a b s t r a c t

Introduction: diagnostic sensitivity and specificity of standard electrocardiogram (ECG) in Acute pulmonary embolism are low. Presence of findings of concomitant right ventricular strain suggests that the use of right-sided ECG recording may be helpful in APE. This study was aimed to investigate the diagnostic usefulness of right-sided ECG in APE. Materials and methods: Patients determined to be at moderate and high risk according to Wells’ Criteria and who underwent pulmonary computed tomography angiography imaging were included in the study. Right-sided ECG recording was performed along with standard ECG recording during the first examination of patients.

Results: A total of 117 patients were included in the study. Sixty-four patients (55%) were female. The mean age

was 62 +- 16 years for men and 64 +- 17 years for women. Acute pulmonary embolism was detected in 75 pa- tients (64%) by pulmonary computed tomography angiography. Although T-wave inversions were most com- mon in leads V₂ to V₄ (sensitivity, 31%) in standard ECG of patients with APE, right-sided ECG showed T-wave inversions most commonly in V₃R to V₆R (sensitivity, 64%) and ST-segment elevations in V₃R to V₆R (sensitivity, 29%). In APE patients with hypotensive shock, T-wave inversions in leads III and aVF (sensitivity, 57%) in standard ECG and T-wave inversions in V₃R to V₆R (sensitivity, 57%) and ST-segment elevations in V₃R-V₆R (sensitivity, 50%) in right-sided ECG were most commonly observed.

Conclusion: The right-sided ECG has a higher sensitivity than standard ECG for the diagnosis of APE. In patients with clinical APE suspicion, routine use of right-sided ECG along with standard ECG in the first evaluation can be useful.

(C) 2016

1. Introduction

acute pulmonary embolism is one of the most common causes of cardiovascular-cause mortality. The mortality can reach 15% especially in high-risk patients [1]. Mortality reduction is possible with Prompt diagnosis and treatment. Patients with APE are admitted to the emergency department (ED) with nonspecific symptoms such as shortness of breath, chest pain, and syncope, and electrocardiogram (ECG) is the first referenced diagnostic tool during the first examination of these patients, although it has low sensitivity and specificity [1-3]. (See Fig. 1).

The standard ECG findings in APE more often depend on the strain and ischemia that occur in the right ventricle and sinus tachycardia; S1Q3T3 pattern, right bundle-branch block, and T-wave inversions in precordial leads have been identified most frequently. In addition, atrial

* Corresponding author at: Department of Emergency Medicine, Antalya Training and Research Hospital, 07100 Antalya, Turkey. Tel.: +90 507796560.

E-mail address: [email protected] (N. Kozaci).

fibrillation, supraventricular tachycardia, ventricular tachycardia, axis deviation changes (right or left axis deviation), changes in P-wave mor- phology (P pulmonale), QRS complex changes (low QRS voltage), repo- larization abnormalities (inverted T waves, ST depression, or ST elevation), or prolongation of the QT interval can be seen [1-3].

Electrocardiographic studies on APE have been performed with standard ECG and included left chest leads. There are very few reports on right-sided ECG, including the right chest leads, in the literature [4,5]. This study was aimed to investigate the diagnostic usefulness of right-sided ECG in APE (See Fig. 2).

1. Materials and methods

This prospectively planned study was initiated after obtaining hospi- tal ethics committee approval. Patients who were admitted to the hos- pital ED with complaints of shortness of breath, chest pain, and syncope and who were suspected to have moderate- and high-risk APE according to Wells’ Criteria were enrolled in the study. Patients who had a history of pulmonary embolism, who were diagnosed as

http://dx.doi.org/10.1016/j.ajem.2016.04.025

0735-6757/(C) 2016

Fig. 1. Standard ECG of a 55-year-old male patient admitted to ED with chest pain. He had hypotensive shock. He had high risk of APE according to Wells’ Criteria. Right ventricular strain findings was detected by ECHO. In addition, deep vein thrombosis in his left leg was detected by Doppler ultrasonography. Thrombolytic therapy was given immediately. After vital signs became stable, PCTA imaging was performed, and bilateral main pulmonary artery embolism was detected.

having APE in another institution, who could not undergo pulmonary computed tomography angiography (PCTA) imaging, and who did not consent were excluded from the study.

Standard ECG and right-sided ECG recordings were obtained at ini- tial examination of the patients enrolled in the study. Simultaneously, arterial blood pressure, respiratory rate, pulse rate, temperature, and oxygen saturation values were measured. Blood samples were obtained through intravenous lines and D-dimer, troponin I (0.02-0.06 ng/mL), blood urea nitrogen, creatinine, Na, K, Cl, aspartate aminotransferase, al- anine Aminotransferase, and complete blood count tests were ran. Blood gases were studied from arterial samples obtained through Radial artery puncture. Echocardiography (ECHO) was performed by cardiolo- gist. Bedside ECHO was performed for unstable patients; otherwise, ECHO was performed in the cardiology department. Forty-six patients with APE underwent ECHO. Once stabilized, patients underwent PCTA imaging.

Electrocardiographic analysis

Standard 12-lead ECG was obtained during the first examination of the patients. Right-sided ECG recordings were performed simulta- neously. Electrocardiogram was recorded at a paper speed of 25 mm/s and standard deflection amplitude of 10 mm/mV.

Right-sided ECG recording was performed as a mirror image of stan- dard left-sided ECG recording.

V₁R: Fourth intercostal space, left sternal border. V₂R: Fourth intercostal space, right sternal border.

V₃R: The middle of the distance between V₂R and V₄R. V₄R: Fifth intercostal space, right midclavicular line.

V₅R: Right anterior axillary line, horizontally even with V₄R and V₆R. V₆R: Right midaxillary line, horizontally even with V₄R and V₅R. Relocation was not made to arm and leg electrodes.

The heart rate, rhythm, QRS axis, P wave, and presence of right bundle-branch block; S1Q3T3 pattern; T-wave inversions in leads III and aVF; T-wave inversions in leads V₂ to V₄; ST-segment elevation in leads aVR, III, and V₁; and QR pattern in lead V1 were evaluated on stan- dard ECG recording.

The presence of ST-segment elevations or depressions, T-wave in- versions, and QS and QR patterns was evaluated on right-sided ECG re- cording. A depth of at least 1 mm from the isoelectric line for T-wave inversion and a height of at least 0.5 mm from isoelectric line for ST- segment elevation were considered as limits in right-sided ECG. Q- wave length was considered as more than 2 mm for QS and QR patterns.

Transthoracic ECHO

Transthoracic ECHO was performed by cardiologists using ECHO de- vice with a 3.5-MHz probe. Echocardiography finding was accepted pos- itive for right ventricular strain in the presence of right ventricular dilatation, hypokinesia, paradoxical movement of interventricular

Fig. 2. The right-sided ECG of the same patient described in Fig. 1.

septum, end-diastolic diameter increase and tricuspid insufficiency, McConnell’s sign, and “D” sign.

Pulmonary computed tomography angiography

Pulmonary computed tomography angiography imaging was per- formed in patients with suspected APE and moderate and high risks ac- cording to Wells’ Criteria. For this purpose, Hitachi ECLOS multislice CT scanner system was used. Eighty milliliters of intravenous contrast ma- terial was administered through antecubital intravenous line. Early ar- terial phase images were obtained 10 to 15 seconds after power injection. Images were evaluated by a radiologist. Pulmonary computed tomography angiography results were reported as positive and negative embolism. Embolism was grouped into subsegmental, segmental, and main pulmonary artery.

Cardiac troponin I testing

Cardiac troponin I testing was performed using ADVIA Centaur Ana- lyzer (Siemens) system by immunoassay method. The normal values re- ported in Healthy adults are 0.02 to 0.06 ng/mL.

Statistical analysis

All statistical analysis was performed using SPSS 21 statistical soft- ware. Categorical variables were expressed as numbers or percentages; and continuous variables, as medians +- SD. Categorical variables were compared using the ?² test. Receiver operating characteristic curves were used to assess the usefulness of measurements and to determine sensitivity and specificity of the test. Pb .05 was considered statistically significant.

1. Results

This study was performed prospectively between October 1, 2014, and September 30, 2015. A total of 117 patients were included in the study. Fifty-three patients (45%) were male, and 64 (55%) were female. The mean age was 62 +- 16 years for men and 64 +- 17 years for women. The patients were admitted to the emergency with shortness of breath mostly. The most frequent risk factors for APE were immobilization (47%) and history of surgery (22%) (Table 1).

Embolism was not detected in 42 patients (36%) by PCTA. Acute pul- monary embolism was detected in a total of 75 patients (64%). The

Table 1

Baseline characteristics of the study patients

embolism was subsegmental in 13 patients (11%) and segmental in 37 patients (32%) and was in main pulmonary artery in 25 patients (21%). Of patients diagnosed as having APE, 21 patients (28%) had normal sinus rhythm, 41 (55%) had sinus tachycardia, and 13 (17%) had atrial

fibrillation.

Although T-wave inversions were most common in leads V₂ to V₄ (sensitivity, 31%) in standard ECG of patients with APE, right-sided ECG showed T-wave inversions most commonly in V₃R to V₆R (sensitiv- ity, 64%) (Table 2).

Hypotensive shock was identified in 14 patients (19%) with APE. In APE patients with hypotensive shock, T-wave inversions in leads III and aVF (sensitivity, 57%) in standard ECG and T-wave inversions in V₃R to V₆R (sensitivity, 57%) and ST-segment elevations in V₃R to V₆R (sensitivity, 50%) in right-sided ECG were most commonly observed (Table 3).

Forty-six patients with APE underwent ECHO. In 29 (63%) of these patients, right ventricular strain findings were observed. In patients with positive ECHO findings, T-wave inversions (sensitivity, 48%) in leads V₂ to V₄ in standard ECG and T-wave inversions (sensitivity, 72%) in V₃R to V₆R and ST-segment elevations (sensitivity, 38%) in V₃R to V₆R in right-sided ECG were most commonly determined (Table 3). Troponin I levels were measured in 61 patients(80%) with detected emboli. In 23 (38%) of these patients, troponin I level was above the nor- mal limit. In patients with positive troponin I levels, T-wave inversions in leads V₂ to V₄ (sensitivity, 57%) in standard ECG and T-wave inver- sions in V₃R to V₆R (sensitivity, 78%) and ST-segment elevations in V₃R to V₆R (sensitivity, 38%) in right-sided ECG were most commonly

observed (Table 3).

1. Discussion

Chest pain, shortness of breath, and syncope are frequent causes of ED admissions and can point to potentially fatal illnesses such as acute myocardial infarction (MI), aortic dissection, and APE. In the evaluation of these patients, ECG examination is first referenced method in the ED. Although ECG changes are specific in acute MI, they are usually nonspe- cific in case of APE. The sensitivity of ECG in ruling out the diagnosis of APE is low, and ECG is completely normal in 20% of patients [6]. Electro- cardiographic findings are often seen in severe cases. Sinus tachycardia may be the only symptom in mild cases, but it is present in 40% of pa- tients [7].

In our study, sinus tachycardia, incomplete right bundle-branch block, S1Q3T3 complex, ST-segment elevations in leads aVR, III, and V₁ and T-wave inversions in leads III to aVF were identified common find- ings in standard ECG of patients with APE. However, the highest sensi- tivity was detected in T-wave inversions (anterior ischemic pattern)

in leads V₂ to V₄ in the standard ECG. Besides being the most common

Variables

Male, n (%) 53 (45%)

Mean age (y) 62 +- 16

Female, n (%) 64 (55%)

Mean age (y) 64 +- 17

Complaints of the patients, n (%)

Dyspnea 76 (65%)

Chest pain 32 (27%)

Syncope 4 (3.4%)

Weakness 3 (2.6%)

Cough 1 (1%)

Hemoptysis 1 (1%)		ity, and positive predictive value in right ventricular MI [8]. Although QR
isk factors for acute pulmonary embolism, n (%) pattern in leads V3R to V6R, QS pattern in leads V3R to V6R, and ST-
Immobilization 55 (47%) History of surgery 26 (22%) Heart failure 22 (19%) Deep vein thrombosis 17 (15%)		segment elevations in leads V3R to V6R were common findings in pa- tients with APE, the highest sensitivity (64%) was detected in T-wave in- versions in leads V3R to V6R. Compared with the sensitivity of T-wave
Malignancy	17 (15%)	inversions in leads V2 to V4 (31%) that show anterior ischemic pattern,
Chronic lung disease	15 (13%)	the sensitivity of T-wave inversions in leads V3R to V6R (64%) was
Ischemic heart disease Oral contraceptive use	10 (9%) 2 (3%)	more than twice. This result shows that right-sided ECG has a higher sensitivity for the diagnosis of APE compared to standard ECG.

finding in many studies, T-wave inversions in leads V₂ to V₄ that show anterior ischemic pattern are seen at a higher rate in patients with mas- sive embolism [1,2].

Presence of findings of concomitant right ventricular strain suggests that the use of right-sided ECG recording may be helpful in APE. Right- sided ECG recording is a mirror image of standard left-sided 12-lead ECG recording and important in terms of showing the right ventricular wall infarction. ST-segment elevations and necrosis (QS, QR pattern) in the right precordials (V₃R-V₅R) have a very high sensitivity, specific-

R

Table 2

Comparison of the patients’ PCTA results with their ECG findings

Standard ECG

PCTA results Sensitivity (%) Specificity (%) 95% CI P

APE (+), n = 42 APE (-), n = 75

Negative T waves in leads V2-V4	3	23	31	93	0.516-0.719	.003
Right bundle-branch block	4	23	31	90	0.503-0.709	.009
ST-segment elevation in leads aVR, III, and V1	2	18	24	95	0.493-0.699	.008
Negative T waves in leads III and aVF	1	17	23	98	0.499-0.704	.004
S1Q3T3 complex	1	11	15	98	0.456-0.667	.036
QR pattern in lead V1	0	6	8	100	0.433-0.647	.06
The right-sided ECG Negative T waves in leads V3R-V6R	5	48	64	88	0.672-0.849	.001
ST-segment elevation in leads V3R to V6R	1	22	29	98	0.535-0.734	.001
QS pattern in leads V3R-V6R	0	20	27	98	0.521-0.722	.001
QR pattern in leads V3R-V6R	0	12	16	100	0.476-0.684	.006

Symptoms of right ventricular strain and hypotension occur de- pending on the severity of APE. Failure to provide sufficient oxygen in case of right ventricular strain may result in right ventricular ischemia or infarction. The European Society of Cardiology and the American Heart Association proposed a 3-level damage risk rating in APE based on hemodynamic status with presence of right ventricular dysfunction or myocardial injury. Accordingly, there is continuous systemic arterial hypotension in high-risk (or massive) APE. In intermediate- risk (or submassive) APE, there is no hypotension, although there is RVD or myocardial injury. Finally, there are no markers of hypotension and RVD or myocardial injury in low-risk APE [9].

Electrocardiographic changes are seen in massive embolism by 94% [10]. Atrial arrhythmias, incomplete or complete right bundle-branch block, S1Q3T3 complex with pseudoinfarction pattern in leads DIII to aVF and T-wave inversions in left precordial leads V₁ to V₄ were detect- ed in fatal cases [7,11]. ST-segment elevations that can mimic acute cor- onary syndrome were observed in lead V₁, showing the anterior wall of right ventricle, and lead III, showing inferior area of right ventricle [1,3]. In addition, ST-segment elevation in Lead aVR with ST-segment depres- sions in leads V₁ and V₄ to V₆, ST-segment elevations in leads III and/or V₁/V₂ with ST-segment depression in leads V₄/V₅ to V₆, and ST-segment elevations in leads V₁ to V₃/V₄ were observed [12-14].

In our study, T-wave inversions in leads III and aVF (sensitivity, 57%) in standard ECG were observed most commonly in patients with detect- ed shock. Together with ST-segment elevations in leads V₃R-V₆R (sensi- tivity, 50%), T-wave inversions were detected in V₃R to V₆R (sensitivity, 57%) most commonly in right-sided ECG.

Table 3 Comparison of the standard and right sided ECG findings with the presence of hypotensive shock, ECHO findings, and positive troponin I

Hypotensive Findings of Positive

shock (+), ECHO (+), troponin I (+),

ST-segment elevation of more than 1 mm in lead V₄R is a reliable in- dicator of right ventricular MI, and the specificity and sensitivity of ST elevation in lead V₄R are higher than ST-segment elevation in lead V₁ in the diagnosis of Right ventricular infarction [15,16]. Similar to this finding, the sensitivity of ST-segment elevation in leads V₃R to V₆R (50%) was much higher compared to the sensitivity of ST-segment ele- vation in leads aVR, III, and V₁ (36%) in patients with shock in our study. Although right bundle-branch block, sinus tachycardia, McGinn- White sign (sign S1Q3T3), and T-wave inversions in leads V₁ to V₃ are seen in APE patients with RVD, the sensitivity and diagnostic accuracy of T-wave inversions in leads V₁ to V₃ in terms of showing the right ven- tricular dysfunction were higher [17,18]. In our study, likewise, the highest sensitivity was found in T-wave inversions in leads V₂ to V₄ (48%) in standard ECG of patients with positive ECHO findings. Howev- er, the sensitivity of T-wave inversions in leads V₃R to V₆R (72%) in right-sided ECG was found to be much higher. This result shows that right-sided ECG better demonstrates right ventricular strain and is

more sensitive in the assessment of RVD.

In a study evaluating the ECG parameters in predicting the myocar- dial damage in patients with APE, dextrogyria (60.1%), T-wave inver- sions in leads V₂ to V₄ (57.3%), S1Q3T3 (42.7%), and ST-segment elevation in lead V₁ (42.7%) were identified as the most common find- ings in patients with positive troponin levels [13]. In another study, cor- relation between plasma cardiac troponin level and number of T-wave inversions and ST-segment depressions was detected [19].

In our study, the highest sensitivity (57%) was detected in T-wave inversions in leads V₂ to V₄ in patients with positive troponin I levels. In contrast, high sensitivities were observed in T-wave inversions (78%) and ST-segment elevations (52%) in leads V₃R to V₆R in right- sided ECG. Right-sided ECG having a higher sensitivity compared to standard ECG may be due to right-sided ECG showing right ventricular ischemia better.

In conclusion, right-sided ECG has a higher sensitivity in the diagno- sis of APE due to better demonstration of right ventricle. ST-segment el-

evations and T-wave inversions in leads V R to V R in right-sided ECG

n = 14/75

n = 29/46

n = 23/61 3 6

Standard ECG, n (sensitivity/specificity)

S1Q3T3 complex	4 (29%/88%)	6 (20%/83%)	7 (30%/90%)	ing the severity of APE. Therefore, in the ED, routine use of right-sided
Negative T waves in leads III and aVF ST-segment elevation	8 (57%/85%) 5 (36%/79%)	12 (41%/94%) 10 (35%/88%)	8 (35%/82%) 10 (44%/87%)	ECG with standard ECG in the first evaluation of patients with clinical suspicion can be useful. Right-sided ECG leads can assist in the diagnosis of APE; these leads, however, should not be the sole diagnostic confir-
in leads aVR, III, and V1 Negative T waves in	5 (36%/70%)	14 (48%/76%)	13 (57%/84%)	matory test used in these patients. In fact, the ECG, including right-
leads V2-V4				sided ECG, is most often used in the pulmonary embolism-suspected
The right-sided ECG, n				patient to rule out cardiac issues.
(sensitivity/specificity)
ST-segment elevation	7 (50%/75%)	11 (38%/71%)	12 (52%/84%)
in leads V3R-V6R
Negative T waves in	8 (57%/34%)	21 (72%/35%)	18 (78%/40%) References

are common findings in moderate and high-risk patients. The sensitivity of right-sided ECG is high in the diagnosis of APE as well as in determin-

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leads V3R-V6R
QS pattern in leads V3R-V6R	2 (14%/70%)	8 (28%/71%)	3 (13%/60%)
QR pattern in leads V3R-V6R	4 (29%/87%)	7 (24%/82%)	5 (22%/87%)

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