Since the introduction of reperfusion in the treatment of acute myocardial infarction (AMI), rates of ventricular septal rupture (VSR) and associated mortality have decreased, but it is not known if incidence and mortality have continued to decrease. We describe trends in incidence and mortality rates of patients with postinfarction VSR during the previous 2 decades and identify risk factors that predict the development and mortality of this rare but catastrophic complication. We analyzed occurrence and mortality rates in patients with first AMI with (n = 408) and without VSR (n = 148,473) who were hospitalized from 1990 to 2007 using the New Jersey Myocardial Infarction Data Acquisition System (MIDAS) database. The annual rate of VSR in AMI was 0.25% to 0.31%. Compared to patients with AMI without VSR, patients with VSR were older, more likely to be women, had increased rate of chronic renal disease, congestive heart failure, and cardiogenic shock, and were less likely to be hypertensive or diabetic (all p values <0.0001). During the 18-year study period, we found no change in hospital and 1-year mortalities, which were 41% and 60% in 1990 to 1992 and 44% and 56% in 2005 to 2007, respectively. The survival benefit associated with VSR surgical repair was seen only in hospital (hazard ratio 0.66, 95% confidence interval 0.45 to 0.95) but not at 30 days or 1 year. In conclusion, despite improvement in medical treatment and revascularization techniques, the rate of VSR complicating AMI has not changed during the previous 2 decades, and the mortality associated with VSR has remained high and relatively constant.
Before reperfusion therapy was introduced, the incidence of ventricular septal rupture (VSR) complicating acute myocardial infarction (AMI) was 1% to 3% and was associated with extremely poor outcome, with in-hospital mortality rates of about 45% for surgically treated patients and 90% for those treated medically. With the advent of thrombolytic therapy there was a significant decrease in incidence of VSR to approximately 0.2% to 0.4%. Similarly, when using primary percutaneous coronary intervention as the reperfusion technique, the reported incidence of VSR was 0.2% to 0.5%. Although this decrease is encouraging, the mortality rate of this complication compared to AMI without VSR has remained high. Several studies have attempted to identify predictors of survival to optimize treatment decisions for VSR; however, their conclusions were limited by small numbers of patients. This report describes trends in incidence rates and mortality of patients with VSR complicating AMI from 1990 to 2007 and identifies risk factors that predict development and mortality of this rare but catastrophic complication.
Methods
Data for this study were obtained from the Myocardial Infarction Data Acquisition System (MIDAS) database. This administrative database contains discharge records of all patients admitted to nonfederal acute care hospitals in New Jersey with a cardiovascular disease diagnosis. This database was previously audited using a random sample of charts to verify the accuracy of the information. The study was approved by the State of New Jersey Department of Health and Senior Services and Robert Wood Johnson Medical School institutional review boards.
The study cohort consists of 148,881 adult patients (≥35 years of age) admitted for the first time to all nonfederal New Jersey hospitals with a diagnosis of acute ST-segment elevation myocardial infarction (excluding non ST-segment elevation infarctions; International Classification of Diseases [ICD] code 410.7) from 1990 to 2007. Four hundred eight patients with VSR complicating AMI were identified by the diagnosis code for acquired VSR (ICD code 429.71, n = 338) or a procedure code indicating VSR surgical repair (ICD codes 35.53, 35.62, or 35.72, n = 70) within 28 days after index AMI hospitalization.
Primary end points were mortality in hospital, at 30 days, and at 1 year. Covariates included patient demographics and co-morbidities; ST-segment elevation infarction site; anterior, inferior/lateral/posterior, other or unspecified; length of hospital stay; development of cardiogenic shock; and procedures. Risk adjustment included the following factors: presence or absence of diabetes, hypertension, chronic renal disease, congestive heart failure, cardiogenic shock, and length of hospital stay. Procedures included cardiac catheterization (ICD codes 37.21 to 37.23), angioplasty (ICD codes 36.01, 36.02, 36.05, and 00.66), percutaneous coronary intervention (ICD codes 36.00 to 36.09), VSR surgical repair (ICD codes 35.53, 35.62, and 35.72), and coronary artery bypass graft surgery (ICD codes 36.10 to 36.19, 36.2).
We compared demographic, clinical, and cardiac procedures, length of stay, and mortality data for patients with AMI complicated by VSR to those without VSR. Incidence and mortality rates were plotted in 3-year periods. We used Pearson chi-square test for categorical variables and Student’s t test for continuous variables to compare clinical and demographic characteristics. We used the Cochran-Armitage trend test to examine time trends for VSR rates and procedural rates. Kaplan-Meier survival curves (product–limit method) were constructed for patients with VSR with and without surgical repair. We used multivariate logistic regression to analyze potential risk factors and Cox proportional hazards method for survival analyses. All statistical analyses were performed using SAS 9.1 (SAS Institute, Cary, North Carolina).
Results
From 1990 to 2007, 148,881 patients were hospitalized in New Jersey with ST-segment elevation AMI for the first time, and 408 of these developed VSR. Compared to patients without VSR ( Table 1 ), these patients were older, more likely to be women, and to have higher rate of chronic kidney disease, heart failure, cardiogenic shock, and cardiac arrest. Diagnoses of hypertension and diabetes mellitus were less common in patients with AMI and VSR. Anterior wall MI was more frequently observed in patients with VSR than in patients without, but that was not true for patients with inferior/lateral wall AMI. Of patients with VSR, anterior wall AMI was seen in 43% of patients, whereas inferior/lateral location was seen in 49% and other/unspecified in 8.6%. The probability of having VSR in patients with anterior AMI was not different (0.32%) from those with inferior/lateral AMI (0.21%, p = 0.10).
| Variable | VSR | p Value | |
|---|---|---|---|
| Yes (n = 408) | No (n = 148,473) | ||
| Age (years) | 71 ± 10 | 67 ± 14 | <0.0001 |
| Women | 210 (52%) | 57,125 (39%) | <0.0001 |
| White | 315 (77%) | 116,199 (78%) | 0.26 |
| Hypertension | 116 (28%) | 67,698 (46%) | <0.0001 |
| Diabetes mellitus | 73 (18%) | 35,563 (24%) | 0.004 |
| Chronic kidney disease | 110 (27%) | 8,759 (5.9%) | <0.0001 |
| Heart failure | 185 (45%) | 39,632 (27%) | <0.0001 |
| Atrial fibrillation | 80 (20%) | 19,059 (13%) | <0.0001 |
| Cardiogenic shock | 160 (39%) | 8,771 (5.9%) | <0.0001 |
| Cardiac arrest | 25 (6.1%) | 6,124 (4.1%) | 0.04 |
| Length of stay (days) | 12 ± 18 | 7 ± 9 | <0.0001 |
| Location of infarction | |||
| Anterior wall | 175 (43%) | 54,464 (37%) | 0.009 |
| Inferior/lateral wall | 198 (49%) | 73,002 (49%) | 0.80 |
| Other/unspecified | 35 (8.6%) | 21,007 (14%) | 0.001 |
| Cardiac procedures | |||
| Diagnostic catheterization | 241 (59%) | 53,531 (36%) | <0.0001 |
| Percutaneous intervention | 50 (12%) | 27,445 (19%) | 0.001 |
| Coronary artery bypass | 133 (33%) | 7,793 (5.3%) | <0.0001 |
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