Systolic Time Intervals in the Diagnosis of Heart Failure in Emergency Departement

Systolic Time Intervals: a Diagnostic Tool of Acute Heart Failure in Emergency Departement Settings

the gold standard for the diagnostic of acute heart failure is based on clinical, biological (BNP levels) and echocardiographic findings, but still in some cases, the diagnosis is difficult and requires further investigations.

BNP dosages and echocardiography are not always available in many medical centers, especially in emergency departements, and are expensive.

we investigated the use of alternative methods, such as the systolic time intervals (STI), in the diagnosis of acute heart failure (AHF) in emergency departement patients consulting for dyspnea.

AHF is a common cause for dyspnea, but still hard to diagnose. in emergency departements, physicians dispose of a variety of techniques helping them to identify patients with acute onset dyspnea due to cardiac causes and allowing them to initiate the appropriate therapeutics.

techniques such as the N type brain natriuretic peptid (NT BNP) dosages and echocardiography, in addition to the clinical exam, are efficient in these cases but they encounter many problems:

• the BNP dosages are non-conclusive in some cases (grey zone) and must be repeated wich takes time.
• echocardiography is operator - dependent technique and could be misleading in some conditions.
• both BNP and echocardiography are expensive and not found in many emergency structures, especially in poor countries.

all the arguments pushed us to investigate other simpler and cheaper techniques to apply in these conditions.

STI is an old technique based on the recording of two parameters: electrocardiogram and phonocardiogram, and from them measuring the different systolic intervals:

• pre-ejection period (PEP): defined as the interval between the beginning of the QRS wave and the first heart sound (B1).
• electro-mechanic activation time (EMAT): defined as the interval between the two heart sounds B1 and B2
• the PEP / EMAT time in acute onset heart failure, the conduction times are increased, due to tissular lesions, which prolong the PEP, also the myocardial contractility is deficient and the heart puts less time to eject the blood volume which decrease the EMAT and in summary the PEP/EMAT is increased significatively.

in this study protocol, we aimed to investigate the diagnostic performance of STI compared to conventional methods in the diagnosis of acute heart failure in emergency department settings.

Inclusion Criteria:

• non traumatic dyspnea
• age more than 18 years old.

Exclusion Criteria:

• ECG diagnostic for acute myocardial infarction or ischemic chest pain within the prior 24 hours
• history of a heart transplant
• pericardial effusion
• chest wall deformity suspected of causing dyspnea
• coma, shock,Mechanical Ventilation, vasopressor drugs
• arrhythmia serious and sustained, pace maker severe mitral valve disease, severe pulmonary arterial hypertension
• renal failure with creatinine >350micromol/l