Can Bradyarrhythmias Cause Elevated Troponin?

Yes, bradyarrhythmias can cause troponin elevation through supply-demand mismatch, though this is less common than with tachyarrhythmias. 1

Mechanism of Troponin Elevation in Bradyarrhythmias

Bradyarrhythmias cause myocardial injury through a distinct mechanism compared to tachyarrhythmias:

Supply-demand imbalance: Severe bradycardia reduces cardiac output and coronary perfusion, creating an oxygen supply-demand mismatch that leads to myocardial stress and troponin release 1
This represents type 2 myocardial infarction (myocardial injury from ischemia without coronary artery occlusion), not acute plaque rupture 1, 2
The Third Universal Definition of Myocardial Infarction explicitly lists "tachy-/brady-arrhythmias" as causes of troponin elevation related to supply/demand imbalance 1

When encountering troponin elevation with bradyarrhythmia, consider these key points:

Magnitude matters: Mild elevations (<2-3 times upper limit of normal) in bradyarrhythmias typically reflect rate-related stress rather than type 1 MI and generally do not require workup for acute coronary syndrome unless strongly suggested by clinical symptoms or ECG changes 2
Marked elevations (>5 times upper limit of normal) have high positive predictive value (>90%) for acute type 1 MI and warrant aggressive evaluation even in the presence of arrhythmia 2
Serial measurements are essential: Obtain troponins at 3-6 hour intervals to establish a rising/falling pattern characteristic of acute myocardial injury, as a single elevated value is insufficient for diagnosis 1, 2

Certain conditions associated with bradyarrhythmias have particular relevance:

Cardiac amyloidosis: Bradyarrhythmia may be the terminal event, and elevated cardiac troponins (especially troponin T) are independent predictors of mortality, with median survival of 6-8 months in patients with detectable values versus 21-22 months in those with undetectable levels 1
Complete heart block: Approximately one quarter of patients with cardiac sarcoidosis develop complete heart block, and troponin elevation may occur in this context 1

When bradyarrhythmia and elevated troponin coexist:

Obtain ECG immediately to assess for ST-segment changes, conduction abnormalities, or ischemic patterns beyond the arrhythmia 2
Assess for ischemic symptoms (chest pain, dyspnea, diaphoresis) and hemodynamic stability 2
Send serial troponins at 1-2 hour intervals using high-sensitivity assays if symptoms or ECG changes suggest ischemia, or if hemodynamically unstable 2
Rising/falling pattern with at least one value above the 99th percentile indicates acute myocardial necrosis 1

For troponin elevation with symptoms/ECG changes consistent with ACS: Intensive management and early revascularization are indicated 1, 2
Without objective evidence of myocardial ischemia: Observe in a chest pain unit or telemetry unit with serial ECGs and cardiac troponins at 3-6 hour intervals 1
Focus on treating the underlying bradyarrhythmia (pacing if indicated) when troponin elevation occurs without symptoms/ECG changes suggestive of ACS 2

Troponin elevation indicates myocardial injury but does not specify the cause - it requires clinical context for interpretation 1, 2
Chronic elevations (stable values) may indicate chronic myocardial injury rather than acute events, particularly in patients with structural heart disease or renal failure 1
Prognostic significance: Any troponin elevation carries independent prognostic significance with increased short- and long-term mortality risk, regardless of the mechanism 2, 3