Heartbeat: Highlights from the issue

Antonio Luiz Ribeiro, Catherine M Otto

Patients with acute myocardial infarction(AMI) may benefit from highly specializedservices and interventions, most notablyearly coronary angiography and revascu-larization by percutaneous coronary inter-vention (PCI). These specialized servicesare not universally available among hospi-tals, and inter-hospital transfer is theprimary means for accessing these servicesfor many AMI patients. Although there isevidence that inter-hospital transfer forthe treatment of AMI can reduce cardiacmortality for ST-elevation AMI, the longterm benefit of this strategy is controver-sial, as well as whether this advantageextends to non-ST elevation acute AMIpatients.

In order to address these questions,Ranasinghe and colleagues, (see page 1032)from the The George Institute in Sydney,conducted an investigation to assesswhether hospitalized AMI patients who aretransferred for specialized care during theirAMI event have lower long-term mortality,compared to similar patients solely treatedat the presenting hospital, evaluating theconsistency of findings in transferredpatients with different risk profile andamong various population subgroups. Theauthors used a database of over 40 thou-sand patients with a diagnosis of AMIlinked with the register of deaths of theState of New South Wales and matchedtransferred (25% of total) and non-transferred patients using propensity scorematching, as well as performing several sen-sitivity analyses. They found that trans-ferred patients were about 4 times morelikely to undergo coronary revasculariza-tion and had lower long-term mortality,compared with patients treated solely at thepresenting hospital. This survival advantagewas observed in most subgroups analyzed,including non-ST elevation acute coronarysyndrome patients (figure 1).

In the companion editorial, Prof Galeand colleagues (see page 998), briefly sum-marize the previous literature before point-ing out the potential limitations of thecurrent study and then concluding: “Thereis no doubt that improved, harmonisedsystems of care are needed, which are flex-ible to the patient’s cardiovascular andbleeding risk, estimated reperfusion time,

mode of presentation, availability of spe-cialist services and methods of delivery ofreperfusion. For NSTEMI, until now, theevidence for inter-hospital transfer wasless clear. Ranasinghe and colleagues helpalleviate the uncertainty around inter-hospital transfer for NSTEMI, but the bestcourse of action for the individual patientremains difficult to determine in a real-world situation due to the imbalancebetween transferred and non-transferredpatients”.Overcrowding of emergency depart-

ments (ED) is a worldwide issue that canimpact on the quality of care and patientsatisfaction, with clinical, administrative

and financial implications. Missing casesof acute coronary syndrome that presentswith a non-specific ECG is also a problem,which can lead to a loss of opportunityfor effectively treating diseased patients,and can ultimately lead to a preventabledeath. In this context, Dr Carlton and col-leagues (see page 1041) investigated theability of a novel accelerated diagnosticprotocol (ADP) for suspected acute coron-ary syndrome in successfully identifyinglow-risk patients suitable for discharge atthe emergency department. The proposedADP, which included high-sensitivitytroponin, clinical and ECG data, waseffective in ruling out an acute coronary

Figure 1 Subgroup analysis of long-term mortality between transferred and non-transferredpatients. †P for statistical interaction with IHT, *No interaction term calculated as in-hospital deathdirectly affects long-term mortality. AMI, acute myocardial infarction; IHT, interhospital transfer;STEMI, ST-elevation myocardial infarction; NSTEMI, non-ST-elevation myocardial infarction.

Figure 2 Participant recruitment flow chart. The 132 patients who missed the consent processwere similar in age, gender, risk factors and m-Goldman scores (p>0.05 for all). ADP, accelerateddiagnostic protocol; AMI, acute myocardial infarction; TRUST, Triage Rule-out Usinghigh-Sensitivity Troponin.

Correspondence to Professor Catherine M Otto,Division of Cardiology, University of Seattle, WA 98195,USA; cmotto@u.washington.edu

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syndrome (figure 2) with a sensitivity of98.8% and a negative predictive value of99.7%, and was superior to a stand-alonesingle measurement of high-sensitivitytroponin result in guiding discharge deci-sions. They conclude that this protocolhas the potential to allow early dischargein 40% of patients with suspected ACS,but it has to be tested in a multicenter ran-domized controlled trial before being usedin clinical practice.

In the companion editorial, Prof Halland colleagues (see page 1000) discussthese results and argue that currentlysociety and health care providers mustchoose between “the expectation that allpatients should be correctly and rapidlydiagnosed 100% of the time and neverexperience adverse consequences” versus“the need to balance competing health-care needs, financial and practical consid-erations”, i.e. to do “the greatest good of

the greatest number”, an unsolveddilemma.

This issue of Heart also includes what issure to become a landmark paper by DrDahl and colleagues (see page 1015) aboutlow-flow low-gradient (LFLG) severe aorticstenosis (AS) with normal left ventricularejection fraction (EF). In a retrospectivereview of the Mayo Clinic echocardio-graphic database over an 11 year period, 78patients were identified with LFLG severeAS, defined as an aortic valve area<1.0cm2, stroke volume index<35 mL/m2,mean aortic gradient<40 mm Hg and anEF ≥50%, in whom there was at least 1other echo in the prior 5 years.Contradicting our preconceived notions,only 5% of these patients had evidence forhigh gradient severe AS before developingLFLG severe AS. Instead, over the preced-ing 5 years there was evidence for graduallyincreasing LV wall thickness and decreasingchamber size with hemodynamics charac-terized by a reduction in stroke volume andvalve area without ever going through aphase of high gradient AS (figure 3).

In the accompanying editorial,Drs Magne and Mohty refine the conceptof LFLG severe AS with normal EF, oftencalled “paradoxical” LFLG severe AS.They suggest that: “this study supports theconcept that paradoxical LFLG is notnecessarily a more advanced stage of thevalvular disease (ie, stenosis severity) butrather a more advanced stage of the ven-tricular disease”. A practical clinicalapproach to these patients is summarizedin figure 4.

The Education in Heart article in thisissue explains the concept of myocardialreperfusion injury and suggests that ische-mic preconditioning has been neglected aspotential therapy to protect against myocar-dial damage during cardiac surgery orwith ST segment elevation myocardialinfarction. (see page 1067) As with allEducation in Heart articles, CPD/CMEcredits are available if you answer theaccompanying multiple choice questions.

The Image Challenge case (see page1031) in this issue shows a rare conditionthat was mistaken for a more common diag-nosis, showing how imaging provided thedefinitive information needed for clinicalmanagement.

To cite Ribeiro AL, Otto CM. Heart 2015;101:991–992.

Heart 2015;101:991–992.doi:10.1136/heartjnl-2015-308188

Figure 3 Serial changes in (A) aortic valve area, p<0.001 for low-flow, low-gradient severeaortic stenosis (LFLG-sAS) vs normal-flow, high-gradient (NFHG)-sAS and for LFLG-sAS vsnormal-flow, low-gradient (NFLG)-sAS; (B) aortic valve area index, p<0.001 for LFLG-sAS vsNFHG-sAS and p=0.02 for LFLG-sAS vs NFLG-sAS; (C) aortic valve maximum velocity, p<0.001 forLFLG-sAS vs NFHG-sAS and p=0.52 for LFLG-sAS vs NFLG-sAS; and (D) aortic valve meangradient, p<0.001 for LFLG-sAS vs NFHG-sAS and p=0.02 for LFLG-sAS vs NFLG-sAS, as afunction of time, according to the AS group. Bars represent 95% CI for estimate at each timepoint. Time 0 indicates the index echocardiogram. The percentages of patients withechocardiograms at the various time intervals are tabulated below the figure.

Figure 4 Practical algorithm describing the daily clinical practice diagnosis of ‘true’ paradoxicallow-flow, low-gradient (LFLG) severe aortic stenosis (AS). In the presence of echocardiographicfindings suspecting (Step 1) the presence of paradoxical LFLG, all values should be meticulouslyconfirmed and validated using alternative methodologies (Step 2) in order to address the threequestions in boxes. In case of doubt or inconclusive echocardiographic results, other imagingmodalities such as low dose dobutamine transthoracic echocardiography (TTE), CT with aorticvalve calcium score assessment or cardiac magnetic resonance (CMR) may be used. When allfindings are concordant, the apparent ‘paradox’ should be explained by concomitantpathophysiological features (Step 3). Ultimately, in case of obvious symptomatic ‘true’ paradoxicalLFLG, we should refer to current practice guidelines and surgical intervention or transcathetervalve intervention (TAVI) should be discussed by the ‘Heart Team’. AVA, aortic valve area; AVAi,indexed aortic valve area; LVOT, LV outflow tract; MPG, mean pressure gradient; MR, mitralregurgitation; SVi, stroke volume index; TR, tricuspid regurgitation.

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