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 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.

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.