In an obese patient with diastolic heart failure presenting with left‑sided chest pain and a ventricular paced rhythm, how should I evaluate for acute coronary syndrome?

Evaluating Acute Coronary Syndrome in Ventricular Paced Rhythm

In a patient with ventricular paced rhythm and chest pain, apply the modified Sgarbossa criteria to the ECG and obtain serial high-sensitivity troponins immediately—a score ≥3 points mandates emergent cardiac catheterization, while echocardiography should be performed urgently to assess for regional wall motion abnormalities if the ECG is non-diagnostic.

ECG Interpretation in Ventricular Paced Rhythm

The ventricular paced rhythm creates significant diagnostic challenges because the abnormal ventricular depolarization pattern obscures typical ischemic changes. 1 However, specific criteria can identify STEMI despite the paced rhythm:

Modified Sgarbossa Criteria (Use This Scoring System)

Apply the following point system—a total score ≥3 indicates acute MI: 1

• Concordant ST-segment elevation ≥1 mm in leads with a positive QRS complex = 5 points 1
• Concordant ST-segment depression ≥1 mm in leads V1-V3 = 3 points 1
• Discordant ST-segment elevation ≥5 mm in leads with a negative QRS complex = 2 points 1

If discordant ST-segment elevation ≥5 mm is present, also calculate the ST/S ratio—a ratio <−0.25 suggests acute MI even without reaching 3 points. 1

Critical Pitfall to Avoid

Segmental wall motion abnormalities on echo are not synonymous with acute ischemia in paced rhythm—they can occur from the pacing itself, making the ECG criteria and troponin dynamics essential for diagnosis. 1 Do not rely on echocardiography alone to rule out ACS in this population. 1

Serial Troponin Strategy

Obtain high-sensitivity cardiac troponin immediately at presentation and repeat at 3 hours. 1

Interpretation Algorithm

• If initial troponin is elevated, look for dynamic changes: 1

  • At lower troponin values near the 99th percentile, use absolute changes to define clinically significant rise/fall 1
  • At higher troponin values, a 20% relative change indicates acute injury 1

• In diastolic heart failure patients, troponin may be chronically elevated—the key is demonstrating a rising or falling pattern consistent with acute injury rather than chronic elevation. 1

Special Consideration for This Patient Population

Obesity and diastolic heart failure are both risk factors for coronary artery disease, and silent myocardial ischemia can precipitate acute decompensation of diastolic heart failure. 2, 3 In one study, 39% of patients hospitalized for acute diastolic heart failure without obvious ischemic symptoms had underlying coronary artery disease, and at least 28% had silent ischemia contributing to their presentation. 2

Echocardiography Role

Perform urgent echocardiography to assess for new regional wall motion abnormalities, but never delay treatment while waiting for the study. 1

• If chest pain is ongoing or prolonged (>45 minutes), the absence of wall motion abnormalities on echo excludes major myocardial ischemia. 1
• However, normal resting echo cannot rule out transient ischemia if chest pain was brief or has resolved. 1
• Strain imaging may reveal subtle abnormalities when visual assessment appears normal. 1

Contrast Echocardiography Consideration

Myocardial contrast echocardiography allows simultaneous assessment of wall motion and perfusion—patients with normal perfusion and function at rest have excellent outcomes, while perfusion defects identify high-risk patients. 1 However, this requires specialized expertise not typically available in emergency settings. 1

Management Algorithm Based on Findings

If Sgarbossa Score ≥3 or Positive Modified Criteria:

• Activate STEMI protocol immediately and proceed to emergent cardiac catheterization 1
• Administer aspirin 162-325 mg chewed 4
• Load P2Y12 inhibitor (ticagrelor 180 mg preferred) 4
• Initiate anticoagulation with heparin 4

If ECG Non-Diagnostic but Troponin Rising/Falling:

• Diagnose NSTEMI and proceed to early invasive strategy (cardiac catheterization within 24 hours) 1
• Initiate dual antiplatelet therapy, anticoagulation, beta-blocker, and high-intensity statin 1

If Both ECG and Initial Troponin Non-Diagnostic:

• Obtain serial troponins at 3 hours 1
• Perform urgent echocardiography to assess for wall motion abnormalities 1
• Consider stress testing or coronary CT angiography before discharge if troponins remain negative 1

Additional Diagnostic Considerations

Obtain a 12-lead ECG within 10 minutes of presentation and compare with any prior ECGs to identify new changes. 1, 5 Serial ECGs every 5-10 minutes can detect evolution of ischemic changes. 4

In hemodynamically unstable patients, echocardiography should be performed immediately following the 12-lead ECG to facilitate diagnosis. 1

Obesity-Specific Considerations

The obese patient with diastolic heart failure presents additional complexity—fluid redistribution and systemic congestion can mimic or mask ACS symptoms. 3 Maintain high clinical suspicion for ACS as a precipitant of acute decompensation, even when classic anginal symptoms are absent. 2, 3

Do not attribute chest pain solely to heart failure exacerbation without excluding ACS through the systematic approach outlined above. 2