 U/L), respectively. Admission electrocardiogram (ECG) demonstrated sinus rhythm without ischemic changes (Figure 1). Computed tomography scan of the brain was unremarkable. She continued to experience amnesia over the first 12 hours after her admission; amnesia had resolved by the following day. An urgent neurology consultation was sought, and the diagnosis of transient global amnesia was made on the basis of the patient’s clinical features. Figure 1. A 12-Lead Electrocardiogram (A) At Admission, Showing Normal Sinus Rhythm, and (B) 15 Hours Later, Demonstrating Deep T-Wave Inversion Over Leads V2–V5 (anterolateral leads) Resembling Acute Coronary Ischemia Ms A was admitted to the coronary care unit; serial ECG monitoring showed biphasic and deep T-wave inversion over the anterolateral leads (see Figure 1). She underwent coronary angiography, which showed “smooth” coronary arteries and apical “ballooning” on left ventriculography consistent with takotsubo cardiomyopathy. Magnetic resonance imaging of the brain identified an incidental 6-mm left middle cerebral artery aneurysm with no associated hemorrhage or ischemia. Her final diagnoses were stress-induced (takotsubo) cardiomyopathy and transient global amnesia. Adrenergic receptors are abundant throughout the brain,3 myocardium,4 and coronary arteries.5 It is well established that catecholamine signaling through β-adrenergic receptors mediates endogenous regulation of complex central nervous system processes such as attention, arousal, learning, and memory3,6–8 as well as important cardiac functions such as chronotropy, inotropy, and lusitropy. There is general consensus that this “cerebro-cardiac” process occurs via the β-adrenoceptor–mediated cyclic-AMP (cAMP)–dependent protein kinase pathway.9–11 A growing body of evidence suggests that cortisone and epinephrine may also impair memory retrieval and therefore contribute to the mechanism of peritraumatic amnesia. de Quervain and colleagues reported that stress and infusion of cortisone impair memory retrieval in rats12 and humans.13 Sadowski et al10 demonstrated that infusion of epinephrine resulted in impairment of place and response learning. Furthermore, detrimental effects of cortisone on hippocampal function during memory retrieval have been shown to require concurrent norepinephrine-dependent activation of the basolateral part of the amygdala,14,15 which may be via an inhibitory G protein–coupled suppression of cAMP signaling.16,17 Altogether, memory formation, consolidation, and retrieval seem to be a function of β1-adrenergic receptor function, and stress impairs memory retrieval by exerting its action on the β2-adrenergic receptor. Catecholamine overstimulation has been suggested as the key pathogenetic factor in takotsubo cardiomyopathy. This cardiac syndrome is now increasingly recognized by the mental health practitioner as either a disease association18,19 or a complication of a psychiatric treatment, such as electroconvulsive therapy.20,21 Although the exact pathogenesis has not been fully elucidated, data from animal,22 imaging,23 and myocardial histologic24 studies indicate that overactive β-adrenergic signaling, in the presence of supraphysiological catecholamine concentrations, plays a significant role in mediating this phenomenon. Given the density of β-adrenergic receptors are greatest25 in the apical segments of the myocardium, Lyon and colleagues4 suggest these receptors are important in this disease phenomenon, which explains the apical propensity of transient myocardial stunning seen in takotsubo cardiomyopathy. Our case report provides a collection of cardiac and cerebral clinical findings that would support the common mechanistic link described in our review. Further understanding of this complex, dynamic relationship is required to formulate a more targeted preventive and therapeutic management strategy.