November 17, 2011 (Lakeland, Florida) — As the number of traditional CHD risk factors increased, the likelihood of in-hospital death after a first MI decreased, in a large, observational study [1]. This surprising, inverse relationship does not mean that clinicians should cease treating modifiable risk factors, the authors caution. Almost all patients (85.6%) had at least one of the five risk factors--hypertension, smoking, dyslipidemia, diabetes, or an immediate relative diagnosed with CHD before age 60.
"The one thing I would like to emphasize . . . is that we are not in any way, shape, or form saying that having risk factors is a good thing," lead author Dr John G Canto (Watson Clinic, Lakeland, FL) told heartwire . "People who have CHD risk factors are more likely to get treatment, and it is likely the treatment of these risk factors really does make a difference when the patient subsequently has a heart attack," he suggested.
"The clinical implication is that treating CHD factors makes a tremendous difference in reducing CHD mortality, and conversely, the absence of CHD risk factors does not necessarily portend a good prognosis after heart attack," he added.
The study, based on data from over 500 000 patients listed in the 1994–2006 National Registry of Myocardial Infarction (NRMI), is published in the November 16, 2011 issue of the Journal of the American Medical Association.
Sicker, Younger Patients?
Little is known about the relationship between having any number of major traditional CHD risk factors and dying in the hospital from any cause following an initial MI, the authors write. To investigate this, they analyzed data from the NRMI database.
Hypertension was the most common risk factor (52.3% of patients), followed by smoking (31.3%), dyslipidemia (28.0%), family history of CHD (28.0%), and diabetes (22.4%).
Only 14.4% of the patients had no CHD risk factors, prompting Canto to say: "I think that from this point forward we can lay to rest the myth that patients with MI and no risk factors are relatively common."
Patients with "no" risk factors were older and had more cardiogenic shock, higher TIMI risk score, and higher Killip class when they had their first MI. On average, patients with five risk factors were 56.7 years old, whereas patients with no risk factors were 71.5 years old when they presented.
In each risk category, about 41% of the patients were women. Black patients were more likely to have more risk factors.
Patients with few or no risk factors were less likely to receive evidence-based medications or invasive cardiac procedures within the initial 24 hours in the hospital.
The total number of in-hospital, all-cause deaths was 50 788. Hospital mortality increased consistently as the number of risk factors declined.
Mortality vs Number of CHD Risk Factors
Compared with patients who had all five risk factors, patients with no risk factors were 54% more likely to have a fatal first MI (odds ratio 1.54; 95% CI 1.23–1.94), after adjustment for age, weight, sex, race/ethnicity, payer status, systolic blood pressure, prehospital delay, Killip class, hospital characteristics, region, type of MI, and calendar year.
Canto suggested that among multiple potential reasons for the counterintuitive study findings, three hypotheses are most compelling. "First, patients who have risk factors may be more likely to be on aspirin, statins, and antihypertensives--all known to improve CHD outcomes," he said. "Second, they are more likely to have closer medical follow-up to manage their risk factors, which is associated with better outcomes. Finally, I suspect that the biology of disease may be different in older patients without CHD risk factors. . . . Eventually age becomes a risk factor. Some data show that older patients without a disease state are less likely to have collateral circulation in the heart."
Intriguing Findings, More Study Needed
Asked to comment on the study, Dr Ramachandran S Vasan (Framingham Heart Study, MA) said, "I am intrigued by the observed association, as it is the opposite of what one would predict based on our knowledge of the biology and epidemiology of CVD risk factors.
"Additional studies are warranted to confirm these findings and to evaluate associations with long-term outcomes in MI patients," he said.
"Until we are able to better understand the possible reasons for the 'observed association,' one would be very cautious about trying to make inferences for clinical practice. The authors do discuss several potential reasons for the observed association, and they seem reasonable possibilities," Vasan concluded.
The NRMI was supported by Genentech. Canto and Vasan have no relevant disclosures. Disclosures for the coauthors are listed in the paper.
"The one thing I would like to emphasize . . . is that we are not in any way, shape, or form saying that having risk factors is a good thing," lead author Dr John G Canto (Watson Clinic, Lakeland, FL) told heartwire . "People who have CHD risk factors are more likely to get treatment, and it is likely the treatment of these risk factors really does make a difference when the patient subsequently has a heart attack," he suggested.
"The clinical implication is that treating CHD factors makes a tremendous difference in reducing CHD mortality, and conversely, the absence of CHD risk factors does not necessarily portend a good prognosis after heart attack," he added.
The study, based on data from over 500 000 patients listed in the 1994–2006 National Registry of Myocardial Infarction (NRMI), is published in the November 16, 2011 issue of the Journal of the American Medical Association.
Sicker, Younger Patients?
Little is known about the relationship between having any number of major traditional CHD risk factors and dying in the hospital from any cause following an initial MI, the authors write. To investigate this, they analyzed data from the NRMI database.
Hypertension was the most common risk factor (52.3% of patients), followed by smoking (31.3%), dyslipidemia (28.0%), family history of CHD (28.0%), and diabetes (22.4%).
Only 14.4% of the patients had no CHD risk factors, prompting Canto to say: "I think that from this point forward we can lay to rest the myth that patients with MI and no risk factors are relatively common."
Patients with "no" risk factors were older and had more cardiogenic shock, higher TIMI risk score, and higher Killip class when they had their first MI. On average, patients with five risk factors were 56.7 years old, whereas patients with no risk factors were 71.5 years old when they presented.
In each risk category, about 41% of the patients were women. Black patients were more likely to have more risk factors.
Patients with few or no risk factors were less likely to receive evidence-based medications or invasive cardiac procedures within the initial 24 hours in the hospital.
The total number of in-hospital, all-cause deaths was 50 788. Hospital mortality increased consistently as the number of risk factors declined.
Mortality vs Number of CHD Risk Factors
| Risk factors, n | In-hospital mortality, % of patients |
| 0 | 14.9 |
| 1 | 10.9 |
| 2 | 7.9 |
| 3 | 5.3 |
| 4 | 4.2 |
| 5 | 3.6 |
Canto suggested that among multiple potential reasons for the counterintuitive study findings, three hypotheses are most compelling. "First, patients who have risk factors may be more likely to be on aspirin, statins, and antihypertensives--all known to improve CHD outcomes," he said. "Second, they are more likely to have closer medical follow-up to manage their risk factors, which is associated with better outcomes. Finally, I suspect that the biology of disease may be different in older patients without CHD risk factors. . . . Eventually age becomes a risk factor. Some data show that older patients without a disease state are less likely to have collateral circulation in the heart."
Intriguing Findings, More Study Needed
Asked to comment on the study, Dr Ramachandran S Vasan (Framingham Heart Study, MA) said, "I am intrigued by the observed association, as it is the opposite of what one would predict based on our knowledge of the biology and epidemiology of CVD risk factors.
"Additional studies are warranted to confirm these findings and to evaluate associations with long-term outcomes in MI patients," he said.
"Until we are able to better understand the possible reasons for the 'observed association,' one would be very cautious about trying to make inferences for clinical practice. The authors do discuss several potential reasons for the observed association, and they seem reasonable possibilities," Vasan concluded.
The NRMI was supported by Genentech. Canto and Vasan have no relevant disclosures. Disclosures for the coauthors are listed in the paper.
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