What is the significance of a left ventricular global longitudinal strain of –15% and how should it be managed?

Significance and Management of GLS -15%

A left ventricular global longitudinal strain of -15% indicates mild subclinical systolic dysfunction that requires close monitoring and consideration of guideline-directed medical therapy, even when ejection fraction appears normal. 1

Understanding the Measurement

• GLS values < -16% indicate mild depression of global longitudinal strain, placing your measurement of -15% in the abnormal range that signals early myocardial impairment. 1

• This finding is more sensitive than ejection fraction for detecting early cardiac dysfunction, often identifying abnormalities months before EF declines become apparent. 1

• The measurement reflects dysfunction of subendocardial longitudinal myocardial fibers, which are particularly vulnerable to early cardiac injury and ischemia. 1

• Normal GLS ranges from -18% to -22%, with values between -16% to -18% considered borderline, making -15% definitively abnormal. 2

Clinical Significance and Risk Stratification

• Patients with abnormal GLS but normal ejection fraction have significantly increased cardiovascular risk, with studies showing a 2.4-fold increased hazard for vascular events compared to those with normal GLS. 3

• A GLS of -15% is associated with increased risk of heart failure hospitalization and all-cause mortality in community-based cohorts, independent of other risk factors. 3, 4

• This level of dysfunction indicates early stage B heart failure (structural heart disease without symptoms), which warrants intervention to prevent progression. 2

Immediate Diagnostic Actions

• Repeat echocardiography within 2-3 weeks using the same equipment vendor to confirm the measurement, as vendor variability can affect absolute GLS values by several percentage points. 1, 5

• Obtain a comprehensive clinical history focusing on:

  • Recent viral illness (including COVID-19), which can cause transient myocardial dysfunction 1
  • Exposure to cardiotoxic chemotherapy (anthracyclines, trastuzumab), where GLS <-19% predicts subsequent cardiotoxicity 1
  • History of chest radiation therapy 1
  • Cardiovascular risk factors (hypertension, diabetes, coronary disease) 3
  • Athletic training status, as elite endurance athletes may have GLS values of -16% to -18% as physiologic adaptation 1

• Check cardiac biomarkers (troponin, BNP/NT-proBNP) to assess for active myocardial injury or elevated filling pressures. 1

• Assess diastolic function parameters on the echocardiogram, particularly E/e' ratio and left atrial volume index, as diastolic dysfunction commonly accompanies reduced GLS. 1, 6

Management Strategy

If Patient is Asymptomatic with No Known Cardiac Disease:

• Initiate serial GLS monitoring every 3-6 months to detect progression, as worsening GLS over time indicates pathological deterioration requiring intervention. 5

• Consider cardiac MRI to evaluate for underlying structural disease, including:

  • Myocardial fibrosis or scarring (late gadolinium enhancement) 1
  • Infiltrative cardiomyopathies (amyloidosis, sarcoidosis) 1
  • Inflammatory myocarditis 1

• Optimize cardiovascular risk factor control (blood pressure <130/80 mmHg, LDL <70 mg/dL, HbA1c <7% if diabetic). 3

If Patient Has Heart Failure Risk Factors or Symptoms:

• Initiate guideline-directed medical therapy immediately, starting with:

  • ACE inhibitor or ARB (e.g., lisinopril 2.5-5 mg daily, titrate to target dose) 1, 5
  • Beta-blocker (e.g., carvedilol 3.125 mg twice daily, titrate to target dose) 5
  • Consider SGLT2 inhibitor even if non-diabetic, as these improve outcomes in early dysfunction 7

• Do not delay therapy based on asymptomatic low blood pressure (systolic BP 80-100 mmHg), as guideline-directed medications improve mortality regardless of baseline blood pressure. 7

If Patient Has Recent Chemotherapy Exposure:

• A relative reduction in GLS ≥15% from baseline is considered abnormal and predictive of subsequent cardiotoxicity requiring intervention. 1

• Consider cardioprotective therapy with ACE inhibitors or beta-blockers, which have been shown to prevent progression when started early. 1

• Increase monitoring frequency to every 3 months during and after cardiotoxic therapy. 1

Important Caveats and Pitfalls

• GLS values are not applicable to patients currently receiving inotropic agents or mechanical circulatory support, as these interventions artificially alter the measurement. 1

• In post-cardiac surgery patients, septal strain may be artifactually reduced due to paradoxical septal motion, making the measurement unreliable. 5

• Isolated abnormal GLS with excellent image quality should prompt review of the primary data before proceeding with extensive additional testing, as technical factors can occasionally produce spurious results. 1

• Regional wall motion abnormalities are always pathological and should mandate further investigation with stress testing or coronary angiography. 1

Referral Indications

• Refer to cardiology if:

  • GLS continues to worsen on serial monitoring (decline >2% from baseline) 5
  • Patient develops symptoms of heart failure (dyspnea, orthopnea, edema) 6
  • Elevated cardiac biomarkers or evidence of active myocardial injury 1
  • Uncertainty about etiology or need for advanced imaging 1
  • Difficulty initiating or titrating guideline-directed medical therapy 7

• Cardiology will assess for specific conditions that present with reduced GLS and normal EF, including heart failure with preserved ejection fraction (HFpEF), hypertrophic cardiomyopathy, infiltrative cardiomyopathies, and restrictive cardiomyopathy. 6