Introduction

With advances in cancer therapy, particularly the use of anthracyclines (e.g., doxorubicin) and targeted agents (e.g., trastuzumab), survival rates have improved substantially. However, these benefits come with increased risks of long-term cardiovascular complications. The prevalence of chemotherapy-induced cardiotoxicity ranges from 5% to 48% depending on cumulative dose, age, baseline cardiovascular status, and concurrent therapies.

Despite pharmacological prophylaxis and surveillance, many patients experience reduced cardiac reserve, fatigue, exercise intolerance, and dyspnea during or after treatment. Physiotherapy plays a crucial, yet underutilized, role in early detection, functional restoration, and long-term management of CIC. Early intervention not only improves quality of life but may also enhance adherence to cancer treatment and reduce hospital readmissions.

Pathophysiology of Chemotherapy-Induced Cardiotoxicity

Chemotherapy drugs disrupt cardiac function through several mechanisms:

• Oxidative stress and mitochondrial damage (particularly by anthracyclines)

• Impaired myocyte regeneration

• Inhibition of HER2 pathways essential for cardiac cell survival

• Endothelial dysfunction and inflammation

• Cumulative and dose-dependent myocardial apoptosis

These mechanisms lead to progressive left ventricular dysfunction, diastolic stiffness, decreased stroke volume, and reduced aerobic capacity. Subclinical damage may precede echocardiographic changes or symptom onset by weeks to months.

Role of Physiotherapy in CIC Management

Objectives of Physiotherapy

• Preserve or improve cardiorespiratory fitness

• Prevent deconditioning and muscle wasting

• Reduce fatigue and dyspnea

• Improve quality of life and emotional well-being

• Promote safe return to activities of daily living (ADLs)

• Support long-term cardiovascular health

Assessment Before Initiating Therapy

Before prescribing exercise interventions, physiotherapists must conduct a thorough evaluation, including:

• Cardiopulmonary status (resting HR, BP, ECG findings, LVEF via echocardiogram)

• Functional capacity (6-minute walk test, CPET)

• Cancer fatigue scales (e.g., FACIT-Fatigue)

• Psychosocial screening

• Risk stratification (low vs. moderate vs. high cardiac risk)

Multidisciplinary collaboration with cardiologists and oncologists is essential, particularly in patients with active or advanced heart failure.

Physiotherapy Interventions

1. Aerobic Conditioning

Core Concept:
Aerobic training aims to counteract deconditioning, preserve cardiac output, and improve peripheral oxygen utilization. CIC often leads to reduced stroke volume, poor chronotropic response, and skeletal muscle atrophy all of which contribute to exercise intolerance.

Clinical Approach:

• Begin with low-intensity, monitored activities such as walking, stationary cycling, or arm ergometry.

• Assess baseline cardiopulmonary tolerance via 6-minute walk test or Borg RPE to determine starting point.

• Monitor hemodynamic responses and perceived exertion closely in each session. Heart rate alone can be misleading in CIC due to β-blocker therapy or autonomic dysfunction.

Modifications:

• For patients with postural hypotension or poor endurance, interval training with frequent rest breaks is preferred.

• For those on active chemotherapy cycles, shorter bouts of movement throughout the day may be safer and better tolerated than structured sessions.

Cautions:

• Defer training if there's active myocarditis, new onset arrhythmias, or symptomatic hypotension.

• Modify or hold exercise during nadir periods (7–10 days post-chemo) when patients are immunocompromised.

2. Resistance Training

Core Concept:
Loss of muscle mass and strength (sarcopenia) occurs rapidly during cancer therapy, especially in the presence of fatigue and inflammation. Resistance training helps preserve lean mass and supports cardiac efficiency by offloading peripheral demand.

Clinical Approach:

• Emphasize multi-joint functional movements (e.g., sit-to-stand, step-ups, wall push-ups) rather than isolated muscle training.

• Start with body weight or light resistance bands, progressing based on symptom tolerance.

• Focus on slow, controlled movements, particularly during eccentric phases, which are less metabolically demanding.

Tailoring Strategies:

• For patients with bone metastasis, modify exercises to avoid loading affected sites.

• For lymphedema risk (e.g., post-mastectomy), use graded resistance and compression garments if necessary.

Integration Tip: Combine resistance and aerobic components in circuit formats to enhance both cardiovascular and muscular adaptations while reducing boredom.

3. Respiratory Physiotherapy

Core Concept:
Many CIC patients develop dyspnea disproportionate to effort not purely from cardiac insufficiency but due to respiratory muscle weakness, poor thoracic mobility, and fatigue. Respiratory physiotherapy addresses this multidimensional limitation.

Clinical Approach:

• Breathing retraining: Teach diaphragmatic and pursed-lip breathing to reduce accessory muscle use and promote efficient ventilation.

• Thoracic mobility exercises: Mobilize costovertebral joints and intercostals through side stretches, thoracic rotations, and rib expansion drills.

• Respiratory muscle strengthening: Incorporate incentive spirometry, inspiratory resistance training, or breath-hold control if tolerated.

Monitoring and Feedback:

• Use dyspnea scales (e.g., modified Borg, MRC) before and after sessions.

• Teach patients to recognize warning signs of decompensation (e.g., orthopnea, paroxysmal nocturnal dyspnea).

4. Fatigue Management and Energy Conservation

Core Concept:
Cancer-related fatigue is persistent, not relieved by rest, and worsened by inactivity. It has physiological, emotional, and neurological components, often worsened by cardiotoxicity.

Clinical Approach:

• Use activity pacing prioritize and schedule high-demand tasks during energy “peaks.”

• Teach body mechanics for daily tasks (e.g., reducing arm elevation, using assistive devices).

• Integrate fatigue journaling to help patients track energy fluctuations and triggers.

• Encourage active rest, such as gentle stretching or guided breathing, instead of passive inactivity.

Clinical Insight:
Overexertion in the early stages can worsen fatigue. But so can underactivity. The key is just enough activity to challenge without overwhelming a delicate, evolving balance.

5. Autonomic Regulation and Relaxation Training

Core Concept:
Chemotherapy and cardiac dysfunction often disrupt autonomic balance, leading to resting tachycardia, poor heart rate variability, and increased sympathetic tone. This contributes to anxiety, sleep dysfunction, and impaired recovery.

Clinical Approach:

• Integrate mind-body practices like mindfulness, guided imagery, or gentle yoga.

• Use vagal tone enhancement techniques: prolonged exhalation, humming, or cold facial stimulation.

• Teach progressive muscle relaxation and biofeedback (if available).

Relevance to CIC:
These techniques help reduce stress-mediated vasoconstriction, improve cardiac recovery after effort, and support long-term cardiovascular adaptability.

6. Education and Empowerment

Core Concept:
Knowledge is therapy. CIC patients often face fear, uncertainty, and a sense of fragility. Empowering them with accurate, tailored information can improve adherence and outcomes.

Education Focus:

• What cardiotoxicity means and how movement affects recovery

• The role of physiotherapy in improving prognosis

• Early signs of cardiac decompensation (e.g., swelling, weight gain, SOB)

• Safe self-monitoring strategies (daily HR, fatigue logs, symptom checklists)

Delivery Modes:

• One-on-one sessions, written handouts, or digital platforms (especially for younger or tech-savvy patients)

• Include caregivers when possible to support reinforcement and reduce overprotection

7. Multidisciplinary Coordination

Core Concept:
CIC management is not a solo act. Physiotherapy should be part of a cardio-oncology pathway with shared goals across oncology, cardiology, and rehabilitation.

Collaboration Opportunities:

• Align therapy timing with chemotherapy cycles

• Coordinate with cardiologists for up-to-date ejection fraction data

• Get clearance for activity in borderline cases

• Refer to mental health professionals when anxiety or depression impedes engagement

8. Long-Term Follow-Up and Transition

Core Concept:
Cardiotoxic effects can manifest or worsen months after chemotherapy ends. Physiotherapy’s role extends beyond acute care into survivorship.

Long-Term Considerations:

• Develop home-based maintenance programs

• Teach patients how to self-progress or regress based on symptoms

• Encourage participation in community cardiac rehab or cancer survivorship programs

• Reassess every 6–12 months for functional, cardiovascular, and psychological changes

Barriers to Implementation

• Limited awareness among oncologists about rehab referral

• Lack of standardized exercise protocols for CIC

• Fear of exacerbating cardiac dysfunction

• Poor reimbursement for physiotherapy services in oncology

• Fatigue, depression, and treatment side effects limiting adherence

Future Directions

• Pre-habilitation before starting chemotherapy to build cardiac reserve

• Wearable tech for remote heart rate and HRV monitoring

• Tele-rehabilitation models in rural or resource-limited settings

• Randomized controlled trials comparing specific physiotherapy modalities

• Development of CIC-specific physiotherapy guidelines under cardiopulmonary rehab societies

Conclusion

Physiotherapy is a powerful, yet underused, intervention in the management of chemotherapy-induced cardiotoxicity. Through carefully tailored aerobic, resistance, and respiratory training, physiotherapists can improve functional outcomes, reduce complications, and enhance quality of life in this vulnerable population. With growing recognition of the need for integrated cancer care, the role of physiotherapists in onco-cardiology should be institutionalized, standardized, and supported through policy and training.