What is the definition of a peaked T wave (electrocardiogram abnormality)?

From the Guidelines

Peaked T waves are abnormally tall, narrow, and symmetric T waves on an electrocardiogram (ECG) that typically indicate hyperkalemia, a dangerous condition where potassium levels in the blood are too high. These T waves appear taller than normal (often >5mm in limb leads or >10mm in precordial leads), with a narrow base and pointed apex, resembling a tent or mountain peak. Hyperkalemia is the most common cause, with the height of the T wave often correlating with the severity of potassium elevation. Other potential causes include acute myocardial ischemia, Brugada syndrome, and early repolarization. Peaked T waves are an early warning sign that requires immediate medical attention, as hyperkalemia can progress to life-threatening arrhythmias. Treatment typically involves addressing the underlying cause, administering calcium gluconate to stabilize cardiac membranes, and using insulin with glucose, sodium bicarbonate, or potassium-binding resins to lower potassium levels. The physiological basis for peaked T waves involves altered cardiac cell repolarization due to extracellular potassium affecting membrane potential and accelerating phase 3 of the cardiac action potential 1.

Some key points to consider when evaluating T-wave abnormalities include:

• T-wave amplitude in limb leads is influenced by the frontal-plane T axis, which in turn is influenced by the QRS axis.
• In normal adults, the T-wave amplitude is most positive in lead V2 or V3.
• T-wave amplitudes for V2 from 1.0 to 1.4 mV have been listed as upper normal thresholds in men (up to 1.6 mV in the 18- to 29-year age group) and from 0.7 up to 1.0 mV in women 1.
• A number of terms such as peaked, symmetrical, biphasic, flat, and inverted are being used as appropriate qualitative T-wave descriptors.
• Interpreting isolated T-wave abnormalities is difficult and often the source of ambiguous and inaccurate statements.
• The inappropriate diagnoses of myocardial ischemia and infarction are common errors 1.

It is essential to consider the clinical context and other diagnostic findings when interpreting T-wave abnormalities, as the ECG is just one tool in the diagnosis and management of patients with suspected cardiac conditions. In patients suspected of having ACS on clinical grounds, marked (greater than or equal to 2 mm [0.2 mV]) symmetrical precordial T-wave inversion strongly suggests acute ischemia, particularly that due to a critical stenosis of the left anterior descending coronary artery (LAD) 1. The presence or absence of ST-segment elevation in the right ventricular or posterior chest leads also adds prognostic information in the presence of inferior ST-segment elevation, predicting high and low rates of in-hospital life-threatening complications, respectively 1.

Overall, peaked T waves are a significant finding on an ECG that requires prompt attention and further evaluation to determine the underlying cause and guide appropriate treatment. The most recent and highest quality study on this topic is from 2013, which provides updated guidelines for the management of patients with unstable angina/non-ST-elevation myocardial infarction 1. This study emphasizes the importance of considering the clinical context and other diagnostic findings when interpreting T-wave abnormalities and highlights the need for prompt attention and further evaluation in patients with peaked T waves.

From the Research

Definition of Peaked T Wave

• A peaked T wave is an electrocardiogram (ECG) abnormality that can be associated with hyperkalemia, as stated in studies 2, 3, 4, 5, 6
• The universal definition of a peaked T wave is still unclear, with low sensitivity and specificity, as mentioned in study 4
• Peaked T waves are characterized by an abnormal T-wave morphology, which can be encountered in various conditions, including hyperkalemia, early repolarization, and left ventricular hypertrophy (LVH), as discussed in study 3

Electrocardiographic Manifestations

• Peaked T waves are one of the most common ECG alterations in hyperkalemic patients, as reported in studies 2, 4, 5, 6
• Other ECG manifestations of hyperkalemia include widening of the QRS-complex, prolongation of the PR interval, flattening or absence of the P-wave, and a "sine-wave" appearance at severely elevated levels, as described in study 6
• The presence of peaked T waves is not exclusive to hyperkalemia and can be associated with other conditions, as mentioned in study 3

Predictive Value of Peaked T Waves

• Peaked T waves have been found to poorly predict serum potassium levels and hyperkalemia in patients with acute kidney injury, as reported in study 5
• The terminal T wave angle has been found to outperform the initial angle in predicting hyperkalemia in chronic kidney disease patients, with an optimal cutoff angle of 66.20°, as stated in study 4