ECG Solution: The missed match

Did you pick the right treatment based off the patient's ECGs?

Editor's note: We asked columnist Tom Bouthillet to pick a winner to this month's challenge and he wrote: "For this month's column I picked well known ECG expert Dr. Ken Grauer as the winner. Not only did he correctly reason that the patient was suffering a pulmonary embolism (and not ACS), he reminded me that persistent precordial S-waves are also associated with right heart strain! Several others also came up with the right answer (I especially appreciate the ones who took the time to explain their responses). Some suggested that diminished breath sounds are not associated with pulmonary edema. This surprised me, so I did some searching in the peer reviewed literature. Here's an excerpt from Clinical Characteristics of Patients with Acute Pulmonary Embolism. Am J Med. 2007. October; 120(10): 871–879:

'Lung examination was abnormal in 29% of patients with pulmonary embolism and no prior cardiopulmonary disease and 37% of all patients with pulmonary embolism. Crackles and decreased breath sounds were the most frequent lung findings. Rhonchi and wheezes occurred uncommonly.'

Thanks to everyone who participated in the discussion!" Read Dr. Grauer's diagnosis and others' in the comments block.

-->  Haven't read the initial case presentation? Read: ECG Challenge: The missed match

Let's take another look at the 12-lead ECG.

There was also a 15-lead ECG with lead V4 in the position of V4R and leads V5 and V6 in the position of leads V8 and V9.

This patient was suffering from a pulmonary embolism. In fact he suffered a so-called "saddle embolism," meaning that both sides of the pulmonary artery were affected.

The ECG is not particularly sensitive for pulmonary embolism, but some ECG abnormalities are associated with it. The most common of these is sinus tachycardia, which is not present in this case.

However, there are two findings on this ECG that point to PE. The first is called "S1Q3T3," meaning an S-wave in lead I, a Q-wave in lead III and an inverted T-wave in lead III. This may only be present in 10 percent of patients with PE.1

In addition, there are inverted T-waves in leads V1 and V2. Both of these findings are associated with acute right heart strain (note that the S-wave in lead I is associated with a right axis deviation in the frontal plane).

A. "S1Q3T3" phenomenon B. Inverted T-waves in leads V1 and V2 C. The "clot busting" drug tPA (alteplase) that saved the patient's life D. CT scan showing the "saddle embolism"

Negative T-waves can be associated with both PE and ACS. However, when you have a negative T-wave in both lead III and lead V1, PE is far more likely than ACS.2

The patient received an emergent CT scan, which diagnosed the pulmonary embolism. Due to the patient's shortness of breath and the severity of the emboli, the patient was given the clot-busting drug tPA (alteplase).

The EMS crew saw the patient later in the day, and he was doing much better. The shortness of breath was completely gone, and the patient was pink, warm and dry. Many patients with severe PE aren't so fortunate!


1. Marchik et al. 12-Lead ECG Findings of Pulmonary Hypertension Occur More Frequently in Emergency Department Patients With Pulmonary Embolism Than in Patients Without Pulmonary Embolism. Ann Emerg Med. 2010 Apr;55(4):331-5.

2. Kosuge et al. Electrocardiographic Differentiation Between Acute Pulmonary Embolism and Acute Coronary Syndromes on the Basis of Negative T Waves. Am J Cardiol. 2007 Mar 15;99(6):817-21.

I'd like to acknowledge Stephen Smith, M.D., from Dr. Smith's ECG Blog for finding these excellent references on the ECG abnormalities associated with PE.

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