What is the 60 60 rule for pulmonary embolism?

The 60/60 Rule in Pulmonary Embolism Diagnosis

When evaluating a possible pulmonary embolism (PE), doctors often rely on a combination of clinical signs, imaging, and echocardiography. One useful clue in transthoracic echocardiography (TTE) is known as the 60/60 sign—a subtle but telling indicator that can point toward acute PE, especially when other diagnostics are pending.

This sign combines two measurements from the echocardiogram: a pulmonary acceleration time (PAT) of less than 60 milliseconds and a tricuspid regurgitation (TR) jet gradient below 60 mmHg. Normally, the pulmonary acceleration time is longer—over 90 milliseconds—but in PE, the sudden blockage in the pulmonary arteries causes a rapid spike in pressure, shortening the PAT. Meanwhile, a TR gradient under 60 mmHg suggests that the right ventricle hasn’t had time to develop chronic high pressure, supporting the idea of an acute event rather than long-standing pulmonary hypertension.

While not every PE patient will show the 60/60 sign, its presence is highly specific. It’s particularly helpful in emergency settings where CT angiography—the gold standard—might be delayed or contraindicated. However, it’s important to remember that this sign has limited sensitivity; many patients with PE won’t meet both criteria. Therefore, it should be used as part of a broader clinical assessment, not in isolation.

Ultimately, the 60/60 rule is a clever echocardiographic shortcut—a hint in the right direction when time matters. It highlights how thoughtful use of bedside ultrasound can guide life-saving decisions without replacing comprehensive evaluation.