Role of genotyping in risk factor assessment for sudden death in hypertrophic cardiomyopathy

Myocardial tissue characterization using magnetic resonance noncontrast t1 mapping in hypertrophic and dilated cardiomyopathy

BACKGROUND

Noncontrast magnetic resonance T1 mapping reflects a composite of both intra- and extracellular signal. We hypothesized that noncontrast T1 mapping can characterize the myocardium beyond that achieved by the well-established late gadolinium enhancement (LGE) technique (which detects focal fibrosis) in both hypertrophic (HCM) and dilated (DCM) cardiomyopathy, by detecting both diffuse and focal fibrosis.

METHODS AND RESULTS

Subjects underwent Cardiovascular Magnetic Resonance imaging at 3T (28 HCM, 18 DCM, and 12 normals). Matching short-axis slices were acquired for cine, T1 mapping, and LGE imaging (0.1 mmol/kg). Circumferential strain was measured in the midventricular slice, and (31)P magnetic resonance spectroscopy was acquired for the septum of the midventricular slice. Mean T1 relaxation time was increased in HCM and DCM (HCM 1209±28 ms, DCM 1225±42 ms, normal 1178±13 ms, P<0.05). There was a weak correlation between mean T1 and LGE (r=0.32, P<0.001). T1 values were higher in segments with LGE than in those without (HCM with LGE 1228±41 ms versus no LGE 1192±79 ms, P<0.01; DCM with LGE 1254±73 ms versus no LGE 1217±52 ms, P<0.01). However, in both HCM and DCM, even in segments unaffected by LGE, T1 values were significantly higher than normal (P<0.01). T1 values correlated with disease severity, being increased as wall thickness increased in HCM; conversely, in DCM, T1 values were highest in the thinnest myocardial segments. T1 values also correlated significantly with circumferential strain (r=0.42, P<0.01). Interestingly, this correlation remained statistically significant even for the slices without LGE (r=0.56, P=0.04). Finally, there was also a statistically significant negative correlation between T1 values and phosphocreatine/adenosine triphosphate ratios (r=-0.59, P<0.0001).

CONCLUSIONS

In HCM and DCM, noncontrast T1 mapping detects underlying disease processes beyond those assessed by LGE in relatively low-risk individuals.

The progression of left ventricular systolic and diastolic dysfunctions in hypertrophic cardiomyopathy: clinical and prognostic significance

OBJECTIVES

The significance of the progression of systolic and diastolic dysfunctions in hypertrophic cardiomyopathy (HCM) is still an open issue. We sought to evaluate the clinical and prognostic implications of the progression of left ventricular systolic and diastolic dysfunction in HCM.

METHODS

One hundred one HCM patients were studied by echo-Doppler at baseline and during follow-up.

RESULTS

During a follow-up of 109 + or - 67 months, 28% of patients showed a progression to left ventricular diastolic dysfunction, defined as restrictive filling pattern (RFP), and 16% to left ventricular systolic dysfunction (left ventricular ejection fraction <50%). The 10-year heart transplant-free survival rate was 45% in patients with RFP at follow-up vs. 82% in the patients without RFP (P < 0.001), and 52% in patients with left ventricular systolic dysfunction at follow-up vs. 75% in the patients with left ventricular ejection fraction of at least 50% (P = 0.001). Baseline predictors of death/transplantation were New York Heart Association class III-IV, indexed left atrial diameter, and RFP. When RFP and left ventricular systolic dysfunction were added at follow-up, both emerged as prognostic predictors (RFP: hazard ratio 8.92, 95% confidence interval 2.5-31.86; systolic dysfunction: hazard ratio 25.35, 95% confidence interval 3.57-179.88) with a significant increase of area under the receiver-operating characteristic curves (0.81 vs. 0.70, P = 0.03) with respect to the baseline model.

CONCLUSION

Left ventricular diastolic and/or systolic dysfunction at follow-up are relatively frequent in HCM and are associated with a poor prognosis.

Noncardiac surgery and the risk of death and other cardiovascular events in patients with hypertrophic cardiomyopathy

BACKGROUND

There is a paucity of reports evaluating the perioperative risk of noncardiac surgery in patients with hypertrophic cardiomyopathy (HCM).

HYPOTHESIS

The study was undertaken to evaluate the incidence of acute myocardial infarction (MI) and all-cause inhospital mortality following noncardiac surgery in patients with HCM.

METHODS

We searched the National Hospital Discharge Survey database for patients with a diagnosis of HCM who had undergone noncardiac surgery. Cases were matched by age, gender, and year of surgery. Death or acute MI were used as endpoints for analysis.

RESULTS

From 1996 to 2002, 227 patients with HCM were matched with 554 controls (representing national estimates of 25,874 HCM and 50,326 controls patients). Patients with HCM were more likely than controls to have a history of atrial fibrillation (22.7 vs. 10.6%, p < 0.001) and of congestive heart failure (CHF) (24.2 vs. 14.1%, p < 0.001). The in-hospital incidence of death or MI was higher in patients with HCM than in controls (6.7 vs. 2.5%, p < 0.001 for death and 2.2 vs. 0.3%, p < 0.001 for MI). After correcting for age, gender, race, presence of hypertension, diabetes mellitus, history of coronary artery-disease, history of CHF, atrial fibrillation, and ventricular arrhythmias in a multivariate binary logistic regression model, the presence of HCM increased the odds of death by 61% (odds ratio [OR] = 1.61, 95% confidence interval [CI] 1.46-1.77, p < 0.001), and almost tripled the odds of the combined endpoint of death or MI (OR = 2.82, 95% CI 2.59-3.07, p < 0.001).

CONCLUSION

The presence of HCM significantly increases the risk of death and MI associated with noncardiac surgery. Patients with HCM undergoing elective procedures may require more careful preoperative assessment and perioperative monitoring. The impact of the severity of HCM on outcomes of noncardiac surgery needs further study.