Congestive Heart Failure

ICD Referral Guidelines

Heart Failure Evidence

Every Day is Heart Failure Awareness Day. As you are aware, Heart Failure (HF) is the only major cardiovascular disorder that is increasing in incidence and prevalence. This is due in part to the aging population but as well to the increasing prevalence and poor control of CHF precursors such as hypertension, diabetes, hyperlipidemia, smoking and LVH. Approximately 1.5 - 2 % of the population have Heart Failure and the prevalence increases to 6 -10 % of the population > 65 years old. Heart Failure is the leading cause of hospitalization in the elderly and a frequent cause  of death. Asymptomatic LV (left ventricular) dysfunction is even more common and is often unrecognized.

Clinical trials have shown average annual mortality rates in stable Heart Failure patients of around 10% with a 50% five-year survival rate. Intervention with ACE inhibitors, such as the SOLVD treatment arm [1] (clinical CHF and LVEF < 35 %; enalapril 2.5-20 mg./day) showed a 16% relative reduction in mortality over a 41 month period. In the SOLVD prevention arm [2] (patients with similar EF’s but minimal symptoms) ACE inhibitors showed a significant reduction in the combined end-point of new heart failure and cardiovascular mortality (relative risk reduction 20%). In the RALES Trial [3], spironolactone, an aldosterone receptor blocker, when added to ACE-inhibitor/diuretic/+/- digoxin in stable Class III-IV CHF/LVEF < 35%, has shown an 11% absolute (ARR) and 30% relative risk reduction (RRR) for death in HF patients. The addition of beta-blocker therapy to standard triple therapy for HF (digoxin, diuretic and ACE inhibitor) such as in the U.S. Carvedilol Trials [4] (LVEF < 35%; carvedilol 12.5-100mg/day) have shown a further 65% RRR in CV mortality (7.8% to 3.2 % ARR) in patients with NYHA class II-IV symptomatic HF. Carvedilol has also been shown to produce a dose related increase in LVEF which averaged 8% and to lead to a 27% relative risk reduction in cardiovascular hospitalizations. Similar benefits were obtained in other trials of beta-blockers in Heart Failure (MERIT [5] -metoprolol and CIBIS II [6] - bisoprolol).

The recent ICES Atlas of Cardiovascular Health and Services in Ontario has demonstrated an astounding 33% annual mortality for patients hospitalized for HF over the years 1994-1997. This discrepancy in outcomes between clinical trials and clinical reality may in part be attributable to patient selection in the clinical trials, but nevertheless there is a huge care gap that must be overcome. Components of that care gap include:

  • Failure to recognize and treat HF early enough
  • Lack of continuity in follow-up
  • Lack of educational resources for patients re:
  • Lifestyle modification
  • Dietary measures (salt and water restriction) to control HF
  • Risk factor modification
  • Exercise and physical activity
  • Under use and failure to optimize the dose of ACE inhibitors
  • Under use and failure to optimize the dose of Beta-blockers

[1] NEJM 1991; 325:293-302.
[2] NEJM 1992; 327:685-691.
[3] NEJM 1999; 341: 709-717.
[4] NEJM 1996; 334:1349-1355.
[5] Lancet 1999; 353: 2001-2007.
[6] Lancet 1999; 353: 9-13

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  Version 2.0, July 2004
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