Primary and Secondary prevention of MI; Mitral insufficiency

Question 1

What is considered Primary prevention and Secondary prevention of MI?

Answer 1

Primary prevention is the therapies used to prevent the first event of Cardiovascular disease appearance by lifestyle modications, developing and maintaining healthy habits and following medication regimes in patients at high risk of CVD but have no history of CVD

Secondary prevention is the therapies used to prevent another Cardivascular disease event from occuring, after one event has already occured. It involves Directed drug therapies, Rehabilitation, Lifestyle modifications, Management of comorbidities and maintaining Healthy habits

Question 2

Calculators, Lifestyle, Drugs, Aspirin

What are included in Primary Prevention of MI?

Answer 2

Calculation of ASCVD risk:
- Traditional risk factors [smoking history, family history of CAD, Diabetes test, HTN, Lipid levels]
- ASCVD risk calculators [PCE ASCVD risk, SCORE2, SCORE2-OP, Reynolds risk score, MESA] which gives 10-year ASCVD risk in percentage
- CAC score

All of the risk calculation is used to guide treatment plans, especially for high risk patients [i.e. > 20% 10-year ASCVD risk]

Lifestyle Modifications:
- Smoking cessation [single greatest direct affect on ASCVD risk]
- Diet modifications [suited for heart, like Mediterranian, Mono and polyunsaturated fats, Limit sodium intake, Reduce dietary cholesterol intake, Minimal refined and processed foods]
- Physical activity
- Sleep hygiene [regular 6-8 hours]

Pharmacological therapy:
- Medium-Intensity Statins [20-39 years old with high LDL levels, DM and family history; 40 and older with Intermediate and Borderline 10-year risks]
- High-Intensity Statins [40 and older with high 10-year risk]

Preventive Aspirin:
- Low-dose Aspirin for 40 years and older adults with > 10% 10-year ASCVD risk [not routinely as bleeding risk develops]

Question 3

What are included in Secondary prevention of MI?

Answer 3

Approach:
- Slowing down progression of Atherosclerosis
- Stabilization of existing plaques
- Possible regression of plaques

Drug therapies utilized:
- Low-dose Aspirin [Lifelong single or dual therapy of Aspirin and Clopidogrel]
- Beta Blockers
- ACE inhibitors
- Moderate or High intensity Statins
- Management of Diabetes
- Management of HTN

Lifestyle modifications are also part of secondary prevention [same as in primary prevention]

Question 4

Underlying cause Etiology, Onset Etiology

Etiology of Mitral Regurgitation

Answer 4

Primary Mitral Regurgitation [Organic]: Affects the leaflets or Chorda tendinae directly
- Infective Endocarditis
- Rheumatic Fever
- Degenerative MV diseases [MV prolapse, Mitral annular calcifications, ruptured Chorda tendinae]
- Ischemic MR [Papillary muscle rupture following MI]

Secondary Mitral Regurgitation [Functional]: LV disease process that forces changes in MV function
- Coronary Artery Diseases or MI involving Papillary muscle [rupture or impaired motion]
- Dilated Cardiomyopathies
- Left-sided HF

Acute Mitral Regurgitation: Acute decompensated dysfunction causing Volume overload in LV and LA causing acute HF symptoms

Chronic Mitral Regurgitation: Cardiac remodelling to compensate high EDV and maintain SV [overtime LVEF reduction and HF can occur if progression not stopped]

Question 5

Acute, Chronic compensated and decompensated

Pathophysiology of Mitral Regurgitation

Answer 5

Acute MR:
- MV dysfunction
- Increased LA volume
- Increased LVED volume and Preload
- Rapid increased in LV and LA pressures
- Pulmonary venous congestion [Postcapillary]
- Left heart failure signs

Chronic Compensated MR:
- Eccentric Hypertrophy of LV [cardiac remodelling]
- Increase in volume capacity, Afterload and Preload remain normal
- Normal EF
- Possibly development of Pulmonary HTN

Chronic Decompensated MR:
- Progressive LV enlargement and dysfunction of myocardium [cardiac remodelling]
- Decrease SV, Increase LVEDV
- Increase LA volume
- Increased LV and LA pressures
- Pulmonary congestion, Pulmonary Edema, Pulmonary HTN, Right Heart strain

Question 6

AHA and Carpentier classifications

Classification of Mitral Regurgitation

Answer 6

AHA classification: based on Echo findings of valve anatomy, LVEF, LVESD and other hemodynamic findings
- Stage A: at risk of MR
- Stage B: Moderate MR
- Stage C1: Severe, Asymptomatic MR [LVEF > 60% | LVESD < 40 mm]
- Stage C2: Severe, Asymptomatic MR {LVEF < 60% | LVESD > 40 mm]
- Stage D: Severe, Symptomatic MR

Carpentier Classification: uses Echo to find valve leaflet anatomy and motions, mainly to guide surgical repair planning
- Stage I: Normal leaflet motion
- Stage II: Prolapse or Flailing of leaflets
- Stage IIIA: Leaflet restrictions in both Systole and Diastole
- Stage IIIB: Leaflet restrictions in Systole only

Question 7

Acute and Chronic

Clinical Features of Mitral Regurgitation

Answer 7

Acute Mitral Regurgitation:
- Dyspnea
- Left heart failure signs
- Pulmonary edema [Bibasilar, late inspiration rales and crackling]
- Cardiogenic shock [Tachycardia, Tachypnea, Hypotension, Poor perfusion]
- Palpitation and new onset Atrial Fibrillations
- Soft, Decrescendo Systolic murmur best heard at apex
- Potential S3 sound
- No murmur in severe LV systolic dysfunction or hypotension

Chronic Mitral Regurgitation:
- Exertional Dyspnea, Dry cough
- Fatigue
- Palpitation [several bouts of A.fib or persistent A.fib]
- Fatigue
- Symptoms of Left heart failure and potentially symptoms of Right heart failure
- Lateral displacement of apical pulse
- S3 heart sound
- Quiet S1 sound
- Holosystolic, high pitches murmur [radiates to axilla, best heart at apex | Intensity increased by Preload and Afterload increase]

Question 8

Diagnosis of Mitral Regurgitation

Answer 8

• ECG [Acute - new onset A.fib, Acute ischemic signs | Chronic - LV hypertrophy, P mitrale, A.fib, Signs of right heart strain later in disease]
• CXR [Ddx and to find Pulmonary edema, LA and LV enlargements]
• Echocardiography [TTE for both assessment and classification; TEE if TTE is inconclusive and prior to surgery]
• Labs studies [Troponin, BNP, Blood cultures for IE]
• Additional studies [Cardiac MR if TTE and TEE inconclusive | Stress Echo for Stage A, B | CT angiograph in suspected ischemic cardiomyopathy | Coronary Angiography for ischemic MR and prior to surgical intervention]

Question 9

Treatment Strategies for Acute Mitral Regurgitation

Answer 9

Acute MR is an emergency and immediate management is critical to prevent mortality

Initial Stabilization:
- Management of Acute Heart Failure [Vasodilators - Nitroprusside, Nitrates | Diuretics - Furosemide | NIPPV for Pulmonary edema]
- Management of Cardiogenic Shock [Vasopressors - Norepi | Inotropes - Dobutamine]
- Management of Atrial Fibrillation [Rhythmic control]

Bridging devices: indicated for unstable patients for surgery and no effect of medical therapy for symptomatic patients
- Intra-aortic Ballon Pump
- Left Ventricular Assist Devices

Surgical Management:
- Valve repair
- Valve replacement
- Revascularization [CABG may be helpful for ischemic MR]

Question 10

Treatment strategies for Chronic Mitral Regurgitation

Answer 10

Medical Management:
- Heart Failure management [Diuretics, ACE inhibitors, Beta Blockers]
- Revascularization for Ischemic MR
- Resynchronization therapy for Atrial Fibrillation

Surgical Management:
- Primary MR: Valve repair [favoured], Valve replacement, Clip device
- Secondary MR: LVAD and Cardiac transplant in severe LV remodelling cases