Mitral insufficiency as a complication of acute myocardial infarction and left ventricular remodeling

Mitral Regurgitation Following Acute Myocardial Infarction Treated by Percutaneous Coronary Intervention-Prevalence, Risk factors, and Predictors of Outcome

Mitral regurgitation (MR) following acute myocardial infarction (AMI) worsens prognosis and reports of prevalence vary significantly. The objective was to determine prevalence, risk factors, and outcomes related to MR following AMI. We identified 1000 consecutive patients admitted with AMI in 2016/17 treated by percutaneous coronary intervention with pre-discharge transthoracic echocardiography. MR was observed in 294 of 1000 (29%), graded as mild (n = 224 [76%]), moderate (n = 61 [21%]) and severe (n = 9 [3%]). Compared with patients without MR, patients with MR were older (70 ± 12 vs 63 ± 13 years; p <0.001), with worse left ventricular ejection fraction (LVEF) (52 ± 15% vs 55 ± 11%; p <0.001) and creatinine clearance (69 ± 33 ml/min vs 90 ± 39 ml/min; p <0.001). They also had higher rates of hypertension (64% vs 55%; p = 0.012), heart failure (3.4% vs 1.1%; p = 0.014), previous MI (28% vs 20%; p = 0.005) and severe flow-limitation in the circumflex (50% vs 33%; p <0.001) or right coronary artery (51% vs 42%; p = 0.014). Prevalence and severity of MR were unaffected by AMI subtype. Revascularization later than 72 hours from symptom-onset was associated with increased likelihood of MR (33% vs 25%; p = 0.036) in patients with non-ST elevation myocardial infarction (NSTEMI). After a mean of 3.2 years, 56 of 288 (19%) patients with untreated MR died. Age and LVEF independently predicted mortality. The presence of even mild MR was associated with increased mortality (p = 0.029), despite accounting for confounders. In conclusion, MR is observed in over one-quarter of patients after AMI and associated with lower survival, even when mild. Prevalence and severity are independent of MI subtype, but MR was more common with delayed revascularization following NSTEMI.

Functional mitral regurgitation after a first non-ST-segment elevation acute coronary syndrome: contribution to congestive heart failure

AIMS

Functional mitral regurgitation (MR) is a frequent complication after the acute phase of a myocardial infarction and plays an important role in the development of congestive heart failure (CHF) after a Q-wave myocardial infarction. Nevertheless, until now, the relevance of functional MR after a non-ST-segment elevation acute coronary syndrome (NSTSEACS) has been poorly addressed. Our aim was to assess the relationship between the presence or absence and the severity of functional MR after a first NSTSEACS and the development of CHF.

METHODS AND RESULTS

Two hundred and seventy-nine patients discharged from hospital in NYHA functional classes I and II (71.7% men; mean age 66.3 +/- 13.2 years) after a first NSTSEACS were studied. Every patient underwent an echocardiographic study during the first week after the index NSTSEACS and were clinically followed-up. MR was detected in 40.1% patients. Patients were followed-up for a median time of 418 days (inter-quartile range: 295-561). Six patients (3.6%) in the group without MR and 15 patients (13.4%) in the group with MR required hospitalization due to CHF during follow-up. Only MR was found as an independent predictor of CHF development (HR = 1.8; 95% CI = 1.1-3.1; P = 0.02) and CHF development or cardiac death (HR = 2.1; 95% CI = 1.3-3.3; P = 0.01) in the long-term follow-up multivariable Cox regression analysis.

CONCLUSION

There is an increased risk for subsequent CHF in patients with MR after a first NSTSEACS. The risk of CHF is closely related to the MR presence and severity. Thus, the detection of MR by means of Doppler echocardiography after a first episode of NSTSEACS is crucial.

Mitral regurgitation after myocardial infarction: a review

Mitral regurgitation after myocardial infarction is the result of multifactorial processes involving local and global left ventricular remodeling. The prevalence of mitral regurgitation varies from 11% to 59%. Published studies differ greatly in design, inclusion criteria, duration of follow-up, and technique of mitral regurgitation assessment. However, they consistently indicate that mitral regurgitation after myocardial infarction carries an adverse prognosis with increased risk of death and heart failure independently of previously known indicators of risk after myocardial infarction. Mitral regurgitation is often clinically silent; therefore, it should be systematically evaluated by echocardiography. Standard color Doppler imaging is a highly sensitive method to detect even mild degrees of ischemic mitral regurgitation. One unique advantage of echocardiography is that it accurately quantifies the severity of mitral regurgitation by measuring the effective regurgitant orifice area and the regurgitant volume using Doppler methodology. Therefore, the evaluation should include precise quantification of the degree of mitral regurgitation to best appraise the ensuing risk. Current medical options rely chiefly on angiotensin converting enzyme-inhibitors and beta-blocker therapy, and surgical approaches offer future promise. Both categories of therapeutic approaches should be evaluated by randomized controlled trials.

Mitral regurgitation following acute myocardial infarction

Mitral valve regurgitation (MR) is a frequent Doppler echocardiographic finding in patients after acute myocardial infarction (AMI) and an independent predictor of long-term cardiovascular mortality. Reported risk factors include advanced age, prior myocardial infarction, infarct extension, and recurrent ischemia. During the early phase of AMI, transient ischemic MR is common and rarely causes hemodynamic compromise. However, when several chordae tendineae or a papillary muscle ruptures, acute left atrial and ventricular volume overload ensues, leading to abrupt hemodynamic deterioration with cardiogenic shock. Auscultation may be unrevealing due to decreased turbulence. Hence, the importance of a high index of suspicion for acute MR in any patient with acute pulmonary edema in the setting of AMI, especially if left ventricular systolic function is well preserved. Later, ventricular remodeling may lead to MR through annular dilatation or papillary muscle migration with malcoaptation of the leaflets. The widespread availability, ease of use and non-invasive nature of Doppler echocardiography have made it the standard diagnostic tool for detecting MR. Mechanical reperfusion of the infarct-related artery seems to be superior to fibrinolysis in decreasing its incidence acutely and in the long run. Nevertheless, when acute severe MR occurs, unless rapidly diagnosed and treated, this dreaded complication is associated with high morbidity and mortality. Prompt surgical intervention after hemodynamic stabilization is essential to ensure a good short-term and long-term prognosis. This review discusses the incidence, long-term prognosis, associated risk factors, complex pathophysiology, time of occurrence, clinical manifestations, diagnosis, and management of patients with MR after AMI.

A survival case of acute mitral regurgitation and cardiogenic shock caused by subtotal occlusion of the first diagonal branch

An 80-year-old woman was admitted with cardiogenic shock; she arrived in a deep coma with systolic blood pressure of 44 mmHg. An electrocardiogram showed ST elevation in I, aVL, V5 and V6, suggesting myocardial infarction in the lateral area of the left ventricle. A chest roentgenogram showed right pulmonary edema without cardiomegaly. Transthoracic and transesophageal echocardiograms revealed severe mitral regurgitation and a flailing anterior mitral valve leaflet, suggesting a ruptured papillary muscle. The patient was initially treated with high-dose dopamine, dobutamine and norepinephrine. Intraaortic balloon pumping was initiated after the patient's condition stabilized. She underwent emergency mitral valve replacement with a prosthetic valve. Complete rupture of the anterior papillary muscle was confirmed. Histological examination revealed necrosis of the anterior papillary muscle with inflammatory changes. She recovered uneventfully. Postoperative coronary angiography demonstrated subtotal occlusion of the first diagonal branch, and left ventriculography demonstrated akinesis of the lateral segment. This was a rare case in which subtotal occlusion of the first diagonal branch caused rupture of an anterior papillary muscle leading to severe mitral regurgitation.