18.1 Disease Mechanism: The Pathophysiology of CVD
Atherosclerosis is the foundational process underlying most CVD and ischemic stroke. It involves:
- Endothelial dysfunction (damage to blood vessel inner lining) — triggered by hypertension, smoking, hyperglycemia, oxidized LDL cholesterol, and inflammation
- Oxidized LDL particles infiltrate the arterial wall → macrophages engulf them → form "foam cells" → fatty streaks develop
- Over decades, plaques grow, calcify, and narrow the arterial lumen
- Plaque rupture triggers clot formation (thrombosis) → blocks coronary artery (myocardial infarction) or cerebral artery (ischemic stroke)
Primary modifiable risk factors:
| Risk factor | Dietary intervention | Exercise intervention |
|---|---|---|
| Hypertension | DASH diet, sodium reduction, potassium increase | Aerobic exercise (−5–8 mmHg systolic) |
| Elevated LDL cholesterol | Soluble fiber, plant sterols, reduced saturated/trans fat | Moderate-intensity aerobic exercise |
| Low HDL cholesterol | Monounsaturated fats, omega-3, moderate alcohol (optional) | High-intensity exercise most effective |
| High triglycerides | Reduced refined carbohydrates and alcohol, omega-3 | Aerobic exercise; significant effect |
| Inflammation (hs-CRP) | Mediterranean diet, omega-3, polyphenols | Exercise reduces hs-CRP independently |
| Obesity / visceral fat | Caloric deficit; dietary pattern quality | Combination of resistance + aerobic |
| Insulin resistance | Low-GI diet, Mediterranean pattern | Resistance training, walking |
Key biomarkers to monitor:
| Biomarker | Optimal target |
|---|---|
| LDL cholesterol | < 100 mg/dL (< 70 in high-risk individuals) |
| HDL cholesterol | > 60 mg/dL (men > 40, women > 50 minimum) |
| Triglycerides | < 100 mg/dL (< 150 acceptable) |
| hs-CRP | < 1.0 mg/L (< 3.0 acceptable) |
| Blood pressure | < 120/80 mmHg |
| ApoB | < 80 mg/dL (superior CVD risk marker vs. LDL alone) |
| Lipoprotein(a) | < 30 mg/dL (genetic; minimally diet-responsive) |
18.2 Dietary Protocol for Cardiovascular Health
The Mediterranean Diet: Tier-1 Evidence
The Mediterranean dietary pattern has the strongest and most consistent evidence base for CVD prevention of any dietary approach. The PREDIMED trial demonstrated a 30% reduction in major cardiovascular events compared to a low-fat control diet.
Cardioprotective mechanisms:
- High polyphenol intake (olive oil, red wine, vegetables, berries) → reduces LDL oxidation and endothelial inflammation
- Omega-3 fatty acids (fatty fish, walnuts, flaxseed) → reduces triglycerides, lowers arrhythmia risk, decreases platelet aggregation
- High soluble fiber (legumes, oats, vegetables) → reduces LDL-C via bile acid sequestration
- Monounsaturated fats (olive oil, avocado) → improve LDL particle size (larger, less atherogenic particles)
- Moderate alcohol (red wine with meals, for those who drink) → raises HDL-C; polyphenols provide additional benefit
The DASH Diet: Blood Pressure Specificity
Dietary Approaches to Stop Hypertension (DASH) is specifically designed to lower blood pressure. Consistent DASH adherence reduces systolic blood pressure by 8–14 mmHg — comparable to a single antihypertensive medication.
DASH principles:
- Sodium: < 1,500–2,300 mg/day (the lower the better for hypertension)
- Potassium: 4,700 mg/day (counteracts sodium's pressure-raising effect); from bananas, sweet potatoes, legumes, leafy greens
- Calcium: 1,250 mg/day from low-fat dairy or fortified plant alternatives
- Magnesium: 500 mg/day — directly involved in vascular smooth muscle relaxation
- Limit alcohol: > 2 drinks/day meaningfully raises blood pressure
Specific Cardioprotective Foods
| Food | CVD benefit | Mechanism |
|---|---|---|
| Extra virgin olive oil (≥4 tbsp/day) | 30% reduction in CV events (PREDIMED) | Oleocanthal (anti-inflammatory), oleic acid, polyphenols |
| Fatty fish (2–3×/week) | ~36% reduction in CV mortality | EPA/DHA: anti-arrhythmic, anti-inflammatory, triglyceride reduction |
| Walnuts (30g/day) | Improved endothelial function | ALA omega-3, polyphenols, arginine (NO precursor) |
| Oats / barley | −5–10% LDL reduction | Beta-glucan soluble fiber; bile acid sequestration |
| Blueberries | Reduced arterial stiffness | Anthocyanins improve endothelial function |
| Dark chocolate (≥85%, 20–30g/day) | −3–4 mmHg systolic; improved vasodilation | Flavanols stimulate nitric oxide production |
| Garlic | Modest BP and LDL reduction | Allicin; hydrogen sulfide production |
| Green tea | Reduced atherosclerosis progression | EGCG catechins; LDL oxidation inhibition |
| Tomatoes / lycopene | Reduced LDL oxidation | Lycopene — most bioavailable in cooked tomatoes with fat |
Foods That Accelerate CVD Risk
- Trans fats (partially hydrogenated oils): Most atherogenic dietary component; raise LDL and lower HDL simultaneously. Banned in many countries but still present in some processed foods
- Sodium in excess: Primary dietary driver of hypertension — major independent CVD risk factor
- Refined carbohydrates and added sugars: Drive triglycerides, reduce HDL, promote insulin resistance and visceral fat
- Processed meat (bacon, salami, sausage): Associated with CVD independent of saturated fat — possibly via nitrosamines, sodium, and heme iron oxidative stress
- Excessive alcohol: > 2 drinks/day raises blood pressure, promotes arrhythmia (especially atrial fibrillation), and contributes to cardiomyopathy
18.3 Exercise Protocol for Cardiovascular Health
Exercise is, pound for pound, the most effective cardiovascular protective intervention available. A meta-analysis in The Lancet (2016) found that 150 minutes/week of moderate exercise reduced cardiovascular mortality by 35% — comparable to statin medication in primary prevention.
Aerobic Exercise: The Foundation
- Frequency: 5×/week (or minimum 150 min/week moderate / 75 min/week vigorous)
- Intensity: 50–85% of maximum heart rate; ideally a mix across the intensity spectrum
- Types: Walking, jogging, cycling, swimming, rowing — any sustained rhythmic activity
- Primary adaptations:
- Reduces resting heart rate (cardiac efficiency)
- Lowers blood pressure (vasodilation and reduced peripheral resistance)
- Improves HDL-C and reduces triglycerides
- Reduces systemic inflammation (hs-CRP)
- Enhances endothelial function and arterial compliance
- Promotes collateral vessel development (cardiovascular redundancy)
Resistance Training: Underrated for Heart Health
The AHA (2019 guidelines) now formally recommends resistance training ≥2×/week for cardiovascular risk reduction. Benefits include:
- Modest blood pressure reduction (−2–4 mmHg)
- Improved insulin sensitivity (major CVD risk factor)
- Favourable body composition (reduced visceral fat)
- Prevention of sarcopenia — itself a CVD risk factor in aging
Protocol: 2–3×/week; major compound movements; moderate load (12–15 reps); circuit-style training (reduced rest) has greater cardiovascular benefit than traditional resistance protocols
Zone 2 Training: The Cardiovascular Sweet Spot
Zone 2 (60–70% of max HR; can hold a full conversation) is the intensity at which mitochondrial biogenesis and fat oxidation are maximized. In the cardiovascular context, sustained Zone 2 work:
- Develops the aerobic base that protects against sudden cardiac events
- Trains the heart's left ventricle to handle greater stroke volumes (cardiac output)
- Is the intensity at which arterial compliance (vessel elasticity) most improves
Zone 2 target: 3–4 hours/week in sedentary adults rebuilding cardiovascular health; achievable via walking, cycling, swimming.
Cardiac Rehabilitation: The Clinical Standard
For individuals who have experienced a myocardial infarction, heart failure, or cardiac surgery, structured cardiac rehabilitation (supervised exercise + education) reduces CV mortality by 25–30% and all-cause mortality by 15–20%. It is the most evidence-backed intervention in secondary CVD prevention.
Phases:
- Phase 1: In-hospital mobilization (days 1–3 post-event)
- Phase 2: Supervised outpatient program (weeks 2–12)
- Phase 3: Community-based maintenance
Any exercise program post-cardiac event should begin under medical clearance and ideally within a structured rehabilitation framework.
Stroke-Specific Exercise Considerations
Post-ischemic stroke, exercise serves both secondary prevention (reducing recurrence risk) and neurological rehabilitation (promoting neuroplasticity).
- Aerobic exercise improves cerebral blood flow and promotes BDNF (brain-derived neurotrophic factor), supporting neural repair
- Balance and coordination training reduces fall risk (major concern post-stroke)
- Resistance training rebuilds strength in affected limbs (particularly hemiparetic patients)
- Start intensity conservatively — begin at 40–50% max HR and progress based on tolerance and physician guidance