Findings on electrocardiogram may hint that pulmonary embolism (PE) is present when interpreted in the proper context and lead to definitive imaging tests. However, it would be useful to know if electrocardiographic (ECG) abnormalities also occur in patients with pneumonia and whether these are similar to ECG changes with PE. The purpose of this investigation was to determine ECG findings in patients with pneumonia. We retrospectively evaluated 62 adults discharged with a diagnosis of pneumonia who had no previous cardiopulmonary disease and had electrocardiogram obtained during hospitalization. The most prevalent ECG abnormality, other than sinus tachycardia, was minor nonspecific ST-segment or T-wave changes occurring in 13 of 62 (21%). Right atrial enlargement occurred in 4 of 62 (6.5%). QRS abnormalities were observed in 24 of 62 (39%). Right-axis deviation and S 1 S 2 S 3 were the most prevalent QRS abnormalities, which occurred in 6 of 62 (9.7%). Complete right bundle branch block and S 1 Q 3 T 3 pattern occurred in 3 of 62 (4.8%). ECG abnormalities that were not present within 1 month previously or abnormalities that disappeared within 1 month included left-axis deviation, right-axis deviation, right atrial enlargement, right ventricular hypertrophy, S 1 S 2 S 3 , S 1 Q 3 T 3 , low-voltage QRS complexes, and nonspecific ST-segment or T-wave abnormalities. In conclusion, electrocardiogram in patients with pneumonia often shows QRS abnormalities or nonspecific ST-segment or T-wave changes. ECG findings are similar to ECG abnormalities in PE and electrocardiogram cannot assist in the differential diagnosis.
The clinical importance of electrocardiogram in pneumonia relates to the differential diagnosis of pneumonia and pulmonary embolism (PE). Findings on electrocardiogram may hint that PE is present when interpreted in the proper context and lead to definitive imaging tests. However, it would be useful to know if electrocardiographic (ECG) abnormalities also occur in patients with pneumonia and whether they are similar to ECG changes with PE. The role of electrocardiogram in pneumonia has been sparsely studied. Therefore, the purpose of this investigation was to determine ECG findings in patients with pneumonia.
Methods
Hospitalized patients with a discharge diagnosis of pneumonia from January 2007 to December 2011 were identified by International Classification of Diseases, Ninth Edition, Clinical Modification codes 480 to 488. Medical records of these patients were reviewed. This investigation was approved by the institutional review boards of the participating hospitals (St. Mary Mercy Hospital, Livonia, Michigan; St. Joseph Mercy Oakland Hospital, Pontiac, Michigan).
Included patients were adults (≥18 years old) discharged with a diagnosis of pneumonia who had an electrocardiogram obtained during that hospitalization. All patients had chest x-ray showing a pulmonary parenchymal abnormality and all were treated with antibiotics. None received therapeutic doses of anticoagulants. Excluded patients were those with previous or current illness of coronary heart disease, cardiomyopathy, myocarditis, valvular heart disease, hypertension, chronic obstructive pulmonary disease, emphysema, chronic interstitial fibrosis, chronic bronchial asthma, or PE. Patients with previous atrial fibrillation were also excluded as were patients who previously showed ECG abnormalities on admission for pneumonia.
Electrocardiograms were read by the principal investigator (P.D.S.) according to criteria listed in Table 1 .
| Right atrial enlargement | P wave ≥0.25 mV (2.5 mm) in extremity leads or >0.15 mV in lead V 1 |
| Right-axis deviation | Mean frontal plane QRS electrical axis >90° |
| Left-axis deviation | Mean frontal plane QRS axis equal or leftward of −30° |
| S 1 S 2 S 3 pattern | S waves in leads I, II, and III ≥0.15 mV (1.5 mm) in each lead |
| S 1 Q 3 T 3 pattern | S wave in lead I and Q wave in lead III >0.15 mV (1.5 mm) with inversion of T wave in lead III |
| Clockwise rotation | Shift in transition zone (R = S) in precordial leads. Usually a shift to the lead V 4 position or further leftward is considered clockwise rotation. For this study, a shift in the transition zone to lead V 5 was analyzed to avoid problems of interpretation that may occur with minor errors of precordial electrode position. |
| Incomplete right bundle branch block | QRS duration 0.10–0.11 second and terminal QRS forces directed rightward and anteriorly causing S wave in lead I and R wave in lead V 1 |
| Complete right bundle branch block | QRS duration ≥0.12 second with terminal QRS forces directed rightward and anteriorly causing S wave in lead I and R wave in lead V 1 |
| Left bundle branch block | QRS ≥0.12 second with neither q nor S wave in lead I, aVL, or V 6 and notched R in these leads |
| Right ventricular hypertrophy | R wave in lead V 1 >0.5 mV (5 mm) or R/S ratio in lead V 1 >1 |
| Left ventricular enlargement | R wave in lead aVL >11 mm, or R wave in leads V 4 , V 5 , V 6 >26 mm, or R wave in lead V 5 or V 6 plus S wave in lead V 1 >35 mm |
| Low voltage QRS complexes | Overall QRS ≤0.5 mV (5 mm) in all limb leads |
| ST-segment depression | ST-segment depression ≥0.05 mV (0.5 mm) in any lead except aVR |
| T-wave inversion or flattening | Present if occurred in any lead except lead aVL, III, aVR, or V 1 |
Results
From January 2007 to December 2011, 2,593 patients had a discharge diagnosis of pneumonia. Of these, 2,487 had previous cardiopulmonary disease or had no electrocardiogram obtained during hospitalization. Of 106 patients with a discharge diagnosis of pneumonia and no previous cardiopulmonary disease who had an electrocardiogram, detailed review suggested that in 21 patients pneumonia may not have been present. In 23 patients, previous electrocardiograms showed ≥1 abnormality during hospitalization for pneumonia; therefore, these patients were excluded. Therefore, the sample consisted of 62 patients with pneumonia, no previous cardiopulmonary disease, and electrocardiograms with findings not known to be present previously. Demographic and clinical findings are listed in Table 2 .
| Variable | |
|---|---|
| Age (years), mean ± SD | 56 ± 20 |
| Women | 35 (57%) |
| White | 49 (79%) |
| Black | 10 (16%) |
| Cough | 44 (71%) |
| Productive cough | 30 (48%) |
| Leukocytosis | 33 (53%) |
| Fever | 35 (56%) |
| Rales | 26 (42%) |
| Sputum culture positive ⁎ | 19 (31%) |
| Ventilator dependent | 4 (6.5%) |
| Died | 4 (6.5%) |
⁎ Staphylococcus species in 5, mixed flora in 4, Streptococcus species in 2, Pseudomonas species in 2, fungus in 2, Haemophilus influenza in 1, Legionella species in 1, Serratia and Enterococcus species in 1, and atypical Mycoplasma species in 1.
Electrocardiogram was abnormal in 49 of 62 patients (79%) with pneumonia ( Table 3 ). The most prevalent ECG abnormality, other than sinus tachycardia, was minor nonspecific ST-segment and/or T-wave changes, occurring in 13 of 62 (21%). At least 1 QRS abnormality occurred in 24 of 62 (39%). Right-axis deviation and S 1 S 2 S 3 were the most prevalent QRS abnormalities, which occurred in 6 of 62 (9.7%). Right atrial enlargement occurred in 4 of 62 (6.5%). Complete right bundle branch block and S 1 Q 3 T 3 pattern occurred in 3 of 62 (4.8%).
| Electrocardiographic Finding | |
|---|---|
| Normal electrocardiogram | 13 (21%) |
| Rhythm disturbances | 40 (65%) |
| Sinus tachycardia | 33 (53%) |
| Atrial fibrillation | 3 (4.8%) |
| Atrial premature contractions | 4 (6.5%) |
| Ventricular premature contractions | 5 (8.1%) |
| Atrioventricular conduction abnormalities | |
| First-degree atrioventricular block | 2 (3.2%) |
| P wave | |
| Right atrial enlargement | 4 (6.5%) |
| QRS abnormalities | 24 (39%) |
| Right-axis deviation | 6 (9.7%) |
| Left-axis deviation | 4 (6.5%) |
| S 1 S 2 S 3 | 6 (9.7%) |
| S 1 Q 3 T 3 | 3 (4.8%) |
| Complete right bundle branch block | 3 (4.8%) |
| Right ventricular hypertrophy | 1 (1.6%) |
| Possible old infarction ⁎ | 1 (1.6%) |
| Low voltage (frontal plane) | 2 (3.2%) |
| Left ventricular hypertrophy | 1 (1.6%) |
| Left bundle branch block | 1 (1.6%) |
| Primary ST-segment and/or T-wave abnormalities | 13 (21%) |
| ST-segment depression | 2 (3.2%) |
| T-wave flattening or inversion | 4 (6.5%) |
| ST-segment and T-wave changes | 7 (11%) |
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