Ischemic Heart Disease, etc. Dr. Unrein lecture Flashcards
Ischemic heart disease physiology
Coronary blood demand exceeds coronary blood flow
Decreased supply vs. Increased demand
Myocardial metabolism is aerobic!
IHD Etiologies (supply versus demand)
Atherosclerosis Hyperthyroidism Anemia Emotional stress Variant angina Prinzmetal’s - vasospasm in etiology, associated with other vasospastic phenomena
IHD Physical presentation
Retrosternal, aching or squeezing, may radiate to neck, shoulder (usually left), back, teeth, epigastrium
Ischemic equivalents/Associated symptoms
Shortness of breath Diaphoresis Nausea and/or vomiting Dizziness Weakness
IHD risk factors
Increasing age Male Smoking - Dose-response relationship - 2-3 fold increase risk of dying form cardiovascular disease - Rapid risk reduction in 2 years after quitting Hypertension Diabetes High cholesterol/Dyslipidemia – the most powerful modifiable risk factor Family history - Premature heart disease in a first-degree relative ---- Male under 45 ---- Female under 55 Cocaine use Methamphetamine use Physical inactivity
METABOLIC SYNDROME
IHD Conditional risk factors
lack validation and/or used to supplement clinical judgment
Homocysteine (an intermediate amino acid in methionine metabolism)
- Cardiac risk not improved with folate supplementation
Lipoprotein(a)
- Resembles LDL with an added glycoprotein
- Few pharmacological agents lower Lipoprotein(a) [Niacin can reduce levels]
- No research has demonstrated efficacy in CV risk reduction by lowering Lipoprotein(a)
hsCRP - (High-sensitivity C- reactive protein)
- Useful in assessing patients with intermediate Framingham risk scores, reclassifies up to 30% into either low or high risk
LDL particle size
Inconclusive and needs further study
Antioxidant therapies (vitamins E &C and beta-carotene)
Omega-3-fatty acids intake has been shown to reduce cardiovascular risk but direct study of supplementation is not well-defined
Cardiovascular Inflammation Reduction Trial (CIRT)
CIRT is an NHLBI-funded randomized double-blind placebo-controlled trial designed to:
directly test the inflammatory hypothesis of atherothrombosis
determine whether the common anti-inflammatory drug low-dose methotrexate (LDM, target dose of 15 to 20 mg po weekly) will reduce rates of recurrent myocardial infarction, stroke, or cardiovascular death among patients with established coronary artery disease and either type 2 diabetes or metabolic syndrome
determine whether LDM will reduce the rate of new onset type 2 diabetes among those with metabolic syndrome at study entry
Framingham risk
Low risk less than 10% 10-year Framingham risk
- Monitor
Intermediate risk 10-20% 10-year Framingham risk
- Further evaluation
High risk >20% 10-year Framingham risk
– Aggressive risk modification
Framingham risk score
Reynolds Risk Score
- Sex specific tool that accounts for family history and high sensitivity C-reactive protein
Reduction of risk factors
Aspirin Risk vs. benefit Reduction of blood pressure Reduction of hyperlipidemia Smoking cessation Regular exercise Weight reduction and reduction of BMI (
IHD diagnostic testing
Serum bio-makers - CPK – MM, MB, BB - Troponin - LDH (1-5) Exercise stress test Pharmacological stress test Imaging augmentation Angiography CT determined coronary artery calcium score - Maybe useful for patient with an intermediate risk for CAD
Stress Test
Patients need to be stable as these are provocative tests.
Exercise
Bruce protocol
HRmax = 220 − age
Pharmacological
- Dobutamine: Increase cardiac stress and oxygen demand
- Adenosine/Dipyridamole: Vasodilation
IHD imaging
Imaging
- Nuclear
- Echocardiograph
Angiography
- Lower dose radiation
- Gold standard for defining coronary occlusion
CT/MRI
- Good to estimate coronary artery calcium scoring and anatomy, but no functional information
Acute Coronary Syndromes
A spectrum of a single disease
Unstable Angina Non-ST-elevation MI ST-elevation MI
Stratified based upon ECG and serum biomarkers (troponin and creatine kinase – CPK)
Typical chest pain clinical presentation
(Central, Visceral, Exertional)
1) Central substernal pain/discomfort – usually retrosternal
May radiate to the shoulder, arms, jaw or back
Visceral – usually poorly located; associated with nausea, vomiting, diaphoresis and/or shortness of breath
2) Exertional – Brought on or increased with activity/emotional stress
25% maybe silent ischemia
25% atypical
Woman, diabetics, elderly
3) Relieved by nitrates or rest
Chest Pain Evaluation
Low probability – no further work up
Intermediate probability EKG Normal – stress test
Intermediate probability, EKG Abnormal – stress test with possible imaging augmentation, treatment based upon findings
High probability – medical therapy and coronary angiography, treatment based upon findings
Unstable angina and Non-ST-elevation myocardial infarction
Similar on ECG, differentiated by biochemical marker of injury and changes the death risk stratification
Risk stratification based upon the TIMI trial risk scores (conservative approach may be attempted with 2 or fewer indicators)
Age ≥ 65 ≥ 3 traditional cardiac risk factors Documented CAD with a ≥ 50% stenosis ST segment abnormalities ≥ 2 two anginal episode in the last 24h hours Used aspirin in the last week Elevated cardiac enzymes
Unstable angina and Non-ST-elevation myocardial infarction
Risk score
0-2 low risk – medical therapy and stress test to evaluate therapy, if stress test abnormal - angiography
3-4 intermediate risk – medical therapy and early angiography
5-7 high risk – medical therapy and early angiography
Acute Coronary Syndromes History and Physical Exam
Necessary to distinguish between syndromes that mimic acute coronary syndromes or may change the disease management
Onset – timing of treatment
Risk factor evaluation
Recent medication use (aspirin etc)
Aortic dissection – in the back, often described as a tearing sensation (Type A dissection may extend into the right coronary artery and the presentation may be that of an actual inferior wall MI with the dissection, although the left coronary artery can be involved but less often) – Widened mediastinum on chest X-Ray
Pericarditis – recent viral illness, pleuritic chest pain, pulses paradoxus
Pulmonary embolism – inactivity, malignancy/hypercoagulable state, pleuritic chest pain – **New onset of Atrial fibrillation
CHF – SOB, orthopnea*
ST-elevation myocardial infarction
Early reperfusion indicated – time is muscle!
- Thrombolytic therapy versus rapid revascularization in the catheterization lab
- —- Most significant determining factor is “Door to Balloon” time (less than 90 minutes)
- — Absolute contraindications to thrombolytic therapy: Intracranial Hemorrhage, Ischemic CVA in the last 3 months, Facial trauma in the last 3 months, Bleeding diathesis
—-Relative contraindications to thrombolytic therapy: Thrombolytic therapy does not has a clear benefit weighed against the risks beyond 12 hours; Chronic, severe, poorly-controlled hypertension; Severe uncontrolled hypertension on presentation; Ischemic CVA > 3 months, known intracranial pathology; Dementia
Internal bleeding within the last 4 weeks; Noncompressible vascular site; Pregnancy; Peptic Ulcer disease; Current anticoagulant use
Higher death risk cases
– New LBBB, Anterior wall MI, cardiogenic shock, ventricular arrhythmias and advanced age (>75)
Myocardial Infarction Complications - Early
Early complications – immediate or first few hours
Thrombolytics
- Bleeding (2-3 times higher incidence of hemorrhagic CVA in women)
- Reperfusion arrhythmias
IWMI
- Bradycardia and AV block – AV nodal perfusion by the right coronary artery
- Right ventricular infarction, always think about RV infarct with inferior wall MI
- Hypotension for volume depletion
AWMI
- Pump failure and CHF in large area infarcts, cardiogenic shock
- – Intra-aortic balloon pump synchronous counterpulsation
Myocardial Infarction Complications - Late
Later Complications – After the first 24-48 hours
Cardiogenic shock
- Pump function loss and thought to have an inflammatory component
VSD
- New systolic murmur and thrill on left sternal border
Papillary muscle rupture and MR
- New systolic murmur, pulmonary edema, thrill and cardiogenic shock
Free wall rupture
- Electromechanical dissociation
- First infarction, anterior infarctions, females, elderly
Left ventricular thrombus
- Blood stasis, endocardial injury and possible inflammation leading to a hypercoagulable state
- Most often located in the left ventricular apex
Post ACS Mortality Risk Stratification
To determine level of intervention prior to hospital discharge
Angiography vs. Non-invasive testing:
Used to identify high-risk patients - three vessel disease and left main disease require revascularization
Patients should have evaluation of ejection fraction and a provocative ischemic test, if they have been treated medically (medication and/or with angioplasty)
Angiography indications
EF less than 40%
Clinically significant ischemia on non-invasive testing
Arrhythmias during acute hospital stay
Recurrent chest pain during the hospital stay
Significant heart failure during the stay
Post Acute Coronary Syndrome Mortality Intervention
Mortality reduction:
Beta-blockers 20% Aspirin 33% Angiotensin-Converting Enzyme Inhibitors Normal EF 17% Reduced EF 23% HMG-CoA Reductase Inhibitors 25-30% Proportional to the reduction in LDL levels LDL goal
Chronic Coronary Artery Disease Stratification
Diagnostic evaluation:
Pretest probability
- Patients with high pretest probably may be treated empirically and then stressed tested in order to evaluate therapy
Ability to exercise
ECG findings
Co-morbid diseases (pulmonary)
Non-cardiac surgery risk stratification
Assess exercise capacity
Types of tests/ indications
Exercise stress test
Intermediate risk
Assess treatment (stable vs. unstable)
Chemical stress test
Dobutamine, dipyridamole, adenosine
Inability to exercise/physical limitations due to lack of conditioning or co-morbidities
Coronary angiography – the gold standard
Positive stress test
Successfully resuscitated for cardiac arrest
Life limiting angina despite medical therapy
Unclear diagnostic evaluation
ST segment elevation MI – interventional as well as diagnostic
Coronary artery calcium (CT or MRI)
Highly effective in negative predictive value, also used to evaluate patients with an intermediate Framingham score
Females
Average age of diagnosis 10 years later than for males
- Originally thought to be an estrogen protective effect
- Results in more comorbidities and more complicated course of - disease
- Due to alterations in pharmacokinetics of aging/volume of distribution, medications often dosed inappropriately
Have more vasospastic presentation and therefore less obstructive coronary disease
- Lower specificity with higher false positive exercise ECG testing
More non-cardiac chest pain syndromes
More atypical presentations
- Shortness of breath, palpitations, dizziness, and syncope
Hormone replacement
- Has not been shown to reduce CAD risk; has lead to increase venous thromboembolism and CVA
Diabetics
Between two and eight times more likely to suffer from and die from cardiovascular diseases
Patients typically have more advanced and higher grade disease and less collateralization at presentation
Risk reduction
- Glycemic control
- Blood pressure control
Diagnosis
- Often difficult due to autonomic neuropathy
- Fatigue, dyspnea, nausea and vomiting may predominate the presentation
- Silent ischemia
- Exercise stress testing has similar diagnostic value
- Some care with angiography, but not an absolute contraindication – contrast nephropathy
