What does an abnormal left ventricular (LV) strain of -15 indicate and what are its potential causes?

Abnormal LV Strain of -15: Clinical Significance and Causes

An LV global longitudinal strain (GLS) of -15% indicates subclinical myocardial dysfunction that represents early cardiac damage preceding overt heart failure, requiring immediate investigation for underlying causes and consideration of therapeutic intervention even if ejection fraction appears normal. 1

Understanding the Strain Value

• Normal LV GLS ranges from -18% to -22%, with values between -16% to -18% considered borderline, and anything above -16% (less negative, such as -15%) classified as abnormal 1, 2
• Strain is expressed as a negative percentage, where values closer to zero (less negative) represent worse myocardial function 1
• GLS is more sensitive than ejection fraction for detecting early myocardial dysfunction, often identifying abnormalities months before EF declines 1
• Strain measurements are abnormal in many clinical settings with preserved LV EF, making this a marker of subclinical dysfunction 3, 1

Primary Causes of Reduced LV Strain (-15%)

Hypertensive Heart Disease

• Chronic hypertension leads to left ventricular hypertrophy (mass index >95 g/m² in women, >115 g/m² in men), which progresses to systolic dysfunction 4
• Structural and functional abnormalities can be detected in hypertensive patients with LVH even before abnormal LV filling develops 5
• Age, LV mass index, and structural myocardial changes are independent determinants of LV dysfunction in hypertensive LVH 5

Ischemic Cardiomyopathy

• Myocardial scar and peri-infarct zones are strong independent predictors of ventricular dysfunction, even after adjusting for LVEF 3
• Post-revascularization patients can develop LV dysfunction with reduced strain despite successful PTCA 6
• Extent of myocardial scar is associated with increased mortality and adverse outcomes 3

Cardiomyopathies

• Hypertrophic cardiomyopathy (HCM) demonstrates abnormal strain even in preclinical stages (sarcomere mutation carriers without LV hypertrophy) 7
• Dilated cardiomyopathy, peripartum cardiomyopathy, and muscular dystrophies present with reduced GLS and mid-myocardial or subepicardial fibrosis patterns 3
• Non-compaction cardiomyopathy shows reduced strain with characteristic trabecular patterns 3

Infiltrative and Inflammatory Conditions

• Myocarditis and inflammatory conditions (including post-viral syndromes like MIS-C) cause reduced strain with myocardial edema 3, 8
• Cardiotoxicity from chemotherapy (anthracyclines) produces reduced strain before EF decline 3

Immediate Diagnostic Workup

Repeat and Confirm Strain Measurement

• Repeat echocardiography with the same equipment vendor within 2-3 weeks, as significant vendor variability exists between different ultrasound machines 1
• Document the absolute GLS value and compare to normal range (normal: -18% to -22%) 1
• Measure LVEF using 3D echocardiography when available for superior reproducibility 1

Comprehensive Echocardiographic Assessment

• Assess diastolic function using four key variables: septal e′ velocity (<7 cm/sec abnormal), lateral e′ velocity (<10 cm/sec abnormal), average E/e′ ratio (>14 abnormal), and LA maximum volume index 3, 1
• Evaluate right ventricular function to exclude biventricular involvement, as this has prognostic implications 1
• Measure LV mass index to identify hypertrophy 4

Advanced Imaging

• Cardiac MRI is indicated when diagnostic uncertainty exists regarding etiology, particularly for suspected infiltrative disease where MRI provides superior tissue characterization 1
• MRI with late gadolinium enhancement differentiates ischemic from non-ischemic cardiomyopathy and identifies specific patterns of infiltration 1
• MRI can detect myocardial scar, edema, and fibrosis patterns that guide diagnosis 3

Laboratory Screening

• Screen for reversible causes: thyroid function, iron studies, nutritional deficiencies (thiamine, selenium) 1
• Measure NT-proBNP levels as elevated values correlate with worse outcomes 7

Management Approach

Initiate Guideline-Directed Medical Therapy

• Start ACE inhibitors/ARBs and beta-blockers even with preserved ejection fraction when GLS is reduced 1, 6
• Consider SGLT2 inhibitors for heart failure with reduced ejection fraction 6
• Add mineralocorticoid receptor antagonists if indicated for ischemic cardiomyopathy 6

Address Modifiable Risk Factors

• Aggressive hypertension control with target blood pressure optimization 4, 1
• Diabetes management, smoking cessation, alcohol abstinence 1, 6
• High-intensity statin therapy for secondary prevention if CAD is present 6

Consider Stress Testing

• Stress echocardiography should be considered to assess for residual ischemia, evaluate contractile reserve and viability of hypokinetic segments 6
• Coronary angiography may be warranted if stress testing reveals significant inducible ischemia 6

Critical Pitfalls to Avoid

• Do not dismiss borderline GLS values (between -16% to -18%) as normal—these represent early dysfunction requiring close monitoring 1
• Never administer vasodilators or diuretics aggressively without ruling out dynamic LVOT obstruction in patients with hypertension and reduced strain, as this can worsen obstruction and cause severe hypotension 4
• GLS values are not applicable to patients currently receiving inotropic agents or mechanical circulatory support, as these interventions alter the measurement 1
• Diastolic abnormalities often precede systolic dysfunction and cause symptoms despite normal EF—always perform comprehensive diastolic assessment 1
• Reduction in GLS over time is more concerning than a single abnormal value and mandates therapeutic intervention 1

Prognostic Implications

• Abnormal LV strain with a cutoff of >-13.8% (less negative than -13.8%) is associated with significantly higher risk of death in acute cardiac conditions 9
• Despite normal LVEF, abnormal LV GLS predicts worse outcomes and represents a critical window for intervention to prevent progression to symptomatic disease 1, 9
• Persistent abnormal systolic strain after initial treatment indicates ongoing myocardial dysfunction requiring continued monitoring 8

Follow-Up Strategy

• Regular follow-up echocardiography to assess response to medical therapy, potential improvement in LVEF and strain, and development of complications 6
• Titrate medications to optimal doses and monitor for symptoms of heart failure or recurrent angina 6
• Evaluate for ICD if LVEF remains ≤35% despite 3 months of optimal medical therapy 6