Sir William Osler said, “Variability is the law of life, and as no two faces are the same, so no two bodies are alike, and no two individuals react alike and behave alike under the abnormal conditions which we know as disease<br />
DEFINITION<br />Criteria for Acute ,Evolving ,Recent MI :<br />Either of the following criteria satisifies the diagnosis:<br />1.Typical rise and /or fall of biochemical markers of myocardial necrosis with atleast one of the following :<br />A.Ischemic symptoms<br />B.Development of the pathological q waves in the ECG.<br />C.Ecg changes indicative of ischemia.(ST segment elevation or depression).<br />D.Imaging evidence of new loss of viable myocardium or new RWMA.<br />2.Pathological findings of an acute myocardial infarction.<br />
EPIDEMIOLOGY<br /><ul><li>Myocardial infarction is a common presentation of Ischemic heart disease.
Worldwide more than 3 million people have STEMIs and 4 million have NSTEMIs a year.
Coronary heart disease is responsible for 1 in 5 deaths in the United States.</li></li></ul><li>EPIDEMIOLOGY-India<br />In India, cardiovascular disease (CVD) is the leading cause of death. 32% of all deaths in 2007 .<br />Relatively new epidemic in India.<br />Mortality estimates due to CVD vary widely by state, ranging from 10% in Meghalaya to 49% in Punjab (percentage of all deaths). Punjab (49%), Goa (42%), <br />Tamil Nadu (36%) and Andhra Pradesh (31%) have the highest CVD related mortality estimates.<br />State-wise differences are correlated with prevalence of specific dietary risk factors in the states. <br />Moderate physical exercise is associated with reduced incidence of CVD in India (those who exercise have less than half the risk of those who don't).<br />
EPIDEMIOLOGY<br /><ul><li>Usually anterior wall MI is more than other segment MI because of conjunction of HTN and diabetes along with the presence of hypercholeosterolemias in C.A.D -----Br heart journal 2000..ncbi.nch.gov/pmc
RVMI is present in one third of patients with IWMI ,but clinically significant in less than 50 % of the one third…. CMDT 2009.
AV block is more common than infranodal block and occurs in approximately 20% of IWMI. (infranodal – AWMI) ………CMDT 2009 .
Sinus bradycardia is more common in IWMI (tahcycardia in AWMI)
Posterior wall MI is assosciated with 5% of IWMI or lateral MI but rarely occurs alone.</li></li></ul><li>ETIOLOGY<br /><ul><li>Atherosclerosis. 90% of MIs result from an acute thrombus that obstructs an atherosclerotic coronary artery. Plaque rupture and erosion - the major triggers for coronary thrombosis.</li></li></ul><li>CAD without atherosclerosis<br /><ul><li>Secondary to vasculitis
Sense of impending doom.</li></li></ul><li><ul><li>occurs most often in the early morning hours, -- increase in catecholamine-induced platelet aggregation and ↑ serum concentrations of plasminogen activator inhibitor-1 (PAI-1) that occur after awakening.
In general, the onset is not directly associated with severe exertion. Instead, it is concomitant with exertion.
The immediate risk of myocardial infarction increases 6-fold on average post MI,CAD and by as much as 30-fold in sedentary people. ncbi.nbl.com
Anginal equivalent --abdominal pain,jaw pain,sharp pain in women,elderly.</li></li></ul><li>High index of suspicion<br /><ul><li>women,
positive family history for early coronary disease ---- any first-degree Male aged≤ 45 years, female relative aged ≤ 55 years who MI </li></li></ul><li>Silent MI<br /><ul><li>Half of myocardial infarctions are clinically silent in that they do not cause the classic symptoms described above and consequently go unrecognized by the patient.
In as many as 25% of elderly patients, a population in whom 50% of myocardial infarctions occur; in such patients, the diagnosis is often established only retrospectively, by applying electrocardiographic criteria or by scanning the patients using 2-dimensional (2D) echocardiography or magnetic resonance imaging (MRI).
On clinical evaluation, ventricular aneurysms may be recognized late, with symptoms and signs of heart failure, recurrent ventricular arrhythmia, or recurrent embolization. </li></li></ul><li>Physical examination<br /><ul><li>Physical examination findings can vary; comfortable in bed, with normal examination results, may be in severe pain, with significant respiratory distress and a need for ventilatory support.
Hypotension may indicate ventricular dysfunction due to ischemia.
Hypotension in the setting of myocardial infarction usually indicates a large infarct secondary to either decreased global cardiac contractility or a right ventricular infarct.</li></li></ul><li>Signs<br /><ul><li>Bradycardia
Hypotension----due to parasympathetic hyperactivity.
Increased respiration – cheynes stokes –anxiety and pain.
On cardiac auscultation--S4 is almost universally present in patients in SR with STEMI.but non specific.
S3 ,S4 heard along the left sternal border and increases on inspiration.—RVMI –RVF</li></li></ul><li>IWMI with RVMI <br /><ul><li>The evidence of right ventricular ischemia should be sought in all patients with acute inferior MI at the time of admission. RT precordial leads, in particular lead V4R must be recorded in all patients with inferior MI. –ACC guidelines
1-mm ST segment elevation in the right precordial lead V4R is the single most predictive ECG finding in patients with right ventricular ischemia This finding, however, may be transient; half of the patients show resolution of ST elevation within 10 hours of the onset of symptoms .</li></li></ul><li>IWMI with RVMI<br /><ul><li>Distention of neck veins is commonly described as a sign of failure of the RV.
Impaired right ventricular diastolic function also leads to systemic venous hypotension, edema, and hepatomegaly with abdominojugular reflux, which may result in saline-response underfilling of the LV and a concomitant reduction in cardiac output.
Peripheral cyanosis, edema, pallor, diminished pulse volume, delayed rise, and delayed capillary refill may indicate vasoconstriction, diminished cardiac output, and right ventricular dysfunction or failure.</li></li></ul><li>Diagnosis<br /><ul><li>ECG
In Inferior myocardial infarction, record a right-sided ECG to rule out right ventricular infarct.
Daily serial ECGs for the first 2-3 days and additionally as needed. </li></li></ul><li><ul><li>High probability of myocardial infarction is indicated either by ST-segment elevation greater than 1 mm in 2 anatomically contiguous leads ,2mm in chest leads or by the presence of new Q waves.
intermediate probability of myocardial infarction are ST-segment depression, T-wave inversion, and other nonspecific ST-T wave abnormalities.
low probability of myocardial infarction are normal findings on ECGs
however, normal or nonspecific findings on ECGs do not exclude the possibility of myocardial infarction. </li></li></ul><li><ul><li>Inferior wall MI –ST segment elevation of > 1mm in inferior leads with reciprocal ST segement depression in anterior leads.
CK, CK MB --- CK rises within 4-8 hrs and returns to normal by 48-72 hrs.
A ratio (relative index) CKMB mass :CK actvity > 2.5 suggests but not diagnostic of acute MI rather than the skeletal source of CKMB elevation.</li></li></ul><li>Treatment<br /> golden period is 1 hr ….<br />Door to needle time -30 min,door to balloon time is <90 min<br />< 6 hrs <br /><ul><li>PCI = thrombolysis</li></ul> <6 hrs with hypotension,cardiogenic shock<br /><ul><li>PCI</li></ul> < 6 hrs with hypotension ,no PCI center <br /><ul><li>Give IV fluids --
Then thrombolysis with cardiac monitoring.</li></ul> In presenceofbradycardia<br /><ul><li>Give atropine</li></ul> In presence of CHB<br /><ul><li>Temporary pacemaker </li></li></ul><li>Management<br /><ul><li>1.Aspirin
Block the formation of thromboxane A2 in the platelets by COX inhibition.
Clopidogrel to be added to apsirin to all patients with STEMI regardless of whether or not perfusion is given and continued for atleast 14 days,and generally for 1 year.</li></li></ul><li>Reperfusion therapy<br /><ul><li>Limitation of the infarct size
The patient at discharge should be sent for angiography in case of absence of PCI not done < 6 hrs….but thrombolysis given, for the evaluation of the vessel blockage …and extent of vessel disease,. </li></li></ul><li>Thrombolysis/fibrinolysis<br />To maintain the patency of the coronary artery.<br />Fibrinolytics agents used :<br />Tissue plasminogen activator<br />Tenectplase<br />Reteplase<br />Alteplase ---GUSTO trial<br />tpA---- 15 mg bolus followed by 50 mg intravenously IV over the first 30 min followed by 30 mg over the next 60 min.<br />Tenectplase – IV bolus of 0.53 mg/kg over 10 sec<br />Reteplase – 10 MU bolus given over 2 -3 min followed by 2nd 10 MU units 30 min later.<br />Streptokinase--- 15 MU given over 1 hr –hypotension. <br />
Relative --- pregnancy,hemorrhagic diabetic retinopathy,active peptic ulcer disease,severe HTN ,allergic reactions .<5 days- 2yrs.,trauma within 2-4 weeks,major surgery within 3 weeks,traumatic CPR ,current use of anticoagulants INR >2-3.</li></li></ul><li>Antithrombotic agents<br />Goal is to maintain the patency of the infarct related artery in conjunction with reperfusion related strategies.<br />UFH --- 60 U/kg followed by infusion of 12 U/kg/hr<br />The APTT should be 1.5 – 2 times the control value.<br />LMWH – enoxaparin 30 mg IV bolus –1mg/kg every 12 hrs---ASSENT 3 trial. <br />Decreased the death at day 30 compared to UFH –EXTRACT trial <br />OASIS 6 trial – fondaparinux given at dose of 2.5 mg /day reduced death and reinfarction .no benefit in patients udergoing PCI –catheter thrombosis..<br />Use antacids and an H2 blocker as prophylactically<br />
Asessment of reperfusion<br /><ul><li>Early cessation of pain
The resolution of the ST segment elevation at 90 min.
50% resolution of ST elevation can occur even without reperfusion –still a strong predictor of better outcome.
Reinfarction – recurrence of pain and ST segment elevation –angio and PCI. </li></li></ul><li>General measures<br /><ul><li>Activity :
Stress testing –see for ST segment depression during submximal exercise –positive send him for angiography---revascualrization.</li></li></ul><li>TIMI grading <br /><ul><li>Thrombolysis in myocardial infarction
Grade 0 –complete occlusion of the infarct related artery.
Grade 1 – some penetration of the contrast material beyond the point of obstruction,but without the perfusion of the distal coronary bed.
Grade 2 – perfusion of the entire infarct vessel into the distal bed but with flow that is delayed compared with that of the normal artery.
Grade 3 – full perfusion of the infarct vessel with normal flow. </li></li></ul><li>GRACE score<br />Global Registry of Acute Coronary Events (GRACE) Hospital Discharge Risk Score Accurately Predicts Long-Term Mortality Post Acute Coronary Syndrome<br />
Acute Inferolateral MI with 2:1 AVblock<br />
Acute inferior wall MI and complete AV block<br />
Take home message<br />Inferior wall MI presents with nausea and abdominal pain also.<br />Inferior wall in 30-50% cases is assosciated with RV MI.<br />Take right sided V4R in all the patients with IWMI.<br />Presence of RVMI increases the mortality of the patients.<br />IV fluids and inotropes,pacing play a equally contributing role in the management of patients on presentation.<br />Recurrence of IWMI at the same site is more than in the anterior wall MI.<br />Triad of raised JVP ,hypotension and clear lungs think of RVMI.<br />PWMI in case of R wave in V1 with upright T wave and R/S ratio >1 V1 and V2..take leads V7-9.<br />